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1981 635CSi - Ascot Grau

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tschultz
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1981 635CSi - Ascot Grau

Post by tschultz » Wed Jun 05, 2019 12:37 am

So a couple of years ago I stumbled upon an early euro 635 a ways outside of Denver. After some back and forth I ended up looking at it and eventually purchasing it. It was actually a one owner car, the owner's dad had bought it new or very close to new and then imported it in to the US (Fred Minturn). He didn't go into detail and didn't have a ton of records unfortunately.

I just finally got it running and now have enough detail to make a post. Not sure what will happen with this one, but it is interesting enough of a story that I thought I ought to make a project thread.

I had done routine checks online for BMW's just to keep my eyes peeled for anything interesting. Of course this euro sixer was something that piqued my interests. It was multiple hours outside of Denver and I emailed the seller. When I head back from them the seller said it could not be driven. I was confident it wouldn't be sold quickly in a non-running state and might last until the weekend or later. I convinced my wife into joining me on an adventure to go to a new mountain town and take a look at (another) shark. Part of the appeal for her was that it was automatic as she prefers the slushboxes :lol:

So we made the 3 hour trip to the car and the seller was not there but left the keys.

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It was indeed an '81 euro as it it the early chassis, early spoilers but under the hood was a 3.5L engine with Motronic intake manifold. This car has vacuum brakes and I was pretty familiar what to expect having heard about the unique '81 model. The paint was beat pretty bad but the bumpers looked nice and crisp, as did the body. As I examined further, I could not find a trace of rust and I knew that this one was worth saving-- maybe for me in the future, maybe not. I didn't know but felt that it was a car worth saving, especially if I felt like I might be able to get it to run.

A huge oil stain was hidden under the car like the engine was seriously in need of repair. I turned the key and it started right up into a pretty steady idle. That was encouraging. I touched the gas pedal and it stuttered and acted like it wanted to die. A quick check under the hood and removal of the oil filler cap identified that the engine had good vacuum and nothing was out of place otherwise.

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I checked all of the spark plug wires and connection that I could see but nothing helped. The car was able to shift into gear and creep both forward and back, so that was a plus.

The engine bay was super oily but I suspected that maybe it was just an improperly sealed valve cover or similar.

In my sleuthing, I found pictures of the car sitting in almost the same spot 10 years earlier, having arrived from Texas sometime in the early 2000's.
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My brother's X5 4.6iS was the tow vehicle, even going over the Continental Divide and the Eisenhauer Tunnel in Dillon, CO at 10,000'. We made the trek home and I have to tell you, it was sure enjoyable seeing a euro shark nose in my rear view mirror the entire trip home. The X5 looked pretty god towing the shark too.

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Off the trailer in front of my house. It looked pretty happy sitting next to a few other BMW's. Glad it ran because I was able to idle it off the trailer and move it around just a little bit.

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From the build sheet on the rear seat:
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The BMW 635CSi VIN 5581457 was manufactured in May 1981 and delivered on May 08th, 1981 to the BMW dealer Ungeheuer in Karlsruhe, Germany. The original colour was Ascotgrau metallic, paint code 151. The car was equipped with a sliding/vent roof.

Unfortunately there are no details about interior and further special options mentioned in the delivery books. Maybe you are lucky and able to find the so called "Laufzettel" under the rear seat bench (where the colours and options are coded).

The "Laufzettel" additional data decoded:

0113 - upholstery black leather
50.3 - fog lights
54.2 - electric sliding/vent roof
55.3 - green heat-insulating glass
65.2 - both rear view mirrors heated
78.4 - only partially preserved (for the transport of the car)
I attempted to resolve the running problem and spent time swapping parts from my 633 to track down the problem. Spark plugs, CTS, cap and rotor, injectors, AFM, 008 ECU, crank position sensors, but nothing helped with the way it sputtered and hardly revved. Later I tracked down a rare spare 002 ECU and it ran pretty good for about 30 seconds before barely even idling. So I did an oil change, brake bleed and moved it to my side yard where I was going to swap in a full US spec motronic 633 harness. I needed to create a special adapter to the E12 style fuse box to make it work.

Unfortunately after a lot of trial and error and diagnosing, I was unsuccessful.
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About 2 months ago, I decided I needed to just use my research and go for a M1.3 swap from an E34. So I picked up a kit from mye28.com (Matt/bimmerguy) and went to town removing the old harness, installing US spec injectors and fuel rail, crank wheel, and other bits. Upon wiring, I found that I had the uncommon 25 pin harness instead of the common 20 pin harness. This meant more research to identify the pinouts and wire colors. I got that detail from mye28 and tried firing it up.

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I got that swapped (all except for newer water pump which I will still do soon) and went to start the car. Eventually tracking it down, I identified that I had the wrong connector on the starter. Once I plugged that on and cranked for a few seconds, it started right up!


I think it needs valve guides, passenger side window motor replacement, blower motor repair and some other items. Not sure which way I will go with this project or how much progress I will make, but here was some motivation for it.

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Last edited by tschultz on Sat Jun 08, 2019 9:36 pm, edited 1 time in total.

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hornhospital
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Re: 1981 635CSi - Ascot Grau

Post by hornhospital » Wed Jun 05, 2019 1:28 am

Very cool,great find! =D>
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann";'87 325is "Odette"; '93 325is "Elvira"; '95 M3 "Ashlyn"; '95 318is "Bebe"

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Re: 1981 635CSi - Ascot Grau

Post by Shipper 01 » Wed Jun 05, 2019 2:29 am

Nice write up. Keep us informed.

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Re: 1981 635CSi - Ascot Grau

Post by GRNSHRK » Wed Jun 05, 2019 4:15 pm

Great story indeed Tom =D>

Nice to see that you've got another 6er, knowing that you got T-boned in one :cry:

And yes, please keep us posted [-o<
:mrgreen:
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1980 633 CSi
Cypress Green/Pearl Beige
2011 F10 528i
2005 E46 330 Ci ZHP Cabrio
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Re: 1981 635CSi - Ascot Grau

Post by tschultz » Wed Jun 05, 2019 5:20 pm

Thanks guys!

Mileage shows only 117K, so overall it is somewhat low miles even if it has sat outside.

Here are a few interior pics from the original listing
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Being an early model, it smokes a little bit after idling like it needs new valve guide seals from burning some oil. I haven't driven it much-- I went about 2 miles yesterday and made it around the block just fine. It actually drove quite smooth overall and shifted nicely. The brakes need to be worked in a bit before we identify if they are working properly or not. This was the first early model water pump I messed with and is it tight! Getting the fan off was sure a PITA, where the screw on solution is much easier in general.

I found it was a little low on ATF for the transmission but haven't yet found any major oil leakage once I reset the valve cover and gasket. I did shift nicely into each gear, even third. I have wondered how well this gearing is for highway driving. I also need to see if it has sideloader LSD or just an open unit.

3hp22 in '81 635:
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4hp22 in '88 535i:
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G260/6 in '88 535i:
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Initial reaction, it seems to have more off the line pep than my US spec e28 535iA. I haven't brought it up past 45 mph, but the suspension was comfy and shocks seemed to work. It isn't sporty in that regard, but I do have some Recaro's that I could install in it. I also have some new euro headlights that I may install for the proper euro look.

Not sure what is up next, but it was a huge victory so far being able to start up consistently, drive around and shift through the gears smoothly, track straight/steer well, and not leak fluids all over.

I had been aiming to do an all shark announcement for me and my wife (you have may seen in my other project thread) but that didn't work out. I think E24/E28 makes it seem more accurate, but I could have done something similar with picturing the '81:
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GRNSHRK
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Re: 1981 635CSi - Ascot Grau

Post by GRNSHRK » Wed Jun 05, 2019 9:01 pm

Tom, you need to connect with Bert, since he's been performing a "nut and bolt" restoration of the same model, for about a decade :roll:

But since this is a bit of an oddball MY (1st year Motronic but with E12 chassis, vacuum brake booster, etc.) there are likely quite a few things to know and learn that would be specific to only this MY :-k

Once again, nice find =D>
:mrgreen:
Bobbo
1980 633 CSi
Cypress Green/Pearl Beige
2011 F10 528i
2005 E46 330 Ci ZHP Cabrio
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You can never have too many BMW's

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Re: 1981 635CSi - Ascot Grau

Post by zinnocoupe » Thu Jun 06, 2019 2:53 pm

Tom, Congrats. It looks like a great find. I had forgotten you had this. Amazing it has no rust. Nice work getting it running. Looking forward to more updates. Seeing this makes me want to get back to work on my rusty early car.
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1979 Euro 635ci no longer a basketcase, just a running rust bucket!
1977 530i New addition ( nonrunner)
1987 635csi 60K KM Garage Queen

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Re: 1981 635CSi - Ascot Grau

Post by Shipper 01 » Tue Jun 18, 2019 12:41 am

Nice, keep the updates coming.

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Re: 1981 635CSi - Ascot Grau

Post by tschultz » Thu Jun 20, 2019 2:53 pm

I did get the windows all working with some connections being repaired inside the doors.

I pulled it in to the garage yesterday and have started tearing the engine apart to rebuild the head. It smokes badly coming up to a stop light on decel and all symptoms point to valve guide seals. Good vacuum otherwise. Will get the head off and rebuilt and reassembled in the new few weeks hopefully. Going to convert to newer style water pump during the process.

Will get some photos of the process as well. Feel good thinking this guy will get back on the road soon!

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Re: 1981 635CSi - Ascot Grau

Post by tschultz » Sat Jun 22, 2019 1:08 am

Head removal is progressing. Hoping to pull the head off tomorrow morning. I have everything removed except the head bolts. May remove the exhaust manifolds, not sure yet.

Here are a few photos, although they are rather poor quality, you get the idea.

Under the knife, I thought I'd be in this position about a year ago.

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Re: 1981 635CSi - Ascot Grau

Post by hornhospital » Sat Jun 22, 2019 1:28 am

Take the exhaust off. Yes, it's a PITA to do, but it makes the head removal less hernia-inducing.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann";'87 325is "Odette"; '93 325is "Elvira"; '95 M3 "Ashlyn"; '95 318is "Bebe"

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Re: 1981 635CSi - Ascot Grau

Post by tschultz » Tue Jul 02, 2019 12:54 pm

Pulled the cylinder head and found two cracks which would explain some of the burning oil. ](*,)

I have sourced another M90 head with the correct cam and hope to reinstall later this week.

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Re: 1981 635CSi - Ascot Grau

Post by tschultz » Thu Jul 04, 2019 4:16 pm

Some photos of the progress.

I have been removing the old window tint and it is looking better! Here is the work in progress at the moment!

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Replacement Cylinder head from 9 '82 633. Exact same marking on the head and an identical cam. Ready to go back on since I knew the head was in good shape.
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You'll notice it is much cleaner looking than the one that came off (original).

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Cracks in Cyl 4 and 5 for the head that came off. Otherwise it would be usable, shame I may not be able to use it afterall...

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Waiting for a few parts to come to really finish reassembly, but as I mention, hoping to put the head back on maybe this week.

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Re: 1981 635CSi - Ascot Grau

Post by tschultz » Sat Jul 06, 2019 5:35 pm

More progress today. I was able to install the cylinder head on the car and get it torqued down as well as the intake manifold reinstalled.

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The torque specs for the S38B35 engine are what I used rather than the angle method.

Stage 1: 50 Nm = 37 lb-ft
Stage 2: 80 Nm = 59 lb-ft

wait / settling time of at least 15 minutes

Stage 3: 100Nm = 74 lb-ft.

I have the later style water pump on the engine now and was able to modify and mount the AC bracket to work with the M1.3 sensor on the front of the engine.

Where we are now:
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Re: 1981 635CSi - Ascot Grau

Post by Pasocb » Sun Jul 07, 2019 1:32 am

Great progress. Where were you able to locate an m90 head gasket? We are finding sources scarce. Looking forward to hearing about how it runs.
1981 635 Hennarot
1980 635 Polaris (Project)

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tschultz
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Re: 1981 635CSi - Ascot Grau

Post by tschultz » Sun Jul 07, 2019 2:15 am

Yes, I had purchased one a year ago when I was working in my '80 head rebuild. I used elring and new it was the right gasket. Had to send proof of title to get the gasket from Europe.

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Re: 1981 635CSi - Ascot Grau

Post by 86_6series » Mon Jul 08, 2019 1:00 am

So you are torquing step 3 to 74 lbs instead of angle torquing

because your using an elring gasket?

If you were using a BMW m30 B35 head on a B34 block with a BMW gasket

and head bolts would you then use angle torquing?

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Re: 1981 635CSi - Ascot Grau

Post by tschultz » Mon Jul 08, 2019 1:19 am

I have used the torque method before and have had good luck so I would use it for all m30s. Recommended from some users on mye28.com

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Re: 1981 635CSi - Ascot Grau

Post by tschultz » Thu Aug 01, 2019 1:37 pm

I got the car back together and started. Later style fan clutch and water pump in place. and all of it running M1.3 from an E34.

It seems one of the valves is really noisy and I suspect it is the one valve that the eccentric nut wouldn't seem to tighten properly on cylinder 4. will investigate here soon. Took it around the block and seemed to be holding pressure. will inspect for leaks soon here and get out on the road for the first time over 50 mph in the next week.

Here she is

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and the engine bay which is starting to get less and less oily/greasy

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Re: 1981 635CSi - Ascot Grau

Post by tschultz » Sun Aug 11, 2019 2:29 am

Found the nut for one of the eccentrics to be stripped. Replaced that and the engine quieted down nicely. =D>

Went around the block now just over 10 km's. It drives quite nicely and shifts better than I expected. the suspension is sure cushy and soft with whatever sway bars are on it. Found some more parts to go on the car including some BBS RC090's that I think will really set it off. I have contemplated lowering the car too, but we will see what makes sense.


The exhaust sounds great in the revs and really this car is begging for the 5 speed swap. I have pedals and found a G265/6 but it doesn't have the speedo drive to run properly.

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