M50 broken timing chain woes

My techie's 93 525iX ground to a halt earlier today. Starter spins the
engine really fast and our first guess is a broken timing chain, had
that backed up by my mate's BMW independent mechanic.

I've never heard of an M50 breaking a chain before, it's only done 117k
and there was no noise to indicate a tensioner problem.

Any comments?

--
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

"John Burns" > wrote in message
...
> My techie's 93 525iX ground to a halt earlier today. Starter spins the
> engine really fast and our first guess is a broken timing chain, had
> that backed up by my mate's BMW independent mechanic.
>
> I've never heard of an M50 breaking a chain before, it's only done 117k
> and there was no noise to indicate a tensioner problem.
>
> Any comments?
>
I'd start with: "Oh ********!"
Seriously though, I've *never* heard of an M50 snapping a chain. My own E34
M50 has now done over 340,000miles as of today, and it sounds perfect. No
rattles or other sounds of impending doom. I suppose that being your
mechanic's car, a sticking or bent valve due to infrequent oil changes will
be out of the question too.
Please report back if you do find out what happened as I'm always interested
in problems like this. Hope he gets it sorted out cheaply too.
cheers,
JB

And the service history/oil used is?



"John Burns" > wrote in message
...
> My techie's 93 525iX ground to a halt earlier today. Starter spins the
> engine really fast and our first guess is a broken timing chain, had
> that backed up by my mate's BMW independent mechanic.
>
> I've never heard of an M50 breaking a chain before, it's only done 117k
> and there was no noise to indicate a tensioner problem.
>
> Any comments?
>
> --
> 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

In article >,
John Burns > wrote:
> My techie's 93 525iX ground to a halt earlier today. Starter spins the
> engine really fast and our first guess is a broken timing chain, had
> that backed up by my mate's BMW independent mechanic.

> I've never heard of an M50 breaking a chain before, it's only done 117k
> and there was no noise to indicate a tensioner problem.

> Any comments?

I'm surprised it whizzed round with no noise - I'd have expected the clash
of valves and pistons.

It's not common, but *anything* can and will break.

I went to start my old MG one day. Clunk from the starter, but nothing
else. Thought the drive had jammed. It hadn't. The crank had broken across
the rear main. The starter then pushed the flywheel off centre and jammed.
No other damage, though.

--
*Where do forest rangers go to "get away from it all?"

Dave Plowman London SW
To e-mail, change noise into sound.

On Fri, 03 Dec 2004 22:04:41 +0000 (GMT), "Dave Plowman (News)"
> wrote:

>I went to start my old MG one day. Clunk from the starter, but nothing
>else. Thought the drive had jammed. It hadn't. The crank had broken across
>the rear main. The starter then pushed the flywheel off centre and jammed.
>No other damage, though.

That's some high-quality stuff...

"dizzy" > wrote in message
...
> On Fri, 03 Dec 2004 22:04:41 +0000 (GMT), "Dave Plowman (News)"
> > wrote:
>
>>I went to start my old MG one day. Clunk from the starter, but nothing
>>else. Thought the drive had jammed. It hadn't. The crank had broken across
>>the rear main. The starter then pushed the flywheel off centre and jammed.
>>No other damage, though.
>
> That's some high-quality stuff...
>

Hey, don't you think he has enough problems with his Lucas-equipped MG
without you chiming in? ;-)

Reminds me of the three - count 'em, three - VW GTI's that I owned over the
years. The starter mounting bolt (that's "bolt", singular, not "bolts",
plural) had a habit of coming loose, causing the starter motor to fall off
its mount. Don't get me started on the myriad bizarre engineering foibles
of Volkswagen GTI's. Door handles popping off the car, water flooding in
through the heater vents, flooding in the fuse panel (!!), broken clutch
cables, glued-on wing windows, entire exhaust systems falling off the car,
etc, etc. I don't know why I ever fell in love with those crazy li'l Mk I
GTI's. I guess because BMW 2002's were still pretty expensive back then ;-)

OP, hope you get the M50 sorted for not too many $$$. Maybe it's not as bad
as it seemed at first. I used to have 6-series coupe with an M50 in it, so
I'm somewhat familiar with that engine. I've heard horror stories from
fellow 6-series owners about a broken nylon timing chain guide causing the
chain to jump teeth, in turn causing destructive interference and a trashed
valvetrain. Yours doesn't sound noisy enough to be something that bad.

Glad I sold my M50 long ago. I'm hoping the double VANOS 2.5L in my Z3
holds up.

WOE

My 1986 GTI had none of these problems (but it is a MKII, so maybe they
actually resolved them). I bought it new and still drive it a lot. The only
real problemsI have had with it is I can't seem to keep the horn working. It
keeps getting wet and shorting out.

A fun car to drive.

Dick Schneiders
1991 525i
1999 740i
1986 GTI

>Reminds me of the three - count 'em, three - VW GTI's that I owned over the
>years. The starter mounting bolt (that's "bolt", singular, not "bolts",
>plural) had a habit of coming loose, causing the starter motor to fall off
>its mount. Don't get me started on the myriad bizarre engineering foibles
>of Volkswagen GTI's. Door handles popping off the car, water flooding in
>through the heater vents, flooding in the fuse panel (!!), broken clutch
>cables, glued-on wing windows, entire exhaust systems falling off the car,
>etc, etc. I don't know why I ever fell in love with those crazy li'l Mk I
>GTI's. I guess because BMW 2002's were still pretty expensive back then ;-)

> And the service history/oil used is?

Full history. I know the mechanic who's looked after the car for years.
Always had a decent synthetic.

--
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

Well it IS a broken chain! None of the mechanics involved have seen one
before either. Mega unlucky.

A friend is parting a 525i of the same year and has a good engine so
we're going to swap it over rather than start fixing bent valves. We
could open her up, but for all we know she may even have piston damage.
Maybe it dropped a valve or something and that put undue stress on the
chain, who knows.

--
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

A work colleague's E36 325i broke a chain not long ago. Again, don't
know if that was due to something else going south first. BMW actually
assisted int he cost of repair so I wonder if it was a bad service or
repair or something.