Oil in spark plug chamber

elgumby · Post by **elgumby** » 20 Sep 2011, 09:22

Hey Everyone,

I just purchased a Volvo v70 xc 2000. it was riding fine and then all hell broke loose. Abs light, Check engine light, and I kept going into limp mode. I didn't panic and looked over your site and fixed most of the issues. They were related to the ABS module which I had fixed before on my other Volvo. The car was driving a little rough so I figured I give it a tune up and change the spark plugs. The spark plugs were Denso but did not appear to be the correct ones. I bought a 5 pack from Volvo. Changed the oil and then started on the plugs. The 5th chamber from passenger to driver had a spark plug with oil on it. It also appears to be oil on the top part of the plugs where the boot is.

My question:
After reading a few forums it seems that my pcv trap might be clogged. Would this caused the oil to ooze into that 5th chamber?

Thanks,
William

Post by **jblackburn** » 20 Sep 2011, 09:27

It can, or it can be just as simple as a bad oil cap seal. I pulled mine off just yesterday and there's oil all over AGAIN - the cap seals don't last more than a few months at best.

Warm up the engine and pull out the oil dipstick. If you see smoke puffing out of the opening, you're due for a PCV system service. If there's no smoke at all, then just go ahead and replace the seal on the oil cap.

whoa · Post by **whoa** » 20 Sep 2011, 09:34

It's also conceivable for oil to seep through the junction between the two halves of the cylinder head, which is sealed with an o-ring.

First step: put in a new oil filler cap.
Also: assess whether the crankcase pressure really is high: are there actual puffs of smoke coming out the dipstick tube, or just a tiny bit of water vapor? Redo the PCV system if it's necessary.
If that fails: take apart the cylinder head and re-seal it (cheap parts, lotsa labor).

Post by **erikv11** » 20 Sep 2011, 09:53

And seepage around the spark plug seal (o-ring) would be a likely consequence of a clogged PCV.

+1 on change the oil cap seal but here is the bottom line: if you don't know when the PCV was last serviced, and unless the parts look new (check the hose that goes up to the cylinder head from the oil trap), you are going to need to service it soon. For sure do it before you go taking off the valve cover that whoa is referring to. And don't use the URO hoses, they are worthless, get the Volvo branded ones.

elgumby · Post by **elgumby** » 24 Oct 2011, 11:10

I took the car into to the dealer. They state that the oil is leaking into the spark plug chamber because the valve cover gasket needs replacing. I also checked and the dipstick is not puffing any smoke.

Would that gasket cause oil to leak into the spark plug chamber? I don't mean the top part where the boot is I mean within the engine. I might not have made that clear.

Post by **charlyW** » 24 Oct 2011, 11:15

It's possible because the main valve cover gasket is a light skim of silicone style sealant between the spark plug ports there is a set of neoprene style O Ring gaskets. Just to let you know if you attempt to replace either then you will need to remove the timing belt as the camshafts will lift under the pressure of the 10 or 20 valve springs depending on model. There are a few good write ups on how to compress these springs when it's time to refit the cover

whoa · Post by **whoa** » 24 Oct 2011, 11:28

The gasket compound and o-rings Charly is talking about are between the two halves of the cylinder head. The seam between them does not go through the cylinders themselves, so any leak in that gasket would only put oil in the plug wells (where the boots are), not directly into the cylinders themselves. If the real head gasket (between the block and the lower half of the cylinder head were bad, though, this could conceivably happen, though I think it's rare because the passages closest to the cylinders are coolant passages rather than oil passages, in addition to which the oil is under lower pressure than the coolant. So a compromised head gasket usually shows up in coolant-related issues.

So I would ask the mechanic how he thinks the oil is getting into the cylinder.

Post by **erikv11** » 24 Oct 2011, 12:09

elgumby wrote:I took the car into to the dealer. They state that the oil is leaking into the spark plug chamber because the valve cover gasket needs replacing. I also checked and the dipstick is not puffing any smoke.

Would that gasket cause oil to leak into the spark plug chamber? I don't mean the top part where the boot is I mean within the engine. I might not have made that clear.

No, a leaky valve cover gasket (actually it is a seal - not a solid gasket) would not cause oil to get into the combustion chamber. See the previous post by whoa. It could, however, cause oil to accumulate on top of the and under the boot, like you describe in your very first post.

If oil is indeed leaking into the combustion chamber, then a likely (but not the only possible) cause is leaking valve stem seals. What is the mileage on this engine? At startup does it give a puff of blue smoke (due to burning oil)? Or after long periods of idling, say a long stop light?

elgumby · Post by **elgumby** » 24 Oct 2011, 12:58

Mileage is about 170k
Hmm I have not notice puff of blue smoke on startup. I did check the oil dipstick to see if there were puffs from there. None detected.

RedBottom · Post by **RedBottom** » 19 Jun 2021, 21:59

Hey guys I've been reading this thread and I think I'm running into something similar. I went to do the coils and plugs tonight and found oil sitting on top of the spark plug in the 5th cylinder and also all over the top of the engine block. After reading I'm thinking it might be the oil cap seal with it appearing in the cylinder closest to the oil fill. I will be checking on the PCV system tomorrow. My Volvo is at 179xxx miles I just purchased it at the start of this year. I've done a lot of work with my local mechanic friend. Took a long time to get the coils or we probably would've started there. I just wanted to throw my scenario out there with my mileage and see if anyone agrees with the cap seal or if they think it may be the O ring mentioned above. Oh my car is losing about a half quart of oil every month. Don't know if that helps. No other leaks have been identified.