Engine overheated. Could use some advise. - BMW Forum

NewtoBmw's · 02-03-2009, 12:03 AM

I just picked up a 2001 325ci convertible from my wife's friend. She told me the car overheated from a hole in the radiator, and the dealership told her the engine seized and that she needed a new engine...now the car is mine.

I did a compression test and i got (from front to back) 150/100/45/60/70/140. The car would not start. I cleaned the plugs and put them back in and the car started although it was a little difficult to get started. Once running, it idled pretty good, revved fine and even during power braking it ran smoothly and strong. Back down to idle it was a little rough but ran.

I had no anti-freeze or water in it to see if I was getting white smoke so i'm going to replace the radiator and run it to see what happens.

I'm curious to find out if anyone would have any ideas (although i understand that not being here makes it tough) what might be the problem here. Head gasket, valve job, cracked head, warped block or even possibly some buildup on the valves preventing them from closing all the way which is causing the low compression.

Any ideas or tests that i can do before i rip the top half off would be greatly appreciated.

Thanks

witeshark · 02-03-2009, 12:05 AM

Obviously, an engine that starts and runs cannot be seized up. But I'd say there is evidence of head and/or gasket issues.

marti5 · 02-03-2009, 05:12 AM

Not sure on this but are'nt the readings suppose to be between 142-156, with a difference of 5-10 psi between any cylinder.

FCPGroton · 02-03-2009, 09:53 AM

If it winds up being some head gasket parts. These might help you, just check application guide:

Engine Parts-Mechanical

NewtoBmw's · 02-03-2009, 10:23 AM

Thanks for the responses. I think my best bet at this point is to get the radiator in and run it with water/antifreeze to see what if i get any white smoke.

Yes, i completely agree that it's not seized and i feel bad for my wife's friend because the dealership was clearly misleading her although she was looking for an excuse to get a new car. If it wasn't me with it, one of the mechanics there would have gotten it because that is where they were going with it.

Anyway, i'm not sure of what the compression is supposed to be but i'm assuming you are correct with your numbers since the 1st and last cylinders are in that range leading me to believe that the middle of the head/head gasket got wiped out. I believe that it is common for it to take the hit in the middle of the cylinders.

Thanks again and any more advise would be appreciated.

marti5 · 02-03-2009, 10:38 AM

Aswell as white smoke you may also get mayo in the oil or coolant, which is a sign of headgasket/warped head or cracked head. Hopefully it will just be the gasket, which is what im leaning towards.

Good luck and keep us informed on how it goes.

NewtoBmw's · 02-03-2009, 11:03 AM

Will do and thanks again.

Stupidly, i have not checked the oil yet. I guess i'll do that and then follow with my plan with the new radiator.

Steve323i99 · 02-03-2009, 11:33 AM

Valves commonly bend also due to over heating, might not hurt to check those out too.

NewtoBmw's · 02-03-2009, 05:19 PM

If I end up taking it apart, which it looks like i will end up doing, I'll probably bring the head in somewhere to get re-done. Might as well if it's apart. No?

biguglyfabrications.com · 02-03-2009, 10:31 PM

undo the cylinder head bolts and try to retorque them before doing anything. if it strips just get a used engine. overheated engines that pull the threads out of the block are wasted.

NewtoBmw's · 02-03-2009, 10:37 PM

Interesting. I'll give it a try. Thanks

NewtoBmw's · 02-06-2009, 09:23 PM

Hey Marti, the oil is clean. No milk. I'm assuming that the rings and cylinders will be good and it must be the head/head gasket. Next move for me is to get a new radiator, run it and see if i get white smoke. Either way, it looks like i'm taking the top half apart.

biguglyfabrications.com · 02-06-2009, 09:33 PM

when overheating severely, the rings may loose tension, causing excessive oil consumption when back together.

i got a M54 3.0 back together, and it ate approx a quart per 1500 miles afterwards due to low tension on the rings.

NewtoBmw's · 02-07-2009, 09:43 AM

Wouldn't I see blue smoke from the oil burning and also have low compression due to the rings being loose?

biguglyfabrications.com · 02-07-2009, 09:57 AM

not really..... a quart over 1500 miles is hard to see @ the tail pipe. i think its when the engine is @ cruise when there is high vacuum is when the oil is consumed thru the cylcone seperator (which was new when the head was redone) you wouldnt notice this as much as say you floored it, or revved it @ a stand still..... right then the engine would be at almost no vacuum.... i thought it was a fluke untill the lady kept coming back w/ the low oil light on. over the next 10K miles, she consitantly burnt 1 quart every 1000-1500 miles. normally these engines will only burn a quart or less every 15,000 miles.