I am currently looking at a Euro 1985 M635CSi. It has a few obvious problems, the main one being that the timing chain jumped a tooth 5 years ago and it's been shelved ever since.

To my knowledge the tensioner broke and probably the pistons damaged the valves, although the engine is not torn down that far.

Before I commit to buying this car (or decide not to) I would like to know if anybody here could direct me to a good price and/or place to get parts for the M88/3 engine, specifically:

Timing chain
sprockets
intake and exhaust valves
anything else that may need work

The cams are a little worn, but I probably won't be changing those immediately.

Thanks.

The S38 (the better known name for the motor you are talking about) is a very expensive motor. A full rebuild of the motor usually runs about 10k, including labor. Parts for the motor are very expensive, as it was a low production engine. Given what you are describing, it will run about 6k in parts, possibly more. No matter where you look, it will be a very expensive project. Given the state of the motor you have, it will cost about the same to simply replace the motor with another S38, since you already have all the electronics.

I'll do most of the labor myself, I see the valves some places run about $70 each (24 valves), I can't seem to find the timing chain and sprockets so easily, is there a good place to find these parts?

I'll do most of the labor myself, I see the valves some places run about $70 each (24 valves), I can't seem to find the timing chain and sprockets so easily, is there a good place to find these parts?

While you are in there, you may as well trick it out a bit by adding bigger valves, bore it out a bit, etc. With this particular motor, it is sometimes cheaper to go aftermarket than OEM. Ferrea valves are a good choice, and having some custom forged pistons will help to reduce the spinning mass while also being significantly cheaper than OEM oversize or standard, Weisco makes fine pistons. For the main stuff, though, like the chain, tensioners, and sproket, all you can do is go expensive, expensive OEM. The dealer can give you list, if you ask nicely. Being part of the BMW CCA helps too, as you get a 10% discount on parts.

Something you may find useful...

http://www.bmwe34m5.com/node/233

Thanks for the information.

I see that I will probably have to rebuild the engine and it's going to be expensive. The car looks to be in good condition in spite of having been garaged for the last 5 years. That having been said, it's a 150k mile car, and the engine needs a lot of work.

There are 4 rust spots, one in the passenger fender and the other three on the underside of the car beniethe the door (the running board bit, not the door).

It has a full set of BBS wheels, and it was imported from Germany (no Cat)

It's an '85, some sort of metalic black with a white lether interior.

I've been trying for a week now to figure out whether, if I buy this car, it will be impossible for me to fix it because I'll have to import every part, or they will cost an arm and a leg. Or once it's together, will the body start falling to pieces. I see one lower estimate for this car goes for about $12,000, but it would be nice if I could get it running and relyable for less than that.

The guy wants $6,500 firm.

I havn't read that pdf yet (I certainly will) but, while custom valves and pistons are extremely tempting, they sound expensive and I'm not sure I'll be able to swing that immediately.

I could pass, or I could buy it and store it, or I could try to re-sell it, but if I buy it I would like to try and get it running. I am curious what people think about whether or not this is a good deal.

Hm. 6.5k for a M6 with a blown motor... The body needs some work... how is the interior? That is kinda the deal breaker, as good M6-es go for about 12-15k. The bodywork is a serious detracting point, as rust is very bad news with e24s.

Like I was saying, the aftermarket valves and pistons could actually be significantly cheaper than OEM parts. (OEM prices for this motor are that high) Plus, you have a Euro, so things will be even trickier. Heck, a gasket set for the S38 goes for quite a bit of cash and has a wait list. This would be a very long term project.

Given your price limit (12k) I do not think you will be able to buy the car and do a rebuild within that budget. Sorry man.

The interior is pretty good and the rust spots were pretty superficial. The consensus when we looked at them was that they would probably be a minor job to fix. But I apreciate your concern there, I'm not sure I would be too worried about these places in another car, but you made the comment that it's bad in an e24.

You did say that the aftermarket prices on valves and pistons might be good, and that is intregueing. I'll have to see if I can find some reasonable alternatives before I make a decision. I looked at the Ferrea website, and will have to do some more research there to get a firm idea about that alternative.

Again, thank you for your input.

A few things need mentioning:

the M88/3 and S38 are not the same motor, the M88/3 has higher compression 10.5 as opposed to 9.8?) which is probably due to the pistons. If going with custom pistons, it doesn't really matter I suppose since you could specify the compression ratio. Therefore, an S38 would cause loss of some of the power.

The cost of custom pistons and larger valves would be pretty high, especially considering the facts that: 1: The block is probably fine, 2: there's a chance that not all the valves need replacing.

Also, I've personally inspected this car, the rust is quite literally nothing to be concerned about, the car's never been driven in the winter. The 4 spots he speaks of is as follows: 1: front fender, mostly surface rust, not really visible easily, 2: under drivers side door. This is the worst spot on the car, it's not bad at all. 3&4: small, small, really nothing rust areas underneath the car. Absolutely not a problem to fix the tiny ammount of rust on this car. It's very likely all that is required is some sanding and painting and possibly other methods of rust proofing. It's all very repairable.

The interrior is all very nice (A bit moldy/mildewy, should clean up though) except the drivers seat is worn from 150,000mi.

Oh and I'll probably be the main mechanic for this car. If I had the $$$, it would be mine. Turbo e30 project prevents that though.

Well, if the PO didn't bend any valves or some such, then perhaps all it would need are some valve seals and a head overhaul, which runs a lot less than a full rebuild. If it is as you say it is, then it could very well be worth it. I guess the chain tensioner let go, causing the jump?

That's the guess.

It could go one way or the other, obviously the hope is that it needs very little, the expectation is that it needs everything.

The S38 (the better known name for the motor you are talking about) is a very expensive motor.

Someone mentioned before, but it's worth repeating. The M88 motor is not the same as the S38; they are siblings but not the same guy.

The M88 was used in the M1 and in the non-catalyzed Euro M635s. It has higher compression, hotter cams and a single row chain that's prone to snapping. It was rated at 286hp.

The S38 is the catalyzed version used in about 10% of the 87-89 Euros and in all the US/Canada/Japan M6s. It has lower compression and a double-row chain. It was rated at 256hp.

...The M88...has...a single row chain that's prone to snapping. It was rated at 286hp.

The S38...has... a double-row chain. It was rated at 256hp.

Thanks for the info about the M88 vs the S38, I only knew about the higher compression and had heard about the chain being different, didn't know the cam was different as well, though it makes sense considering what I have read about the US emissions laws in the early-mid 80's.

So here's a question, the chain NEEDS to be changed (one of the rollers is worn all the way through) is it possible for us to put on the double row chain off the S38?

I don't think internal upgrades (bigger valves, lighter pistons) are really necessary or for that matter, within the budget at this time. Also I think that 286hp will be enough, for a few years anyways.

Thanks for the info about the M88 vs the S38, I only knew about the higher compression and had heard about the chain being different, didn't know the cam was different as well, though it makes sense considering what I have read about the US emissions laws in the early-mid 80's.

So here's a question, the chain NEEDS to be changed (one of the rollers is worn all the way through) is it possible for us to put on the double row chain off the S38?

I don't think internal upgrades (bigger valves, lighter pistons) are really necessary or for that matter, within the budget at this time. Also I think that 286hp will be enough, for a few years anyways.

Sounds like your chain is just like the rest. :-( The bigger problem though is the chain tensioners both on the M88 and S38. The parts are mostly plastic, which as you know gets brittle over time. I just did the work to my car, which has only 33K mi. and was surprised at the condition of the tensioners. Also, if you do the work, S52 parts are an upgrade and I highly recommend it (them).

As far as I know, the parts are interchangeable. In order words, you can fit the double-row chain from the S38 in the M88; however, you should post the question on Roadfly just to get confirmation.

Good luck

Thanks for all the info, this has been very enlightening.

Which S52 parts are interchangable? We'll definately consider them.

The dual-row timing chain was an upgrade for the M88 (my car has it). I think 6500 for that car is highly optimistic. I've seen parts cars with good motors go for $6K. The cost of the rebuild is not trivial, and skimping on this motor is a bad idea.

As for parts, head over to the roadfly e24 forum and search on Steve Haygood. He is extremely familiar with both the S38 and M88 and is a great source for parts.

As much as I hate it, I'd be tempted to part the car. Unless the car is excellent cosmetically (which it isn't from the description), you'll be hard-pressed to get the money back out of it.

I'd offer $4K and walk away if he balks.