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.

> wrote in message
oups.com...
> 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.

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.

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?

> wrote
> 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.

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

Floyd

> wrote in message
ups.com...
> 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?
>

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.

> wrote in message
ups.com...
> 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?
>

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

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.

--
Who needs a life when you've got Unix? :-)
Email: , John G.Burns B.Eng, Bonny Scotland
Web : http://www.unixnerd.demon.co.uk - The Ultimate BMW Homepage!
Need Sun or HP Unix kit? http://www.unixnerd.demon.co.uk/unix.html

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 techincal help here, be as specific as possible with
symptooms and parts. Backfires are not uncommon on 18 year old cars
that site idle for too long :P

On 10 Mar 2005 12:19:11 -0800, wrote:

>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.