Dead M50

[MrMagnum]

Hey everyone,
I've got a 95 520 Touring with a dead M50 motor in it. It's got over 200k KM on it and when I went to start it, it turned over normal once or twice, then seemed to loose all compression. I thought I might have jumped timing, but I'm told these engines are just about bullet-proof. It's been freezing and windy here in Germany, and I'm working nights, so I really haven't taken a look at it yet, I just wanted some ideas.

At the same time, I heard something whirring in the engine compartment, like a bearing or bushing going bad (like in a windshield washer motor). It's coming form the sensor (?) that's at the back of the drivers side engine compartment. It ties into the cooling system somehow? I don't see how that could be causing anything, but I never heard it before that day.

Sorry for the limited information, I just haven't had to mess with this BMW before.

If it is a timing chain, has anyone changed one before on the 24v? Do I need any special tools?

Thanks for the help,

Steve

[tfritz]

try starting it again when it warms up extremely cold weather can make engines sound as though they are falling apart!

[tsweers89]

+1

[smilemore]

my 93 makes the sound that you are discribing i think it might be the preheater for the colant (normal sound). also when my m50 refused to start it was the crank position sensor. it might be worth checkin out.

[HausBimmer]

Very unlikely to be the timing chain - the M20 had issues with the rubber timing belt breaking and could jump timing - but the M50 is solid chain drive. Are you sure you are loosing compression? The heater control valves are in the area you are talking about and have solinoids. Have you looked at your coolant - hope its not frozen - this would definately cause some bad noises. Smilemore's suggestion is the most common source of starting and operating problems with this engine the CPS.

[Jonny525]

my 93 makes the sound that you are discribing i think it might be the preheater for the colant (normal sound). also when my m50 refused to start it was the crank position sensor. it might be worth checkin out.


Very unlikely to be the timing chain - the M20 had issues with the rubber timing belt breaking and could jump timing - but the M50 is solid chain drive. Are you sure you are loosing compression? The heater control valves are in the area you are talking about and have solinoids. Have you looked at your coolant - hope its not frozen - this would definately cause some bad noises. Smilemore's suggestion is the most common source of starting and operating problems with this engine the CPS.

My 94 makes the same noises from the area your describing, and if i remember right it's only when I have the heat going. It's no big deal if it's the same noises I hear.
I also doubt it was the timing chain.
You sound like you know at least a little bit about cars, so I'd assume you'd know what it would sound like if it were your starter solenoid that were bad? If the starter disengaged from the flywheel it could sound like the engine suddenly lost compression seeing how it's not rolling over, but you can still hear the starter spinning which is located right below the crap that makes all the windshield wiper type noise.

[MrMagnum]

Thanks for all the info. Y'all are making me feel better about it not being too complicated to fix. The engine is still turning over, it just seemed like it started spinning easier after it decided not to start. We've still had nothing but bad weather so I haven't been able to put my compression gauge on to see if I've got any problems with that. I'll have to find the crank position sensor and see if I can swap that out for troubleshooting purposes.
I'm normally a Dodge guy and I know how to check the codes on them: is there a way to check them on a BMW without having a code reader?
Once again, thanks for all the help.