1996 850 Piston Ring Wear Question

RW556 · Post by **RW556** » 14 Jan 2015, 21:57

I just finished replacing the head gasket and now have a lot of oil leaks and smoking dipstick. I cleaned out the PCV system before re-assembly. I had the valves and seats in the head ground. The cylinders had absolutely no ridge. Could the piston rings be that worn to cause that much blow by hence the oil leaks? If the cylinders showed no wear could the piston rings be worn out? Not sure how many miles on the engine, it might not even be the original. Odometer stopped at 230,000 before I bought it. I did not have this kind of pressure in the crankcase before doing the head gasket.

Post by **rspi** » 14 Jan 2015, 22:23

What caused you to need to pull the head?

draser · Post by **draser** » 15 Jan 2015, 07:01

At this mileage you'd expect some ring wear, unusual not to have some ridge though. Try a compression test to find out.

RW556 · Post by **RW556** » 15 Jan 2015, 10:11

I replaced the head gasket because it had blown.

Post by **chrafael** » 15 Jan 2015, 17:38

Don't know so much about Volvos, but when I was a kid the oldtimers used to tell me that you couldn't do a valve job on a worn out engine because it puts pressure on rings that just can't handle it anymore.

Post by **rspi** » 15 Jan 2015, 19:34

RW556 wrote:I replaced the head gasket because it had blown.

I guess we'll start the guessing game...

So it overheated?

Who rebuilt the head?

Post by **oragex** » 15 Jan 2015, 20:37

Maybe the leak is not related to the head gasket, but rather with replacing the pcv box

Normally there's an pcv oil passage inside the oil pan. Did you also check it for not being clogged?

wjhandy850 · Post by **wjhandy850** » 15 Jan 2015, 21:30

I suspect I have the same problem. I replaced head at @160K and I have blow by. I have done PCV and even went to larger heater hose. I can control it a bit by not getting on it so hard. I manage it like I have to avoid high cylinder head pressure.

Post by **scot850** » 16 Jan 2015, 10:33

It would be a good idea to check the compressions on all the cylinders. I had to replace the head gasket on a 760 turbo a few years back as the dealer said the gasket had gone, but it was actually a bad ring on a piston. Another possibility is when the head was being replaced crud got into the cylinder bore and has jammed a ring or scrapped a bore.

Other suggestions are also good.

Did you have the cylinder head faced when you had the valves ground? If not chances are this is your issue and the head is warped.

Neil.

RW556 · Post by **RW556** » 16 Jan 2015, 11:59

I had a local machine shop rebuild the head. they had to replace 2 burnt valves. They ground the rest and the seats and resurfaced it. I was extremely careful to keep everything clean. I don't know if it overheated or not. It is my daughters car and I don't know what happened when the head blew. I will check the compression this weekend and will do the heater hose trick to the PCV system to help it breathe better. If I do have to replace the piston rings, can they be re-installed from the bottom without having to remove the head? I realize I will have to pull the engine, just don't want to remove the head again. Can the ring compression tool be placed at the bottom of the cylinder ?