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240 5.0L swap cooling solutions

BeaverMeat

Active member
Joined
Aug 8, 2020
Location
Vancouver Island
240 5.0L swap sensor solutions

Here is a question for the 5.0 swapped guys. Just got my 5.0L freshly rebuilt... the man did a fine job.

Having some electrical issues with the temp gauge and electric fan. I?m starting to think the temp sender is faulty, or just heavily corroded after sitting for 5 months in open air. At first there was no signal. I grounded the wire and the gauge topped out. Good, that mean?s the gauge works and these is a signal. Cleaned up the contacts and now it tops out slowly when plugged into the sensor.

Next step will to pull it out clean in thoroughly replace tab connector. If that doesn?t work I may need a new sensor. I know the one in there isn?t the original sensor so... what fits in a 1989 5.0L and has the proper resistance for a Volvo gauge cluster?

Second. The electric fan set-up runs off a sensor in the radiator that triggers a relay. The fans would kick on at ~200*. Which is fine for a 5.0 that designed to run at 195*... I?m unsure of that sensor even works anymore... I?m wondering if there is a way to wire the relay into the cluster sender.

Side note: we replaced the temp sensor for the ECU with a new NTK. Going over the sensors I noticed one of the posts was melted. Good thing I still have the old sensor... may need a new plug just to be safe. What would cause that?
 
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When I built my V8 car {350 Chevy} I used a fitting for the cyl head for the Chevy. Drilled and tapped to fit the stock Volvo sender.
I had a custom radiator built, with a well on the upper hose side that I put in an adjustable thermostat in. I also ran a switch inside so that I could turn the fans on if needed. BTW that was 33 years ago,had the car out this AM.
 
LS swap here - I got a sensor adapter for the top radiator hose. Since I pieced the hoses together from little silicone elbows and connectors and aluminum tubes, this just took the place of one of the aluminum tubes. Drilled, tapped for the Volvo sensor. Ran the sensor wire and a ground to it.
 
Took a closer look at it today. It’s just a generic 120*C temp sender on an adaptor. It’s doesn’t have much of a prong hanging down. It did work before the rebuild.

51133770408_d82dc7db59_c.jpg


I suppose the easy thing to do for now is find another generic 120* sender with the same threads. All need is a temp reading before I figure out the fans.
 
I’m in Canada so I’m boned anyways...

Not even going to test it. It’s toast along with the one in the rad. The fans work, but won’t turn on automatically and I know the engine got hot enough.

The Ford is 3/8 NPT I believe and the Volvo is 5/8 UNF?

That doesn’t seem right:omg:

I thinks I’m may just put what was in there already. The sensor that was in there was a VDO 181 120*C 12V. Looks to be 1/8s thread... will have to measure it.

What’s the resistance of the original Volvo sender?
 
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I'm sure you can find an adapter locally. A lot of mechanical gauges come with an assortment of them. Maybe you or a friend has one left over from a previous install. If not you can probably order the kit through a local auto parts store that carries Equus gauges.

Pipe thread is measured differently than UNF.

Here's the temp sender specs.

CoolantTempSenderSpecs.jpg
 
I'm sure you can find an adapter locally. A lot of mechanical gauges come with an assortment of them. Maybe you or a friend has one left over from a previous install. If not you can probably order the kit through a local auto parts store that carries Equus gauges.

Pipe thread is measured differently than UNF.

Here's the temp sender specs.

CoolantTempSenderSpecs.jpg

Perfect! Thanks.

I cross-referenced with a 120*c VDP chart of the type I have and the VDO will read ~5*c higher over the Volvo. Which is ok. I’d rather have it read a bit high instead of lower.

Is there a difference in redblock to D24 diesel temp senders?
 
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Took a closer look at it today. It?s just a generic 120*C temp sender on an adaptor. It?s doesn?t have much of a prong hanging down. It did work before the rebuild.

51133770408_d82dc7db59_c.jpg


I suppose the easy thing to do for now is find another generic 120* sender with the same threads. All need is a temp reading before I figure out the fans.

Doesn't that sender ground through the threads?
 
Doesn't that sender ground through the threads?

No clue... it was threaded into a 3/8 NPT adapter. It worked before the rebuild. Now it doesn’t. Are you saying it’s “sensing” the block temp and not the coolant temp?

Wondering if this is actually the OE D24 sender.

EDIT:

Me thinks it may be.

https://www.ebay.co.uk/itm/Coolant-...40-85-92-2-4-Diesel-744-745-SMP-/313250525009

https://www.ebay.co.uk/itm/New-5233...cco-Derby-Volvo-240-260-D24-NOS-/133217567997

Looks like a VW sensor.
 
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All single wire sensors ground through the threads AFAIK. Don't use thread tape on a single wire sensor. Use liquid thread sealer instead.

I believe that's the sensor for the glow plug timer.

This is the sensor for the gauge for 200 and early 700.

https://www.skandix.de/en/spare-parts/electrics/sender-units-sensors/sensor-coolant-temperature-cockpit-display/1021295/

From my search the glow plug primer has two terminals.

Now that your talking about thread sealer that may be the problem. The mechanic could have used thread sealer on the adapter.
 
Yeah, the tape prevents the sensor from grounding out, so it won't work.

Well... it is grounding out. Very slowly... every time the door chime... chimes, the needle jumps up and up until it maxes out. It’s strange.

Might have to find-out if there is any difference in resistance between the red block and D24 sender. It will take a month to get the part... I’m not waiting that long.

I do have an other cluster laying around from a ‘82 240 turbo that I was going to swap tachs with. I think it may be best to swap out the temp gauge if there is an actual difference.
 
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Other than the manufacturer (VDO or Yazaki) and the face plate the temp gauges are functionally the same from '73 to '93. There is no different gauge for diesel.

If you grounded the sender wire and let the gauge peg you may have damaged it. You're supposed to connect a resistor to test the gauge.

Testing procedure per the greenbook.

Testing temperature gauge
lf the temperature gauge is faulty, the faulty component
(sensor, indicating instrument or voltage regulator)
must first be traced and then the fault
remedied. ln order to trace the faulty component,
two or possibly three resistors are required, one or
two at 40 ohms and one at 282 ohms.

Trouble shoot as follows:
First disconnect the electric cable from the temperature
sensor and then connect up the 282 ohm
resistor between cable and ground.
With the ignition switched on, the pointer on the
indicating instrument should be at the beginning of
the green field (=122?F). Instead of the 282 ohm
resistor, then connect the 40 ohm resistor. The
pointer on the indicating instrument should be at the
beginning of the red field (2480F). With correct
indicating instrument function, the sensor is defective
and should be replaced
 
Other than the manufacturer (VDO or Yazaki) and the face plate the temp gauges are functionally the same from '73 to '93. There is no different gauge for diesel.

If you grounded the sender wire and let the gauge peg you may have damaged it. You're supposed to connect a resistor to test the gauge.

Testing procedure per the greenbook.

I hate electronics. Lol. On some forum threads people said “it was an ok thing to do”. lol

I guess it’s time to buy a fancy multi-meter.
 
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This thing has got me floored. Lol

The sender is working. Did the hot water test, etc, etc. Tested it in the car... works. Ran the car till the tester was at 60ohms and shut it off.

With the ignition on, engine off the gauge quickly goes to where the temp should bb then it slowly maxes out to the top. Start the engine and it quickly goes back to where the temp reading should be then it slowly bottoms out.

I guess the gauge is faulty? Idk wtf... the signal wire shows just under 12v if that means anything.
 
Heat soak will cause the temp to rise once the engine is shut down, with no coolant flow.
 
Heat soak will cause the temp to rise once the engine is shut down, with no coolant flow.

Nothing to do with it... does it when the engine is cold.

Figured it out though. From some internet learnings the I believe the gauge is buggered. The wire reads 12 volts. It should be 10.

Also, the fans sensor/switch on the rad has no resistance.
 
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