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1985 760- The Jurbo Saga

Thanks for the kind words. Funny you should mention undercoating- I'm currently looking into what it will take to keep it from turning to dust in winter. The undercoating on the car is currently all there, it's just also very crispy. I'm thinking 3M Rubberized Undercoating will be a good option, but I haven't really found much for fluid film/cavity wax that people like over the long term. If anyone has any recommendations, I'm all ears.

Maybe here some useful info. https://www.oldtimer-markt.de/rostschutztest
Its in German but one of the better tests. You can easily see per product what it does. Teil 1 2 3 on the bottom of the page leads you to the 1st 2nd 3rd tests, each a few years later down the road.

Bear in mind that relatively fresh sheet metal has different needs for the wax/grease to stick than a rusted piece of sheet metal in a real old crusty car, like in the test. I'm using either Fluid Film or Mike Sanders.
Can you get some kind of paint-oil? I used "Owatrol" oil, smells line seed based, to freshen up old under body coating before smearing new stuff on it a few days later. Probably similar oils can be found for treating wood paneling and stuff on ships.
 
Maybe here some useful info. https://www.oldtimer-markt.de/rostschutztest
Its in German but one of the better tests. You can easily see per product what it does. Teil 1 2 3 on the bottom of the page leads you to the 1st 2nd 3rd tests, each a few years later down the road.

Bear in mind that relatively fresh sheet metal has different needs for the wax/grease to stick than a rusted piece of sheet metal in a real old crusty car, like in the test. I'm using either Fluid Film or Mike Sanders.
Can you get some kind of paint-oil? I used "Owatrol" oil, smells line seed based, to freshen up old under body coating before smearing new stuff on it a few days later. Probably similar oils can be found for treating wood paneling and stuff on ships.

That article is incredibly helpful, lots of good information in there. I think I'll probably go with the Mike Sanders as well, if I can find a US distributor near me. That's a really good idea re: freshening the undercoating as well. I'll see what I can scrounge up.
 
So it's been almost a year, and I'd like to say the car has been great. It will be someday, but it's still sitting in my garage.

In the interim, I finally got the old wiring harness out and the new one in. This was a good day-

oldharness.jpg


However the car still refused to drive until it was up to temp. More sacrifices to the Old Gods of Volvo diagnosis would be needed. Later that week, I came home to my garage door looking like this:

busteddoor.jpg


And my toolbox looking like this:

socketsmissing.jpg


Hrmm. This stopped play for a while, since I couldn't really do much without even a basic metric socket set. I was mostly disappointed that they took my old Craftsman impact- it was a gift from my dad when I first started working on cars, and I'm a sentimental bastard.

My toolbox now has a cage around it made of 2x1/8" steel bar. Not enough to be theft proof, but delaying enough to allow my alarm to go off before they abscond with my tools again.

Onwards then. Once I got over the theft, I made a vacuum testing tool out of a plumbing cap, an HVAC smoke generator, and an old bike tube-

vactesttool.jpg


This immediately showed what the cold running problem had been the whole time- crap exhaust manifold gaskets. It took about 5 seconds to find the leaks when smoke started pouring out of the manifold to head sealing surface. I popped off the turbo and manifold, and was greeted by this:

exhaustflangebefore.jpg


Not doing much sealing then. I cleaned up the flanges, and installed a YoshiFab fitting for the turbo's drain. I also purchased a Kinugawa feed line for the stock T3. I don't want to battle with the hard lines again, because I am lazy.

cleanflanges.jpg


Cleaned up the turbo and hit it with some cast-iron stove polish. This was recommended to me by a few guys on RetroRides, and they seem to have good results with it. We'll see how it holds up. I'm not expecting much, but it's pretty.

turboprepped.jpg


I also fabbed up a crappy bracket for my shiny new cupholder armrest.

Cupholderinstall.jpg


So now after all that, I need to make a couple changes to my turbo drain hose, and we should be good to enjoy the car for a while. Here's hoping.
 
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TL;DR- It lives, and it's awesome.

Last week I found time to finish tweaking the oil drain and feed routing for the T3, got the Remflex manifold gaskets in to compensate for the slightly warped manifold, and buttoned it all up with some nice shiny hardware.

Ran it up to temp and adjusted the MAF, seems to run nicely now even if it still pulls low vacuum when it's cold. Need to pursue that yet. Unfortunately my stove polish idea for the manifold lasted exactly one heat cycle. Requisite engine bay shot-

Enginebay723.jpg


There are two things that still need doing beyond vacuum leak tracing- you can see in that photo my idiotic vac line routing to the CBV. The unit itself will be getting a bracket that puts it in a less stupid place shortly. You can also see that the Kingsbourne plug wires are exposed to the manifold- some plug boots are on order now to fix that as well.

Now that it was running well, I decided it needed a stress test. Rush hour in downtown Minneapolis on a 95F day with 75% humidity seemed suitable.

Drivingtowork.jpg


Success- A/C blew ice cold the whole drive there and back, and the temp gauge climbed to a max just a couple ticks above the 12 o'clock position and stayed there. I'll consider that a win.

Safely in the office parking garage-

RampParking.jpg


Since I was so pleased with it, I decided to treat it to a weekend clay/polish/wax session. It was nice to finally clean off a years worth of garage dirt and see it as it's supposed to be. It also got some wiper blades that aren't 20 years old, and a few other small things done that actually make it a usable car again. Looks pretty sharp if I do say so myself.

Hoodwindshield.jpg


Now that the motor is healthy, it's uncovered a problem with the AW71. It's hanging on to gears much too long with almost no throttle input, and it shifts harder than the built drag transmission that lives in my friend's G body. It won't go into 4th/OD until about 85mph.

I'm hoping it's a mis-adjusted kickdown cable, so we'll see what I can do about that. If I really can't get it right, this thing might be getting an M46.
 
Great thread, nice car, and excellent choice on the Critical Habitat plates!

I'm convinced I get away with more with those plates :lol:
 
Great thread, nice car, and excellent choice on the Critical Habitat plates!

I'm convinced I get away with more with those plates :lol:

Thanks for the kind words- when I saw that they still had the malaise-style CH plates I knew I had to put them on this thing. I'll never feel bad about giving the money to conservation efforts either.

More AW71 fun- kickdown cable is toast, got a new one. It's being a real pig to get out of the transmission. Gotta spend more time under the car covered in ATF and make it right, which means finding taller jack stands so I can improve access.

Also, messed around with various hose sizes and was able to fit my Forge CBV in a less stupid place than facing the fan, while keeping my stock intake boots and piping. Hooray.

In case anyone is interested, I just needed two hoses to get the radiuses right and cram it under the intake piping- parts were Napa NBH 8977 and NBH 9277, as well as a brass hose barb from the hardware store.

splitter.jpg
 
In our last episode of "Man Has No Idea What He's Doing", I noted that the kickdown cable was broken on this car. Well, after fighting the old cable tooth and nail, I fixed that with a new Febi item-

IMG20190812183229.jpg


Checked gasket fit (I wasn't convinced of the quality of the Meistersatz stuff from FCP, but it fits just fine) and treated the pan to an Allison magnet and new drain plug-

IMG20190915170216.jpg


Then cleaned the pan as well as I could, refitted it, and adjusted the new cable. This was my first attempt at crimping the little ferrule, and I got it almost dead nuts on the 2 in. (+/- a few fractions) spec listed in the Volvo Transmission manual. Excellent.

IMG20190922160050.jpg


Refilled the transmission with a few quarts of Valvoline's Dex/Merc, and took it for a very VERY cautious test drive. Well, it started out cautious anyway, but the car was behaving itself so well with the cable fixed I couldn't help but give it a run out on the highway. 4th now engages at ~62 mph, and overall it drives much more like a big luxury car should. However, during my drive, it started to rain. As I pulled off at my exit, this happened-

IMG20190922163538.jpg


Well balls. That'd be a stripped wiper arm or standoff then. Let's investigate.

IMG20190925190541.jpg


Is that JB weld holding the wiper to the motor? Of course it is. Do I have an invoice for new wiper arms in the big pile from the previous owner? Of course I do. I admit I feel a bit dumb for not noticing when I replaced the blades last month. Total garbage.

So then, after removing the previous shop's "handywork", I drilled and tapped each wiper arm to accept a 10-32 set screw. I used a 1/4 inch, in case anyone needs to replicate this on their own car.

IMG20190929161433.jpg


The wiper boots were also very crispy upon removal, so they got fed over a couple days with some rubber restorer I had on hand-

IMG20190925200918.jpg


Then the wiper arms got a fresh coat of black and clear before going back on the car like so:

IMG20190926170336.jpg


Much better.

I started using the car daily with the goal to put at least another 1000 miles on it before the end of the year. The next day, one of our local constabulary alerted me to a brake light problem I was having. I had noticed the warning light on and off periodically, and I had assumed it was a bulb failure relay problem. It was not.

IMG20190928181148.jpg


What the actual hell is this? Why do? What is? How even?

Once I got over my initial *mild* irritation, I noted that the brake light bulb in the same location on the other side had been removed, but at least that holder wasn't still stuffed full of old bulb. New bulbs, clean contacts, and one new holder later, the warning light is out and everything is fully functional.

I'd like to say I'm going to start ramping up the projects on this to the big stuff like cam/turbo/etc that I will do eventually, but I'm honestly just enjoying it like it is right now. Feels good to actually use it like a car instead of treating it with kid gloves like I had been. In the meantime, I'll keep making small improvements, and the next project is definitely rustproofing.

Minnesota winter does loom, after all.
 
So then, since I ended up buying a 2012 Civic to take over DD duties, the 760 has been tucked away safe from the salt and other drivers with bald tires. Cleaned it up late last fall and took it for a last drive- it was looking pretty sharp.

IMG201910261803501.jpg


Now that it's warming up again, it was time to get to work on the main issues it has- a very poor cold idle, a known bad O2 Sensor, soft MAF-to-Turbo hose, a weeping water pump, and a total unwillingness to get past the 30% mark on the coolant temp gauge unless it's 90+ outside and I'm running the A/C.

So then, is the gauge lying? Nope-

TempTest.jpg


That's good then. Fired up the parts cannon once more, got a water pump, MAF hose, coolant temp sensor, O2 sensor, and the correct 87C thermostat. I have the upper and lower radiator hoses, as well as a new AISIN fan clutch in my pile of parts already, so those will go on at the same time as the water pump.

Partspile.jpg


I then set out to do the simplest things first, mostly because I wanted to see their effect on the car's running. The MAF to Turbo hose has always looked like this:

intakehose.jpg


Which I'm guessing is the result of the profoundly clogged PCV system that the car had when I got it. I had a much smarter person than I evaluate the turbo itself last summer as the other possible culprit, but the old T3 still seals ok surprisingly. Let's try the new hose on for size-

doesntfit.jpg


Or not. Really disappointed in IPD, this is pretty dire. Don't buy the MTC version of this hose if you have an early 7er I guess (or anything else MTC, now that I think of it). Standoffs and ports in the wrong place entirely, to say nothing of the fact its four inches too short. Oh well, the old one will go back in place for now while I save my pennies for the swanky Do88 silicone version or get sick of it all and decide to roll my own.


Since I had limited time left in the garage, I decided to replace the next thing on the list- the O2 sensor. No pics of this unfortunately, as access is an absolute nightmare, and I was too busy swearing and cobbling together the right combination of extensions and u-joints that I thought would free the old sensor. However, it did finally yield, and it is certainly past it's best-

02sensor.jpg


Looks like most of the other O2 sensors I've pulled in the past, just a hair crispier if anything. Tossed the new one in.

The million dollar question then- did it fix the cold idle issues?

No, but it did improve them substantially! With this replaced, I have also now noticed a small leak from the turbo to downpipe flange. Looks like new studs and nuts for the downpipe connection will be next on the list.

The good news is that instead of the car now taking 5-6 minutes to be driveable, it took less than 2. In addition, the all around driveability of the thing is dramatically improved- boost comes on faster and hits much harder, the tip-in response is very much improved, and generally it feels like the mixture is much closer to what it should be.

While I hated driving on a coolant weep that I knew about, I was so pleased with the change that I couldn't resist topping up the reservoir and taking it to procure some essential isolation supplies.

success.jpg


My beverage of choice seemed an appropriate errand for such a fine Swedish machine (yes, Linie is Norwegian but it's my favorite. Just don't tell that to my grandfather from Sweden).

Hoping to get the cooling system sorted in the next few days. I hope too that you all are staying healthy and practicing the same kind of social distancing via garage time.
 
This constitutes part 1 of a big thread catchup- this work was done a while ago.

So since I've had plenty of time to work on the Volvo, I decided to address a major annoyance of mine- the cam-driven distributor. I've rebuilt this one twice now, which is always a pain. It will seal for maybe a month or two, then start leaking again. It involves my stupid homebrew jig to drive out the pin that holds the drive gear to the shaft:


IMG20200408191240.jpg


It's obnoxious and I hate it. So, what to do?

Well, under a freeze plug (under the intake manifold) runs the intermediate shaft. If I'm luckily, there will be a gear there to drive a 240 block mounted distributor. I can then plug the back of the head with the appropriate oil seal and retainer and never deal with this again.




So then, what's the verdict?

IMG20200415170431.jpg



I have the geared shaft! Result. I ordered up the requisite 240 Turbo ignition components:

IMG20200426163919.jpg


Then cleaned up the used distributor:

IMG20200427190621.jpg


Not perfect but with a new cap and rotor it'll be fine for testing. I then set about relocating the ignition coil from the left side of the engine bay to the right side. Stock location is here:

IMG20200426163605.jpg


The coil will live where the non-operational vacuum pump lives now:

IMG20200426163641.jpg



So removed the line and plugged it. I'll remove this line completely if this is successful and the car doesn't flip out with no pump.


IMG20200507180714.jpg


Then mounted the coil and ran some 16 gauge wire and loom to the new position:

IMG20200428184046.jpg


I'm going to try to test fire the thing, then tidy up the wiring with the appropriate clamps and such. I then soldered in the new wires, covered them in silicone grease, then heat-shrink, then wrapped in electrical tape and loom for some abrasion protection.

IMG20200502191039.jpg


IMG20200502194912.jpg


Then I proceeded to clean up and repaint the used 240 ignition coil (the ends are different to the 740/760, so it had to be swapped as well). 15A even included a replica Bosch decal for maximum nerdy- it's little but stuff like this makes me happy.

IMG20200510160136.jpg


Then I had the thought that I should check the injector seals, as they're a common source of subtle vac leaks on this engine:

IMG20200507190109.jpg


Yup, that will be done for then. All the pintle caps were cracked as well, so I have new seals, nylon spacers, and caps for them on order. While I'm waiting, I kept thinking how nasty the intake manifold has always looked.

IMG20200510155150.jpg


A couple hours with some very weak aluminum brightener, and it looked a lot better. I also took this opportunity to dress the injector sealing surfaces with emery cloth- they were looking rough.

IMG20200510171242.jpg


Again, not perfect, but I'm much happier with that, especially the injector sealing surfaces.

Now I'm just waiting for the injector parts, and we can try a test fire with the converted distributor.
 
Part 2 of the big catch-up:

So then, proceeding with the block-mounted distributor conversion, I had to check that the hall sensor wiring (for ignition pulse signal) would reach the new location.

Luckily it did:

IMG20200515144116.jpg


However, you'll notice I had to clearance the rear timing cover in order to get it to fit. Still not sure why, as most Volvo 240's from '86-'88 had LH2.2 and the distributor in this location. Part numbers for the timing covers are the same for those cars and mine. Strange.

Since the test fit was looking good, it was time to re-assemble the intake and put it back on, so I installed the new o-rings and pintle caps on the injectors. I regret not painting them when looking at this picture, but at the end of the day the chance of me masking something wrong and toasting an injector just seemed like an unnecessary risk.

IMG20200513163409.jpg


Then finished cleaning all the hardware up and put the intake manifold assembly back together-

IMG20200515153000.jpg


Definitely an improvement. The intake mating surfaces on the head were looking nasty, so they were cleaned up:

IMG20200513165924.jpg


IMG20200513171850.jpg


And then it could all go back together for a test fire:

IMG20200516214527.jpg


The test start, however, was a bust. It would crank freely but the fuel pumps weren't turning on. I then learned that if anything in the ignition system pre-distributor isn't working correctly, LH 2.2 automatically will not turn the fuel pumps on. It's a nifty safety system.

I had two main concerns here- that I had somehow cause a short in the coil wiring I extended, or that the Hall Sensor wiring had broken internally when I relocated it to the drivers side of the block instead of its normal home on the back of the head.

So then- let's break out the multimeter and test the hall sensor wiring first. According to what I could find, the three pins on this connector are (from left to right) power, signal, and ground. With 12V applied, we should get 11V between the power and ground terminals and 5V between the signal and ground terminals.

IMG20200517170519.jpg


That's good!

IMG20200517170544.jpg


Also good.

I also checked the coil wires for continuity, and those are looking good as well thankfully. That leaves two possibilities- the distributor is timed incorrectly to the engine, or the hall sensor is outputting no signal.

To test, I just plugged the hall connector into the old distributor on the back of the head. Turning the key, I could immediately hear the fuel pumps come on- so it looks like the "good used" distributor I bought isn't outputting signal correctly. Lame.

I set about finding another distributor, but that's been a bit of a task. I think I have one on its way to me now, so I'll have to wait before I can test firing again. I also re-timed the motor and distributor just for good measure, and in the process threw some paint on the timing cover and installed a new fan clutch that I've had laying around forever.

IMG20200521184610.jpg


IMG20200524144222.jpg


IMG20200521184616.jpg


IMG20200524185735.jpg


So at this point I'm biding my time until the new distributor gets here. I'd be more anxious about getting it done, but my hobbies seem like much more of a luxury than normal at the moment- that point was driven home when I went to go fill up the daily at the local gas station:

IMG20200529074429.jpg


Pretty surreal stuff to see in your own neighborhood.

At any rate, I'm looking forward to getting this back on the road, but staying safe is kind of the priority at the moment. The Volvo is providing a welcome distraction at least!
 
Part 3 of the big catch-up:

When we last left the 760, it was sitting in my garage as I searched for a replacement distributor to get it back on the road. I first tried the junkyard, but someone had broken the hall sensor connector off of it. Too bad it was the only LH2.2 240 being broken I could find in the state:

JunkyardDistro.jpg


I finally found one, but shipping would take a while, so I turned my attention to some cosmetic frippery- the b-pillar trims. They have looked like this since I've owned the thing: 


DoorTrimBefore.jpg


Broken clips and peeling pleather is not a great look. The mounting points for the top and bottom screws were broken as well, so I sourced some new pieces and wrapped them in a grey faux suede:

DoorTrimComparison.jpg


Not too bad for my first time wrapping anything. 

Back on the car- 

Doortriminside.jpg


A vast improvement for the $35 it cost me in materials. 

Doortriminstalled.jpg


I also have a new drivers door seal to go in at some point, but for now I'm happy with that improvement.

That (and getting my motorcycle ready for the year) took up enough time that the replacement distributor showed up:

Newdistributor.jpg


Timed it up and the car started first try. Nice! Set the timing to 14* BTDC and it runs great. Also surprising- the car doesn't seem to care at all about the vac pump being deleted.

Now knowing that this was going to work, I removed the leaking head-mounted distributor and installed the correct oil seal. I also purchased a seal retaining plate from 15A on Turbobricks, as these seals are known to get pushed out on Turbos if the plate isn't installed. 


Retainingplate.jpg


Duly installed- and I have finally eliminated that god-awful head mounted dizzy from my life forever! No leaks, no rebuilding every 6 months, cheaper dizzy caps and rotors, and to top it all off it greatly expands the cam choices I have for this car (the old distributor requires a slot be milled in the back of the cam for it's drive dog to slot into). This left the engine bay looking like so: 

Finishedenginebay.jpg


Since I had finally replaced the fan clutch as well, I took it out to sit in traffic on a 90F day. As a bonus to replacing it, my car finally reaches its full operating temperature and stays there- even with the AC on full blast.

Running.jpg


Considering the car would never get past 1/4 on the temp gauge before, this is good news. I figured it wasn't hurting things too badly to run it cool, but at the same time I like knowing now that it's working as intended. I also took the opportunity to upgrade to the "Tropical" fan clutch available from IPD USA, so it will keep things appropriately cool in our hot summers while still letting the engine work as it's supposed to.

That's all I have for now, which considering how long it took to happen seems a bit disappointing! Learning as you go does tend to slow things down a bit. At any rate, we'll see how many miles I can put on before I tear it apart for the next improvement.
 
Part 4 of the catch-up:

So a small update- since my last post I've mostly been just driving the 760 and thinking about what needs improvement on it next. It needs (at least in my addled brain) a total cooling system refresh, a replacement for it's soggy MAF-to-Turbo inlet hose, and a couple of small oil seeps sorting. I'd also like to refresh the motor mounts sooner rather than later. None of those things are as urgent, however, as the fact that I have always hated the US-spec early steering wheel. Duly replaced with a Momo Monte Carlo in 350mm-

IMG20200920165116.jpg


Which has done wonders for my enjoyment of the car. The stock bus-sized non-SRS steering wheel was just too big to use comfortably, and the tiny increase in low-speed steering effort is really the only downside.

Took it to visit some of its great-grandchildren while picking up an oil filter at the local Volvo dealership-

20200905145954.jpg


And picked up a swanky Do88 Silicone intake hose to replace the soggy stock item. However, there was one large-ish problem:

20200914182448.jpg


There is no take-off for the PCV system on the replacement hose. The stock part for reference: 

20200914183940.jpg


That 5/8th inch take-off needs to be there, or the PCV setup won't work as factory. Since I'm not willing to re-design the PCV system entirely right now, I'll have to find a way to install a take-off on the Do88 hose.

So while I've been thinking about that, we had an extremely severe thunderstorm come through- hail, high winds, and a crazy amount of rain. This began a run of mildly bad luck (and some very good luck). When the storm hit, the 760 happened to be parked outside, and I couldn't get it inside before power lines starting coming down, etc. It got some minor hail damage to the chrome window trim and the trunk lid, but otherwise survived unscathed- not a bad result for a storm that made the sky look like this for several hours:

20200814202753.jpg


When the storm cleared, I immediately put the 760 back inside, where it would stay while I dealt with the insurance- our roof on the garage and the house were damaged pretty severely and merited replacement. The work was done:

20200905171702.jpg


However in my infinite wisdom I had left the 760 in the garage to "protect" it from the construction activity. This proved to be a bad idea, as I came out to the garage the following day to this:

20200906085648.jpg


Poor little guy, just can't catch a break. That picture doesn't show the larger pieces of debris that had fallen and slightly dented the roof and trunk. The paint is also looking worse for wear, but there was only one thing for it- get to cleaning!

Which got us back here:

20200627134926.jpg


Which isn't awful.

I also cleaned up the engine bay, going from this:

20200627122045.jpg


To this:

20200627134756.jpg



Which also isn't half bad. The car continued to behave itself, so it was graced with an eggcrate grille for that extra bit of 80's turboness:

IMG20200808145004049.jpg


I'd still like to move the front "Jurbo" badge from the chrome grille over to the eggcrate, but someone has epoxied it on at some point, so that'll be a project on its own.

It's also been used for a few day trips with my wife, like the one from this weekend. Packed a picnic lunch and drove to the border between Minnesota and Wisconsin- the St. Croix River:

IMG20200919142041.jpg


It didn't particularly care for the constant brake use down the river bluffs, but I have an upgrade in mind for that soon anyway.

As of this evening it's still working well, tucked up in a freshly re-organized garage:

IMG20200920165600.jpg


I'm hoping to keep working on small things here and there before the snow hits, so I either have a week or two months- there's no rhyme or reason to it. Guess I better get to work!

That brings the thread current to 9/20- also, if the writing sounds weird it's purely because I carried it over from my thread on RetroRides UK. Also because I am not a writer, I'm just a nerd with an old car.
 
Nice work, car is looking great and good to see someone else keeping one of these early 7 sedans on the road.

I think that auxiliary electric vacuum pump was only used on the early 7 series turbos with ACC climate control, but they got rid of them in the later years so they must have figured out they were unnecessary. I had an '84 764T with a B23FT that had one but all the later turbo 7's I have had or seen, '86 on, did not.

Presumably the idea was to provide a vacuum source to keep the vacuum-actuated HVAC functions working during situations when the turbo was creating positive intake pressure. I guess they must have determined that the big vacuum reservoir inside the front bumper, with a check valve, was sufficient for that purpose even without the pump as long as the driver wasn't switching HVAC modes repeatedly while keeping pedal pinned for minutes at a time climbing a mountain pass. Pretty corner-case usage scenario. ;-)

In short I think you'll find you can keep that pump out of the car permanently with no meaningful effects, as long as the check valves in your vacuum system are sealing well and the system isn't leaking. Plus you said the pump was already dead anyway. Certainly there won't be any ill effects on the electrical side from its absence.
 
Nice work, car is looking great and good to see someone else keeping one of these early 7 sedans on the road.

I think that auxiliary electric vacuum pump was only used on the early 7 series turbos with ACC climate control, but they got rid of them in the later years so they must have figured out they were unnecessary. I had an '84 764T with a B23FT that had one but all the later turbo 7's I have had or seen, '86 on, did not.

Presumably the idea was to provide a vacuum source to keep the vacuum-actuated HVAC functions working during situations when the turbo was creating positive intake pressure. I guess they must have determined that the big vacuum reservoir inside the front bumper, with a check valve, was sufficient for that purpose even without the pump as long as the driver wasn't switching HVAC modes repeatedly while keeping pedal pinned for minutes at a time climbing a mountain pass. Pretty corner-case usage scenario. ;-)

In short I think you'll find you can keep that pump out of the car permanently with no meaningful effects, as long as the check valves in your vacuum system are sealing well and the system isn't leaking. Plus you said the pump was already dead anyway. Certainly there won't be any ill effects on the electrical side from its absence.

That's good to know- I have noticed that in certain conditions my brake assist is not quite what it should be (ie. climbing a long steep hill, then having to brake continuously while coming down the other side) but that would make sense based on it's intended function. I'll consider getting a more modern replacement if it becomes an issue- appreciate the kind words otherwise!
 
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