E34 M60 overheat damage? checklist?

[Scany]

Hi guys,

Me and a fellow Norwegian here at the norwegian embassy want to start a project with an E34 1995 530i that does not start after the serpentine belt snapped and overheated. The seller says it cranks but doesnt turn over. He has changed the belt and waterpump. Engine got about 165k on it.

After doing a little research on overheating I guess it all depends on how hot it really got. What is the worst scenario here? Warped head? Stuck pistons? Cracked engine block? And what is likely to have happened?

Also, what to look for while checking the car out?

And last, how to diagnose the car? Compression test?

I appreciate any advice you could give us. Thanks!

[tgmeyer]

Engine got about 165k on it.

After doing a little research on overheating I guess it all depends on how hot it really got. What is the worst scenario here? Warped head? Stuck pistons? Cracked engine block? And what is likely to have happened?

Also, what to look for while checking the car out?

And last, how to diagnose the car? Compression test?

I appreciate any advice you could give us. Thanks!

Let's start with 'How hot did it get?' How long did they drive on it while it was overheating? A simple overheat will not [usually] cause damage but waiting for the engine to knock or seize after the overheat is not good. I am ASSUMING overheating refers to the engine...
Warped head is likely. Is that an aluminum head? Look for water in the oil. Compression test will tell you a lot, too.
Pistons are not stuck if she turns over but you wrote she does not crank. Crank and turn over are the same to me.
Lastly, did he check/reset the timing after replacing the belt? And by belt are you confusing the sepentine belt with a timing chain? That engine has 2 duplex timing chains.
TomM

[Scany]

Let's start with 'How hot did it get?' How long did they drive on it while it was overheating? A simple overheat will not [usually] cause damage but waiting for the engine to knock or seize after the overheat is not good. I am ASSUMING overheating refers to the engine...
Warped head is likely. Is that an aluminum head? Look for water in the oil. Compression test will tell you a lot, too.
Pistons are not stuck if she turns over but you wrote she does not crank. Crank and turn over are the same to me.
Lastly, did he check/reset the timing after replacing the belt? And by belt are you confusing the sepentine belt with a timing chain? That engine has 2 duplex timing chains.
TomM

It is the engine that overheated. The V-belt (serpentine) snapped and broke the waterpump. I don't think the timing belts/chains have been affected.

I understand that the engine turns but does not start.

I'm not sure if the head is aluminium or steel. I guess the engine block is alu since we have issue with nikasil coating.

[tgmeyer]

It is the engine that overheated. The V-belt (serpentine) snapped and broke the waterpump. I don't think the timing belts/chains have been affected.

I understand that the engine turns but does not start.

I'm not sure if the head is aluminium or steel. I guess the engine block is alu since we have issue with nikasil coating.

The question is WHY did the belt snap. Something probably seized to cause that. Sounds like bigger issues, IMHO.
Maybe the water pump seized?
The block is aluminum and I assume the heads are, too.
If an engine turns but does not start, it is either not getting fuel or spark. Or the timing is off. Or a head gasket is blown from the overheat. Or the head(s) is (are) warped...or...
I honestly have never worked on this engine and found my information here: http://www.bmwworld.com/engines/m60.htm

[Scany]

Looked at the car yesterday and something seemed a little out of place, so we dropped it like it was hot. Thanks for the help!