bigcoupe.com

I don't want to modify it.

Absolutely fine if that is what you want.

Bavarian Autosport has a single sprocket part 11311278990 listed.

11311278990 that's for an M30, single cam. I need the sprocket for a dual cam M88.

brickwhite wrote: ↑Fri Feb 02, 2018 8:26 pm Found one on ebay we'll see if it works...

https://www.ebay.com/itm/202208663839

They didn't have it either.... hmmmm.... I may have to go dual chain route.

Upgrade to a twin timing chain.

Re: 85 euro m635csi & m88/3 timing chain - my project

Upgrading to Dual chain would be great if I had someone in the Area but I would have to do this myself.

Anyone have any details on what needs to be grinded/machined away in the head to fit?

Most write-ups out there just state I took it some where and they did it? Not what was actually done.

My old Cam sprockets look pretty good. I have a new intake sprocket and that looks more worn that the Exhaust.

Good Info, Thanks...I'm in the same place. Picked up a 1985 M635Csi. Originally for the motor/trans to drop in my CS but the car was to straight to part out. I'm keeping it and need to find out what I have. Serial number says S38 but its an m88 cover?

I should have all my parts for the chain update in about 3-4 weeks, I'll post details of the process and parts.

Exhaust update.

viewtopic.php?f=2&t=29292&p=214034#p214034

M88 Timing Chain Replacement (without removing the head) Finally starting.....

I took the format for this post from Daniel Leahy and hope to add to it my finds and troubles...

Original post - viewtopic.php?f=11&t=155&p=981&hilit=Ti ... ement#p981



The main parts to replace



I've had the M635 for 5 years and have been scared to drive it because of the lack of timing chain guide history.

I My 1985 M635cs is the B35 version. It had 130K+ miles on all original parts (??). I also decided to replace all the coolant hoses as part of this job since they?d be accessible.

I am not changing to a dual chain setup, I know I know...


Parts Used

11 14 1 726 731 ? Timing cover gasket left
11 14 1 726 733 ? Timing cover gasket right
11 14 1 715 100 ? Main seal in timing cover
11 14 1 315 085 ? Oil pan gasket
12 11 1 252 257 ? 2 ea. O-rings for sealing cam sprocket covers
11 14 1 271 415 ? O-ring, rotor shaft
11 23 1 308 128 ? Hub nut
After market hardened hub from BenGerman on Mye28
? Lower timing chain sprocket
11 31 1 308 550 ? Upper chain guide
? Timing chain
11 31 1 309 945 ? Main chain tensioner rail
11 31 1 317 335 ? Upper chain tensioner rail
11 11 1 308 657 ? Main tensioner rail pin
07 11 9 906 328 ? 2ea. O-ring, main chain tensioner
11 31 1 304 257 ? Idler shaft o-ring
11 31 1 307 408 ? Upper tensioner shaft o-ring
11 31 1 307 782 ? Chain tensioner kit (piston, cylinder, spring)
11 31 1 305 070 ? 2ea. Folding washer for cam sprockets
11 51 1 256 654 ? water pump gasket
11 31 1 308 495 ? Timing chain guide
11 12 1 312 173 ? 3ea. Cam cover gaskets, internal
11 12 1 312 172 ? Cam cover gasket, perimeter

Also doing: (while I'm in there)

- Exhaust header
- full Exhaust
- Drive shaft bearing
- Shocks / struts
- gas tank cleaning, fuel pumps, fuel lines
- Maybe clutch...??? IDK I have it not sure I want to tackle it now.

Tools rented from Greg... Thanks Greg..



Torque multiplier, hub holder and socket....

Initial Disassembly

There is no room to work on this engine. All the parts around the front of the engine had to come off to provide access to the timing chain area and room to work. This is the easy stuff. The only hard part was keeping track of all the nuts and bolts.

I started by removing the hood. I have a 2 post lift in my garage so.. makes life a little easier

1. Removed the fan. Reverse thread, 1?? open end wrench. Had someone squeeze the belts while I smacked the wrench with a hammer.
2. Removed the radiator and fan shroud. I couldn?t find any coolant drain on the M6. Instead, I yanked hoses and let the stuff run all over and make a big mess.
3. Removed the fan belts.
4. Removed the air box, airflow meter, intake assembly (basically everything upstream from the throttle bodies) Left the throttle bodies in place.
5. Disconnected the battery and removed the alternator.
6. Unbolted the power steering pump from the bracket that holds it (and the alternator) to the block, then removed the bracket. Used a bungee cord to hold the pump up and out of the way.
7. Removed the distributor cap and ignition wires.
8. Removed the distributor rotor and the round casting behind it (3 bolts).
9. Removed the crank sensor and bracket that?s bolted to the timing cover, passenger side. (side Note)
10. Removed the pulley on the end of the water pump and then the pump.
11. Removed the pulley from the end of the crankshaft and the harmonic balancer.
12. Removed the Intake and horns from the M88 gives you more room...

Here's Where I'm at...





Not sure what this is.. Maybe JB weld??... on the front cover... that will need to come off...







Initial Cleanup (lots of it)

Working to clean up as much as I can of the front of the engine.

Moving forward.. most of the belts pullies and water pump removed.





Ready to remove the Front hub nut.



But how to position the holder and the torq muliplier...



That didn't work with the hub holder. I was a little concerned the hub turned. I had to find another way to lock the crank and found out later why it turned.



Found it.. 1/2 wrench and plate on back of motor.

Nut is off time to pull off the crank hub..

You are fortunate to have found the single row parts. I am in the midst of converting a single row m635 to a dual row. NLA is the master link chain as well, so more material has to be removed to allow the chain to clear the cam box ( which is where all the clearance problems are ). I've done quite a few and they DO seem to get a bit easier the more I've done for sure. Don't recall if it's on your list, but replace the oil pressure switch while you have easy access. Too bad about the euro snakes missing

The pressure switch on the oil filter housing?

pn- 12618611273

I'll add that to the list along with all the hoses under the intake.

Had some delays on removing the crank hub...

con't

The Front nut is off along with front hub. I found that the wood-ruff Key on the crank had sheered I ordered a new and was able to remove the old key from the crank.







Now to remove the front timing cover.... I was not able to remove it without dropping the oil pan so.

-Remove the oil pan... Which has been a little more difficult than I first thought.

Bring out the hoist..










lift lift lift and slide her out...



I pulled the tranny too... Why not... check the clutch and replace seals.



And now I can get the front timing cover off...





and she's off

Next to remove the timing components..



Most guys cut the guide on the left how else can you get that out?







Haven't tried yet...

If you have to cut the guide up to get it out then how do you get the new one in?

From what I can see in the photos the damage on the crank nose caused by the key shearing is a bit of a worry. These engines have a habit of breaking the crankshaft right there and now you have some stress raisers in a bad spot. I’d suggest having a close look at that before you put the new hub on.

The crank at the hub has some scoring but nothing too bad.

As for the lower guide that's a good question about cutting it. That seems to be the only way to get it off without removing the head.

In both these threads the person had to cut the guide.

- http://www.mye28.com/viewtopic.php?f=5& ... 0#p1456860
-http://home.insightbb.com/~todd.kenyon/Chain.htm

You can pull it out about 10mm to 1/2" but that's about it.

Process con't.

I emailed a couple guys that have done this process with the head on. Only way to remove the lower guide is to cut it.

Cleaned up the gasket surfaces and removed the alternator and AC compressor brackets.

Make sure the Engine is TDC... And lock her in...

I used one of these on the flywheel..





The idler gear must come out. The dowel that holds it is pressed into the head and needs to be pulled out.

- 27mm socket and an axle bolt.









The upper chain guide dowel pulled out by threading a bolt and pulling.



Next to get the sprockets and chain out.

Bend the tabs back that lock the bolts on the cam sprockets.



Take out the bolts from the sprockets and tap the sprocket off the cam.



Removed the idler, upper guide and intake sprocket.



While removing the exhaust sprocket, which I have to reuse since the are NLA I found the Rotor shaft was shattered...





At least I can order a new one. Add it to the list of things I didn't order.

Now to cutting the lower rail. Hacksaw and vacuum for less mess. But slower.





And she's off...



to the crank sprocket.. little heat and a puller she comes right off.





Kind of pointy and gnarled. But I have new..





To get the lower chain guide back on you have to remove the pin and replace. I have heard others have issues getting the pin out. but Mine came out with little fuss. A pair of vise grips and back and forth she came out pretty easy.



Now to clean up all surfaces and wait on some missing parts. I'll then start the reinstall.

I am also going to rebuild the oil pump.

While I wait for parts, I'll start on the front Struts, control arms etc.

-I have new Bilstein sports.
-Lem lower arms
- tie rods, center etc

Very well documented

You might want to consider putting all of these descriptions and photos into one document, for future use, surely others will be down this road at some point

Once again, nice job

Thanks,

When I'm finished, I'll organize it a little better an create a PDF.

You're my hero. I have to tackle this sometime in the next few months. I also won't switch to the dual row chain (but will upgrade the chain tensioner as I feel that is the real culprit to chain failures). To be clear, you never found a source for a new exhaust sprocket, is that correct? I have found everything else (I believe), except for the exhaust sprocket.

Thanks,

Eric

You are welcome. I'll try to get it all together and documented as best I can.

As for the exhaust cam sprocket, I could not find one new. I tried all outlets in US and Europe. NLA

And about the Single chain, Jim Rowe at Metric Mechanic said it's not a bad thing, he had converted to single row on some of his engines.