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1987 BMW 635 csi engine problem - Help!

This is an SOS to anyone who can shed some light on my hair tearing problem on my recently aquired 635csi BM auto. Here is the story.. bought car which hasnt been in use much over last few months. The exhaust backbox was damaged in transit. Battery was flat. I charged the battery and started the car up, it ran fine although noisy due to backbox needing replacing and it did idle funny at first (hunting revs). I drove it up and down my road before parking back on the drive (luckily) before it decided to stall. When i tried to start it again it wouldnt and it sounded rougher as the engine turned over. Then catastrope struck and from the engine bay came an almightly bang (like a gun shot sound). After gathering up the nerve to try it again it would just turn over but not start. Havent had the guts to touch it since but I know that there is no visible damage to the engine from the outside, ie no cracks, pistons poking through the block, no oil leaks etc. Does anyone have any idea what could have happened? All comments welcomed! Dan.

Reply to
danzuc
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Start at the obvious places, check for fuel and spark. That bang could have just been a backfire, I don't think it means your engine is destroyed by any means.

Reply to
Paddington

Ok, here is something weird. My friend just came over to see the car that ive been talking about and while I was feeling brave I decided to try firing it up and lowe and behold it started without any problems!? I believe that you are right and it was a backfire, but how and why? what should I do to make sure it doesnt happen again? is it related to the engine stalling previously?

Reply to
danzuc

wrote

Some of the problems you describe could be due to an air/vacuum leak. Others sound like the points/plugs.

Floyd

Reply to
fbloogyudsr

Possibly it flooded due to the long time since last run or stopping it soon after starting. This will push a lot of petrol vapour into the exhaust and when it does fire it will ignite it causing a back fire. The situation may have been exacerbated due to the back box damage changing the pressures in the exhaust.

You probably should have cranked it without starting to get some oil round.

Reply to
R. Mark Clayton

Glad to hear that you got your Coupe started. Here are some things to keep your eye on:

Pull the valve cover and make sure the cam oiler banjo bolt hasn't come loose. If the banjo bolt is loose, check the cam for evidence of damage due to oil starvation.

Let the engine idle for 5-10 minutes or so while keeping your eye on the temperature gauge. If the engine temperature gets too high, it's time to replace the hydraulic fan clutch. ($75 or so) You might not notice this until you're sitting in traffic in July (ask me how I know ;-)

IIRC, these engines have nylon timing chain tensioners. If the tensioner breaks, the timing chain will jump teeth and cause massive valvetrain damage. I know of at least one person who has had this happen to him.

Check the steering box attachment bolt. Make absolutely sure that it is in good shape, and securely attached. These bolts have a bad habit of breaking, which causes dangerous loss of steering control. It may have been replaced with a stronger bolt by a previous owner (I can't remember if it was a recall item or not - should have been).

That's all I can think of for now. Hope you get it running tip top and have a blast cruising in your beautiful Coupe.

R
Reply to
Rocketman

I had that once, the backfire blew off a hose that runs into the intake manifold from the idle control valve. Check all the air hoses are securely connected at both ends.

If it's been sitting a while in damp weather you may need to remove and dry out the inside of the distributor cap.

Reply to
John Burns

As the owner of a 1987 528e, I can tell you that you have alot to look over. I have been down this path m,yself. It would be best to check everything as Paddington said. I found that for every 1 japan part there are 4 german parts. Do a full tune up and then start doing some diagnostic testing. If your black box (ECU?) is damaged, replace it. Most of what I thought were fuel problems on mine ended up being electical (relays and wiring) and air related (intake and O2 sensor)

Good luck and go check out some of the web mesage boards as well. If you need some tech>This is an SOS to anyone who can shed some light on my hair tearing

Reply to
bobtegs

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