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Old 07-16-2019, 11:41 AM   #1
MisterBLC
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Default Coolant Temp Threads Messed up - Repair options in PDX

So frustrated! Went to fix a weeping coolant temp sensor on my wife's '94 940T. The head was previously rebuilt and I had the shop install new sensors (I think the head I used originally had the early style 1-wire sensor...converted to the later 2-wire sensor). However, apparently the shop cross threaded the sensor so when I went to tighten it, the sensor just popped and spun easily. Pulling it out, the sensor was clearly cross threaded and new sensor when spun in go in cock-eyed and won't tighten

Sensor: https://www.ipdusa.com/products/7209...ge-swf-1362645

Looking for repair options. I think my best bet is some sort of helicoil solution (threads are M16x1.5)...but repair kits are expensive. Anyone in the PDX area have one I can borrow? Any other alternative solutions I am not thinking of?

Thanks!
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Old 07-16-2019, 12:16 PM   #2
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I wonder whether wrapping teflon tape around the threads would solve the problem?
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Old 07-16-2019, 12:36 PM   #3
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Are you sure the sender is in the correct hole? It should be in #2.



The temp sender has 5/8"-18 threads but they don't do the sealing. The beveled part below the threads is what seals the sender.



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Old 07-16-2019, 02:29 PM   #4
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Yes, right spot just above the knock sensor.

The threads are straight threads...tape/goop isn't going to work as the threads aren't the sealing point...the tapered seat should be what seals the sensor.
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Old 07-22-2019, 07:06 PM   #5
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Ok update...so I didn't get a good pciture, but apparently the old style 1-wire sensor was not as deep as the new style 2-wire sensor. Both are the same threads, so when the machine shop installed the new 2-wire sensor in the head, it only engaged the outer 2 threads or so, which were the ones damaged. I bought an old-style 1-wire sensors, cleaned up the threads remaining in the head with a tap, and was able to install the 1-wire sensor in the head successfully! Now I just need to modify the gauge wiring so that the 1-wire sensor causes the gauge to read correctly...currently it reads hot. Does anyone know the specs on these two sensors to help me fix up the reading?
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Old 07-22-2019, 08:42 PM   #6
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Does the gauge work at all? Maybe the second wire needs a ground point.
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Old 07-22-2019, 09:14 PM   #7
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Quote:
Originally Posted by MisterBLC View Post
I bought an old-style 1-wire sensor
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Originally Posted by lummert View Post
Does the gauge work at all? Maybe the second wire needs a ground point.
I'd like to know which "old-style 1-wire sensor" he stuck in there. Probably for a 240, which used a 1-wire right to the end of its pitiful life, using the head as a ground. My diagrams say 7/9's all had 2 wires directly from the gauge in a long loop, with the sensor inline, no separate ground required.

240



7/9

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Old 07-22-2019, 11:28 PM   #8
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It looks like the sensor you labelled 240, but its for very early 7's as well...my '85 740 turbo uses it as well. IPD puts this as a 7xx sensor:
https://www.ipdusa.com/products/5907...t-vr850-460191

Gauge does work, but fully warm moves the 940 gauge past center...when the fan kicks in, the gauge is almost to the red. I did need to ground the other wire, otherwise the gauge would move with the blinker!
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Old 07-23-2019, 01:38 PM   #9
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OK another update: the car has a new idle problem that did not exist before this issue with the coolant sensor. Now, as the car heats up and the gauge moves above the midpoint, the idle will slowly drop and drop until the engine almost dies. This behavior seems to go away when the coolant gauge is completely disconnected, although I only tested this once so I'm not 100% this is the case. I did a full smoke test to ensure we didn't introduce any new vaccuum leaks during the removal of the intake manifold to repair the sensor and found nothing. How could the coolant gauge wiring affect idle? So wierd

I also found that turning the headlights on(!) causes the gauge to read much higher...there is some electrical ground loop going on that I don't understand.
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Old 07-23-2019, 01:43 PM   #10
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On latter 7/9s i wanna say the temp gauge is 2-pin and shares a grounding point on the intake manifold that is also shared by the engine coolant temp sensor?

It's rare, but once in a great while I've seen one of the little wire-crimps that holds the multi-ground bundle come loose on 1993-1994 cars if yours is one of those (mom's 1993 244 has that issue & I get to take the engine harness apart/replace it with a non-defective one now that I found all my decent crimper tools).

Kinda sad as 1993-1994 tend to be mostly good years with even some good japanese parts, but with a bit of odd electrical on some.

Having said that, assuming there are no vacuum leaks, the later 2.4 cars seem to idle a bit lower warm and hunt a bit with the 02 sensor switching? But it shouldn't almost die in good repair assuming the throttle position switch/throttle body is clean/adjusted properly.

Good luck.
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Old 07-24-2019, 01:10 PM   #11
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Kjets, are you talking about the crimps on the eyelets for the grounds at the fuel rail? Or are there also crimps elsewhere in the engine wiring harness that go bad?

Throttle switch is definitely correctly adjusted and throttle is reasonably clean...wouldn't hurt to spray a bit in there though as well.
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Old 07-24-2019, 01:38 PM   #12
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More than one ground wire is often joined together into 1 branching out with a crimp under the intake much like the injector wires.


That’s a real outside shot though.
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Old 08-06-2020, 11:00 AM   #13
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Question Seeking Chart for location of sensors for 93 240 DL

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Originally Posted by hiperfauto View Post
Are you sure the sender is in the correct hole? It should be in #2.



The temp sender has 5/8"-18 threads but they don't do the sealing. The beveled part below the threads is what seals the sender.



Could hiperfauto, or anyone, share the chart detailing locations/ details of sensors - but for 1993 Volvo 240 DL (wagon) with A/T? My (new) mechanic and I seem to be at oods about which sensors are needed, and where they go.
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Old 08-06-2020, 11:38 AM   #14
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Question Temp Sensors '93 240 Details & Locations needed

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I'd like to know which "old-style 1-wire sensor" he stuck in there. Probably for a 240, which used a 1-wire right to the end of its pitiful life, using the head as a ground. My diagrams say 7/9's all had 2 wires directly from the gauge in a long loop, with the sensor inline, no separate ground required.

240



7/9

I have struggled with 'overheating' on my 1993 Volvo 240 DL Wagon, A/T since I bought it. A friend and I concluded it's not really overheating. (He persuaded me to purchase IFR gun, and showed me how to use.) Multiple shops/ mechanics confirmed 'it's not overheating.' I did some research that led me to believe it could be temp sensors, or temp compensation board. (BTW long story about how I ended up having to replace that board on '88 240 DL wagon...) Previous shop, when I asked about replacing sensors, basically said 'too much work.' (sigh)
This week I absolutely HAD to put car in shop (NSS & shifter problems, again.) I mentioned 'OH'ing problem' (with belief not really OH'ing) and A/C. We are triple digits in Arizona and I HAVE to get these problems addressed. So - assuming they could get shifter and NSS problems resolved, mechanic was to move on to these other problems.
His conclusion: NOT overheating. His plan: to replace temp sensors. I had included PN 460191 (gauge coolant temp sensor) with parts I took to them. (ALso had new MAF installed, which apparently has made a noticeable difference!) Mechanic swears to me that #460101 is the WRONG part. He keeps insisting it is the SAME part as 'the other sensor' #1364030 (the ECT, engine coolant temp sensor) . He swears BOTH sensors are two 'two prong' and that #460191, being single spade, is absolutely not the right part, even saying if it had been teh right part he would have already put it in.
This turned into discussion that - oh the mfg's changed parts when they could buy from another supplier in bulk, and part designs can be different.' Me: yeah, not so much with Volvos made in Sweden. (Or some my longtime mechanic who loved these cars explained to me....)
I asked him about possibility / probability of temp comp board failing - he firmly believes it's sensors, and absolutely NOT that board. 'We'll put on whatever you want but. ... ' then 'if cover is broken NOT their fault or responsibility, because it's old and brittle.' (This when I mentioned the story of how that board had to be replaced in my '88 after many other parts, including radiator replacement 3 times, had occured - and my understanding it's not more than one hour job - but have to get into dash to R&R. Clearly, if he's this adamant it's sensors (and I agree with him they've probably never been replaced) that it's more probably sensors are the culprit.
HOWEVER we're bogged down on 'which parts.' Of course, I'm in a mail order town. I went to NAPA, who can't get one part, and the other is special order (min. 5 days); they sent me to O'REilly, who confirmed BOTH PN's and gave me pics (also not in stock).; then to Auto Zone, who again confirmed PN's, gave me pics, and can have here overnight (not thrilled with the brands they use ...) Every online resource I checked, TASCA, IPD, RM, eEuro, FCP, ALL stated these 2 PNs.
I actually have #1346030 - just can't find it! (sigh)
So - I went back and explained, again, #460191 IS correct part, and other #1346030 is part I'm not able to locate, and yes, he is correct that I DO need that part as well.
SOOOOO IF he is correct --- possible that previous mechanic put wrong part in wherever #460191 was supposed to be installed - WOULD THAT have created damage? And if so, is this something else that's going to have to be 'fisxed' (and how to fix???) Or just simply put correct sensor in?
IS there yet a THIRD sensor, that is also 2 prong - and this mechanic has just somehow overlooked #460191?
I was at loss because I couldn't explain EXACTLY where sensors are to be installed. I didn't realize #460191 also went into engine, just that it's 'gauge sensor' --- so of course I was looked at like stupid 'duh where do you think that goes???'
And yes, I COULD have let them order part/s ...but my concern is they'll end up with wrong part -- and either just install it because they have it, or car will be down another 2-3 days for them to get 'right part' (which they already have...)
DOES IT MATTER which brand I purchase? #460101 that I have is FAE - given location should I invest in OEM? I'll order another #1364030 - Bosch.
Do I need ANY other parts (like connectors)?
Diagram showing locations of these sensors would be soooo very appreciated.
Sorry this is so lengthy - it's really brief version, considering what I've been thru over this...
BTW I have both Bentley and Haynes manuals - but they're both in car (which is in the shop) ....
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Old 08-06-2020, 11:55 AM   #15
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Quote:
Originally Posted by AlaskanPrincess View Post
Could hiperfauto, or anyone, share the chart detailing locations/ details of sensors - but for 1993 Volvo 240 DL (wagon) with A/T? My (new) mechanic and I seem to be at oods about which sensors are needed, and where they go.
The temp sensors are located underneath intake runners #2 and #3. They can both easily be removed with a 3/4” or 19mm deep socket and an extension. No need to pull the intake manifold, but pulling the intake tube between MAF and intake does help get more space.

Under #2 you will find a single spade sender. This should have a yellow wire with a female spade connector on it. This is for the dash gauge only.

Under #3 you will find a 2 pin sensor that has the same connector as a fuel injector. This is for the ignition computer and fuel computers only. If the car runs well and gets decent fuel mileage, then this sensor is usually OK.



The temp gauge sensors rarely fail, it’s mostly a connection issue or the temp board in the cluster acting up.
The temp gauge wiring goes through the large gray connector between the intake and firewall (near dipstick). This could be causing issues as well. Your starter wire also goes through this connection, might be good to check if you’re having a no start issue.
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Old 08-06-2020, 02:54 PM   #16
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^No connector on the firewall in 1993 on the 240, it's under the passenger footwell cover starting sometime late 1991ish-1992?
Trouble shooting may be more difficult/layout a little different, but no more stupid bullets to have to carefully plug in if their little flanges degrade in heat/oil.

Wiring, compensation or voltage stabilizer or temp gauge in the cluster itself are common enough.

On the 240, the gauge sender should have a yellow wire/single spade and a VDO sender/sensor under the #2 intake runner.
Wouldn't buy anything from napa or aftermarket (all the napa stuff has arrived DOA) and I'd check the gauge sensor back in the passenger foot-well at the yellow wire with an ohm meter to ground compared to ambient and operating temp. There's probably a chart for that, though mostly we check the ECU temp senders to the chart for running problems for either voltage at output or ohms to ground.

I'd want a decent/tropical fan clutch in AZ and clean/decent radiator in any case.

While failure of the temp gauge sender (if it is making a good ground connection (usually yes, tightened against a tapered seat to seal) is not unheard of, it's very very very rare.

If you have good signal back to the connector in the passenger foot well, try another cluster/temp gauge?
Mechanic doesn't want to disturb a bunch of AZ brittle dash plastics? Understandable...
Though the cluster usually comes out willingly.

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Old 08-06-2020, 05:12 PM   #17
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^No connector on the firewall in 1993 on the 240, it's under the passenger footwell cover starting sometime late 1991ish-1992?
Trouble shooting may be more difficult/layout a little different, but no more stupid bullets to have to carefully plug in if their little flanges degrade in heat/oil.

Wiring, compensation or voltage stabilizer or temp gauge in the cluster itself are common enough.

On the 240, the gauge sender should have a yellow wire/single spade and a VDO sender/sensor under the #2 intake runner.
Wouldn't buy anything from napa or aftermarket (all the napa stuff has arrived DOA) and I'd check the gauge sensor back in the passenger foot-well at the yellow wire with an ohm meter to ground compared to ambient and operating temp. There's probably a chart for that, though mostly we check the ECU temp senders to the chart for running problems for either voltage at output or ohms to ground.

I'd want a decent/tropical fan clutch in AZ and clean/decent radiator in any case.

While failure of the temp gauge sender (if it is making a good ground connection (usually yes, tightened against a tapered seat to seal) is not unheard of, it's very very very rare.

If you have good signal back to the connector in the passenger foot well, try another cluster/temp gauge?
Mechanic doesn't want to disturb a bunch of AZ brittle dash plastics? Understandable...
Though the cluster usually comes out willingly.
THANK YOU for your reply. let me clarify I don't buy parts from Napa, Oreilly, AutoZone, etc. I went there to obtain PN's and photos of parts (to support what I'd printed from online sources, eg. IPD, FCP, Tasca, etc. since mechanic kept telling me #460191 is NOT correct part (that's the one that I think is supposed to send coolant temp to gauge, single spade) . He keeps insisting that I need TWO of 1346030 (the ECT sensor, 2 prong) .
IDK what 'tests' he's done to 'prove' these sensors s/b replaced - I think it's more than it's not really OH'ing, sensors don't appear to have been replaced for ages (if ever) so that's his belief on what's wrong.
I brought up Temp comp board because, years ago, my '88 240 - when it seemed to be OH'ing but really wasn't my then mechanic (who has gone to mechanic heavey) did lots of things to resolve - including replacing thermostat, radiator, etc. Matter of fact, local radiator specialist / shop felt that I was sold wrong radiator and needed 'heavy duty' --- anyway after parts store owner replaced radiator and problem still existed parts store owner was the one that said ' temp comp board.' And yep, that was the culprit. My then mechanic voiced no concern about 'oops if I go into dash to replace that I might break the dash cover' (and I've not seen that in any of the comments on TB) - so this mechanic saying that just took me aback.
Since we ARE 'mail order town' for parts - and virtually nothing is overnight (especially not with COVID issue) I'm just trying to ensure that I have parts BEFORE car is taken apart, and then am told, oops, we don't have right parts, or need a connector or whatever. [This is my only car...daily driver.]
As far as I've been told radiator, fan clutch, etc don't need to be replaced. And this was SoCal car until I bought about 5 years ago and brought it to Az.
Thanks again --- y'all are ACES!!!!
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Old 08-06-2020, 05:41 PM   #18
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The temp sensors are located underneath intake runners #2 and #3. They can both easily be removed with a 3/4” or 19mm deep socket and an extension. No need to pull the intake manifold, but pulling the intake tube between MAF and intake does help get more space.

Under #2 you will find a single spade sender. This should have a yellow wire with a female spade connector on it. This is for the dash gauge only.

Under #3 you will find a 2 pin sensor that has the same connector as a fuel injector. This is for the ignition computer and fuel computers only. If the car runs well and gets decent fuel mileage, then this sensor is usually OK.



The temp gauge sensors rarely fail, it’s mostly a connection issue or the temp board in the cluster acting up.
The temp gauge wiring goes through the large gray connector between the intake and firewall (near dipstick). This could be causing issues as well. Your starter wire also goes through this connection, might be good to check if you’re having a no start issue.
THANK YOU so very much for reply, and links. Absolutely same parts I found!
I did just see video that I think showed exactly what you described - about replacing these sensors (without removing everything!)
I voiced concern about temp compensation board (ONLY because it went out on my '88 240, that was also not OH'ing - my then mechanic replaced thermostat, radiator, still had problem. Radiator 'specialist' thought I should have been sold heavy duty radiator, so parts store owner replaced radiator. When problem persisted it was parts store owner that said 'temp comp board' and bingo - that was it! But - that doesn't mean that's problem with my '93 - only that I had some basis for suggesting.
MUCH appreciate your explanaton about temp gauge wiring -- as well as starter wire.
Actually took car to shop due to intermittent starting issue - that seemed to center on NSS and A/T shifter. (ANother thing I've struggled with since I bought this car!) I also just had MAF replaced so hope I notice a difference from that! IMO I should be getting better mileage (best was about 225 miles per tank - I'm sure it's been less than that...)
So, I've ordered ECT sensor, and will ask mechanic about condition of wiring you mentioned.
BTW - IF someone did put wrong sensor in engine - do I have another problem to fix??? I can't imagine how they would have inserted a two prong into opening for single spade.
As always many thanks for sharing your time and knowledge - it's so very much appreciated!
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Old 08-06-2020, 07:03 PM   #19
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Many mechanics are cautious when it comes to dashboard work on 240s, often with good reason:

Abundant NLA plastic brittle and ready to go kaput as well as 240 spaghetti mess of 1960s era wiring stand-alone harnesses layered one over the other that could short out or be plugged in incorrectly as well as previous mechanics hacking/molesting heater fan housings or 'spontaneous-lightening' stereo-install (or similar) wiring under there 30+ years later doesn't help.

Difficult to estimate labor times, car down-times, no fun to be on the hook to replace some broken piece of unobtainum plastic that turns to **** in your hands or have the customer calling constantly for their car back or probability to cause harm/electrical fire with the best of intentions high.
Story of a 27+ year old car generally, but 240 plastic/HVAC boxes/electrical mess under the late model car dashboard doesn't help.

Inland SoCal out of the salt fog or AZ is nice for rust/as long as greased, heater fan motors seem to last well there.
But plastics maybe not so much, though garage & dash blankets help.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~

Have a spare 1992-1993 245/wagon tire size cluster w/working temp gauge.
The halogen main-illumination bulbs on the 1989+ clusters are costly new, but probably good time to replace them with the cluster out...or convert to dimmable/durable L.E.D. if that's a good option/viable.
cleanflametrap.com has good pictorial on all the dash parts & 240 electronics generally.

Wouldn't buy parts until you can nail it down/diagnose more definitely, wouldn't authorize replacing the temp gauge sender on a whim either, would just get the car back for now?

You can probably install a generic VDO 52mm gauge (used from a VW or otherwise) beside the main cluster for water temp using the existing VDO sender I'd guess...or connect one for testing purposes/temporarily without risking much harm.
Easier to read/use the existing 240 water temp gauge in the combined instrument though...188F is about middle of the late model gauge even if it doesn't have #s on it.

Changing out an instrument cluster or even bypassing/removing the temp board or temp gauge is fairly straight forward for even the novice mechanic/ DIYer.

One little note/caveat on the SRS 240s (and basically every OBDI/early-late 90s airbag & newer car ever) & cluster R&R:
ALWAYS disconnect the battery - before removing the combined instrument cluster & verify the airbag warning lamp works before cluster reinstall, else you'll have a perpetually glowing SRS/airbag light that may take more in-depth electrical knowledge/tools to reset...
...for whatever good you think that 27-year-old airbag is going to do for you....maybe something...scared to find out/imagine the situation where that'd be relevant, but doesn't hurt to try to do no harm/put the car back together the way it was as general practice.

MUCH more that's electrical heaped onto the last couple years of 240 on a chassis that's still based on a '67 140.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~

Wish you luck!
You have a very odd writing style. (like I'm one to talk).
*Think* I can get the gist of it, but it makes me a little cross-eyed with the block paragraphs, odd capitalizations & abbreviations.
English appears to be the 1st language from the look of it, but taught/acquired and implemented how mysterious.

Maybe there's some not-totally-creepy harmless/awkward credible & qualified TB nerd/dork that has spare under-dash parts on hand in a large box local to you that can per persuaded to come over with all that junk and diagnose the cluster with the car in your garage (best place for a car to be dead/have downtime).
Believe Lord_Athlon moved from Tucson, AZ to CO though.

Dash work is sort of conducive to qualified mobile mech/electronics/shade-tree guy coming to you more than taking the car somewhere; no toxic fluids to dispose of really, no special tools, no heavy lifting (engine cranes/large parts), just spare parts that don't take up much space on hand, some wire crimpers & DVOM & experience w/diagnostic ability & caution, as well as honesty/reputation to stick to the job without assuming liability to keep costs down (pay cash/car's on your property/your liability.)

Heavy-lifting/shop environment not necessarily required, strictly speaking.
Or just zoom-call/video chat/couple of quality how-to pictorials like cleanflametrap or quaified youtube videos (hard to sort the hokum from the expert) & DIY?

The look on many peoples faces when a 240 dashboard is removed in ~10 minutes late on a friday night w/reassurances to "come back" to finish the job is often pretty priceless.

"sure sure, trust me, it'll all go back in properly the way it was from the factory and get other things tested/addressed/inspected while it's apart with spare NLA parts on hand."
Articulating this or not doesn't seem to change the general mood/owner's facial expression much.
Poor 240 owning sods.
Condolences.
Late is the date for the 240, many jobs that once resembled repairs are more like restorations or mini-restorations now;
That was then, this is now.

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Old 08-06-2020, 07:09 PM   #20
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Install mechanical temp gauge. Same type standard fitting is used.
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Old 08-06-2020, 07:16 PM   #21
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Install mechanical temp gauge. Same type standard fitting is used.
Maybe...
...difficult to say whether embarking on something deviating from the factory plan / adding something different/new is easier/desirable for the DIY novice.

Electrons make it thru the wires pretty reliably often...
...that 240 VDO sender is pretty reliable and '81+ 240s easily accept 52mm gauges that can use that sender anyway...
Just plug into the yellow wire under the dash (don't cut it, just pull it gently out of the connector with the proper tool) and add ignition switched + & - and dimmed illumination for the bulb sounds easier than running some alcohol capillary tube and all that.

That said, functionally, a quick eye glance to check that all is in normal range with the factory combined instrument without having to glance off the main instrument is probably safer/faster to see if there's a problem.
Pity 240s don't have the "coolant loss" warning lamp like 7/9s can.
Pleasant warning to avoid catastrophic damage, though the "radiator with the fan" icon is usually meaningless to many.

Maybe that's not true for 7/9 guys with their more proprietary/non-VDO two-bullet temp gauge sender that isn't the 'common' VDO ohm range and gauge that's basically a gauge-form-factor warning lamp without the bypassable/easily deleted compensation circuit.

IDK what the logical decision tree is for the given owner trying to daily drive one of these 25+ year old vintage RWD buckets...

For DD use I'd rather have the factory gauge work with no compensator board, but that's just me.
Quick reference glance at the dials every so often, continue on.
Especially with soft orange needles and front illumination that's so much more pleasant than the backlit fatiguing instrument panels with their bright blues/other idiotic color combos in the 7/9s & more modern cars.

The late 240 really is kind of the perfect functional but dull revised blend;
shadow box to prevent daytime glare/washout/flat black gauges with phosphorescent orange needles with absolute minimal lumens glaring/blaring backward at you at night on long drives.

Expensive halogen lamps and deleting the green strip thru which the illumination bulbs shine thru of the early 240 is kind of a bummer though.
Layout isn't as nice as the early 240 with the centrally located small tach & orange needles against the soft green background in the "normal" range (red for warning) on the gauges I guess.
Functionally, they got it pretty right 73-80. Maybe could have had the impossible-to-clean flat black/non-reflective coated gauge faces/background of the '89+...worse for longevity/dealing with inevitable dust intrusion (& volvo band-aided needing more light to shine upon them with halogen lamps instead of cheap incandescents to fit in that location without redesigning the housing), but no glare off the dial faces at all/maximal low-stress contrast.

SAAB did a really nice job with the ergonomics of the front-illuminated cluster classic 900 & earlier. Very painless to read at night or daytime, but as usual, more stylish/imaginative than the boring volvo.

Last edited by Kjets On a Plane; 08-07-2020 at 03:59 PM..
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Old 08-06-2020, 08:46 PM   #22
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Also, to the OP, is this a 90+ 7/9 with yazaki cluster?
If yes, and if the idle slowly dips ever more, check the grounds by the headlight and by the ECU.
Also, a loose connection/screw for the ground for the dimmer rheostat ground-dump can cause all kinds of strange issues with the clusters on those 93-94 cars.

That said, I've had the later ECUs lower the idling speed and hunt with the lambda feedback on the LH2.4 940 turbos cars more than others.
IDK if its to do with the programming, charging voltage, and fact that the engine almost stalls when the electric fan turns on or what from the factory with the car having no other discernible faults, even if the gauges all read correctly etc/car in good health, no vac leaks, no other known issues.
Cleaning/adjusting the throttle body seems to help a little.

My very lazy theory (hypothesis?/very non controlled environment laboratory 'consistently' repeatable experience?) is just that the AMM is a long way from the throttle body on turbo cars and there's no other major input for load with LH2.4 (so load change detection fairly delayed), the cooling fan speed 1 draws a lot of current to start the fan, & the E-fan cars run pretty ridiculously hot before the ECU finally kicks the fan on & the ECU program lowers the idling speed ever so slightly more the more the temp rises without the program cutting off after the car reaches thermostat temp, so they idle dangerously/raggedly slowly with the A/C on &/or left sitting on a hot day. (fan cuts on at what? 207F, off at 215F?).

In the case of -91 (& rest-of-world non-A/C cars that retained the mech fan up to 1998) models, the primary fan is mechanical and slowly progressively locks up; no big draw & those cars in good repair run a little cooler/closer to the ~188 T-stat temp, so they idle a little faster (50-100RPM) from what I've observed with the digital tach cheapie-timing-light with the same ECU either way (the ECU is functioning as programmed).

They also didn't revise ECU programming so heavily for emissions in those years...by the last of them they really had them heaped with EGR etc to squeak by CA for turbos cars and turbos don't have air injection/complex/costly smog pumps on the 8V turbo volvo, so tall order to get them to pass low load/idling running at the razor edge with the 8V head/T-cam even with low compression compromising between lean burn & NOX with the injection system/resolution/programming time they had/could afford for models they were about to kill off in the USA market.

In the case of the 850s/WWDs, they have either a hot film AMM and variable resistor TPS or also have a MAP signal that reacts much more rapidly than the hot wire AMM as the sole significant input to calculate load. The brain is also probably enough 'smarter' to idle up slightly when engaging the fan &/or A/C clutch or has more programming revisions to better keep things running smooth & steady, not to mention finer spraying injectors, sequential injection and just higher resolution/more data points for every input from crank/cam signal to everything else.
They were also designed from the start/clean slate with E-fans across the board, electrical system to go with, A/C & modern emissions for all markets in mind by the time we get to the WWDs for the most part with only some variation (optional air injection pump 1997-1998 on all models, even turbo). & there was more programming experience and more advanced electronics from the get-go/those costs were factored in for the new model from inception rather than a revision/band-aid for an old model that was about to be killed off for the USA market.

This is just my hypothesis for the 92-95 e-fan 7/9s, but it's above my pay grade/mental & physical /monetary resources to prove it. Can say older or newer don't seem to have this run-ability oddity.

Your brain burns hotter than mine, you could test this little, possibly hokum pseudo-science pet theory, but if left to idle, I can say a lot of super low mile in good repair 92-95 factory turbo cars run more or less this way, particularly 94-95 with the last revision ECUs that had to pass emissions most stringently of the RWD 8V turbo cars.

It drove me a little crazy too, as even with the T-cam/healthy compression/drawing plenty of vacuum and all, the somewhat slow, ragged edge of lean, hunting on the lambda switching idle (still basically smooth/doesn't have a miss) and near stall as the A/C & fan engaged was a regular irritation, particularly in hot weather if the car was left to heat up &/or with the A/C on.

Since, tuned up/no detectible faults, the newer WWDs and older -'91 mechanical fan cars wouldn't behave that way/seemed to run no fuss/seamlessly for smooth steady idle/no stalls.

I could never say there was anything "wrong" with all those cars with certainty, just bothered me that they all seemed to run more or less that way, and more-so on warm days/heat soaked with the A/C on. They wouldn't outright stall when the fan turned on with the T-cam though.

Why should the last-revision of the RWD cars that are theoretically 'better' run / behave worse in some ways than their older counterparts?
So many assumptions, clear as mud, right?

Wish you luck, can't see/observe as you do/are from your end, but if you can't find anything else, that (repeated?) experience may have *some* relevance, not sure there's more to add to get the factory gauges/senders working as they should within ohm/output voltage range.

Or maybe I just mis-diagnosed an easy/obvious fault in any/all of those cars or didn't follow some update or TSB...didn't work at a dealer and wasn't properly trained to repair those from new-present en masse, so take it with a grain of salt for sure.

My hack fixes/shotgun attempts:
-Install passenger side radiator temp switch plug in lowest available temp/wiring setup from regina e-fan car (88-92C?) or saab T with lower temp switch (uglier, but nice that the fan comes on if there's a little coolant loss being near the bottom of the system) in bottom radiator hose to turn on fan. (effective/ran better/idled similar speeds to the -91 mech fan cars in good repair).
-Increase base idling speed somewhat at throttle body such as that's possible on 2.4/install thumb-screw 2.2 throttle body without allowing fast idling coming to rest off the freeway.
-Install mech cooling fan/pusher fan combo from earlier car.

*may not have passed emissions quite as clean, not sure if I have repeated emissions dyno numbers to back it up...didn't keep data that comprehensive.

Maybe this is all irrelevant now and someone can just hack the ECU with a few key strokes/EPROM socket to turn on the e-fan at closer to T-stat temp ('87C or whatever) now or hack it to not lower the idling speed as much as it does once it reaches operating/thermostat temp if my theory is correct?

I *believe* that the EZK brain controls idling speed/idle motor as well as EGR (if equipped) on the LH2.4 & newer 8V RWD cars, not so much the fuel ECU. Fuel ECU no doubt takes into account inputs from the EZK/idling in closed loop.

Unlike the 2.2 cars (no EGR offered), where fuel ECU controls idle motor, ignition can be mopar MAP based or EZK with the same 2.2 ECU/program, no adaptive memory or OBD function.
Low resolution for ignition, but no adaptive memory and less emission control layers is kind of easier to deal with with 2.2 in some ways.
2.2 cars just have a higher base idling speed with a simple +12V input for A/C idle-up/on to avoid a stall with the pusher fan/A/C compressor engaging/disengaging.
<---Other than lack of OBD & some resolution, prefer 2.2 for long-term reliability/tune-ability/low fuss for that era of old hot-wire LH systems.

Last edited by Kjets On a Plane; 08-06-2020 at 09:29 PM..
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