Failed Compression Test - Terminal?

[flighty]

Hi Guys,

Searching for more of your expertise!

On his last service, a friend off mines 98 E36 failed a compression test on one of the cylinders (its a 6 cylinder 320). Now the thing is he is changing this car and i have the chance to buy it. Should i expect this engine to last any length or is it terminal? He has not noticed any difference in power at all. What typically happens if a cylinder is gone?

Should i stay clear or if the price is right is it worth a punt?

Would anyone have any idea of price, im in Ireland.

The car is in mint condition apart from this problem. Im tempted but have no idea what to expect from this engine.

Cheers,

Raymond

[parolof]

what are the exact readout from the compressiontest? If it's more then 1kg (metric) difference between any of the cylinders, stay away.......

[flighty]

Sorry on the delay in posting back. I will check out those readings before i do anthing. It wont be happening immediately anyway.

Just supposing the readings are ok, what can i expect. Will the problem get worse (loose power maybe?) or will the engine just pack it in some day. I have a 92 318 running ok so dont want to be foolish and buy a heap of scrap. But if the price was right, could it be worth a try? Is there anyway to fix this problem now or is it too late and just a matter of time.

Many thanks,

Raymond

P. S The car is the same colour as yours parolof, very nice pics-nice car!!

[Dave at Pelican Parts]

It could be something as simple as the gaps in the rings lining up. They will eventually go out of line again (if they're moving!) and the compression will come back. But if that's the case, they'll eventually line up again, and...

It could be that a lifter is bad, but you'd probably hear extra noise from that.

It could be that a valve is burned, or is otherwise not sealing well.

It could be that the cylinder wall got scuffed and the rings are not sealing well.

It could be that the head gasket has blown in one spot, and combustion gases are escaping the chamber into the oil or the coolant. There are usually other symptoms that go with this, possibly including overheating, overflowing coolant, "cheese" in the oil (coolant contamination of the oil), and so on.

Most of these problems do not get better without dropping pretty serious cash on the engine. There are extra clues to tell you what of the above (or other possibilities!) is going on, including extra tests like a leak-down test. (That one will tell you if the pressure is escaping past a valve, or the rings and/or oil passages, or into the coolant passages.)

"The price is right" can make just about any of the above fixable--depending on how "right" the price is. After all, you can pick up used 325 or 328 engines and do a swap... Or you can repair the engine as-is for varying amounts of $$, depending on exactly what is wrong with it.

--DD

[flighty]

Hi Guys,

Thanks for your help, Taking the car to see a mechanic this weekend. So see how it goes.

I apperciate your taking time to give advise.

Take it easy,

Raymond