oil fouling spark plugs,,,,

[covlad1987]

non turbo

need advice on this problem oil fouling on 1 spark plug,,,i had a crank pressure which i sorted out but still getting a bit of a blow back from the dip stick,if 1 of the piston rings is worn could this cause oil fouling on the plugs or is the oil fouling down to worn valve stem seals,it only happens when i rev the engine and seems to stop after the engine gets hot but then that could be down to the plugs burning off the oil on the plugs,,the valve stem seals can thay be replaced with out removing the head any help plz,,,

the car is volvo 850 2.5 10valve yr 1994

got the garage to do a compression test today the test was

cylinders(1)=180 (2)=180 (3)=180 (4)=190 (5)=185

now im not sure if this is bad or good,any ideas if there is something wrong

cheers joe

[Trilarry]

Covlad1987,
You have stated the only 2 ways the oil could get to your plugs. Piston rings and valve stem seals. How many miles do you have? I would do a compression check and see if you have 156 to 186 psi each cylinder. Walmart has a pretty nice compression gauge that's under 25 dollars. If #1 cylinder is way off from the other 4, most likely it's the culprit.

The valve stem seals can not be replaced without removing the head. Check the compression and get back with us.
Tri

[waynej]

Why can't the valve stem seals be replaced without removing the head?
I haven't yet had to do it on an 850,but I've done it on 240's,140's and Chevy's.

[Trilarry]

You are right Wayne, so my answer should be yes it is possible, but usually they are changed with the head off. Here are some instructions with caution not to allow valves to drop down into the combustion chamber.

The first time you do this it will be a learning experience, so take your time. To gain access to these seals the valve cover, camshaft, cam followers (lifters), and valve springs must be removed. The only thing that makes this procedure tricky is that once the valve springs are removed, there is nothing to keep the valve from falling into the combustion chamber. If a valve falls far enough, the cylinder head will have to be removed to retrieve it.

There are two methods used to keep this from happening. The most common method is to adapt an air hose to fit into the spark plug hole in the cylinder head, and inject the combustion chamber with compressed air to keep the valves pinned against the cylinder head. The less common, but equally effective, method is to stuff rope into the combustion chambers through the spark plug holes. These two methods are used on heads that take the plugs on the side like a 240 are other heads. On an 850 I'm not sure how you will keep the valve from falling down since the sparkplug hole is straight down in between the valves not below them like on conventional cars. Tell me Wayne how did you do yours? Thanks for your input and question.
Tri

[waynej]

I have used air,but it always makes me a little nervous. My favorite is surgical tubing.Since this is an interference engine you must remove both cams first. Do one cylinder at a time. Bring the piston about 60% of the way up.Buy a long length of surgical tubing,a maximum of half the diameter of the spark plug hole. Cram in all you can and turn the crank by hand to get the piston as far up as it will go and you should be safe. Make sure you have the crank and cam timing correct when re-installing the cams,or you could bend a valve.
Never heard of using rope. It would be difficult to feed it into the hole and it doesn't compress.

[covlad1987]

hi,,,there is 180426 miles on the clock,,the oil fouling is on number 4 cylinder i only noticed it when the engine stalled and i tryed to start it when i was in traffic, got it going but sounded like a train,so i checked the plugs and found number 4 plug with oil on it,cleaned it the engine ran ok then driving along then over took a car then it started running like a train again oil on plug,,,il get it tested this week,is there any thing i can ad to the oil to stop this ?thanks for your help [/b]