oil on spark plug threads
08-14-2001, 06:40 AM
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oil on spark plug threads
So today I decided to change my plugs. When I pulled plug #1 the threads were covered in fresh engine oil. The good news is the oil looks pretty clean. The bad news is, I don't think it belongs there. 
So, it seems like there'd be 2 ways for oil to get there; by blowing by worn piston rings, or by dripping by worn valves (sleeves?) when parked. The plug tip looked normal (no burned oil, no more deposit than the other plugs), which makes me think valves. Does this seem right? I think either way is bad news. Any other (less expensive) reasons for this to be happening? Should I schedule a wallet-ectomy at the porsche doctor?
So, it seems like there'd be 2 ways for oil to get there; by blowing by worn piston rings, or by dripping by worn valves (sleeves?) when parked. The plug tip looked normal (no burned oil, no more deposit than the other plugs), which makes me think valves. Does this seem right? I think either way is bad news. Any other (less expensive) reasons for this to be happening? Should I schedule a wallet-ectomy at the porsche doctor?
08-14-2001, 10:10 AM
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What you are probably seeing is anti-seize lube that was applied to the threads of the plugs. This was originally recommended by Porsche back in the 80's but has since been issued as a service bulletin to NOT do.
If you wipe it on a clean paper towel, does it look silvery? In any event, I doubt you have a serious problem, or you would have fouled plugs indicating such. Just wipe as much of the stuff off of the threads and re-install them.
Not sure why Porsche went away from the requirement of AS lube, but most plugs today already have a fine application of oil on them, so seizing is no longer common.
The service bulletin does not provide an explanation, but was originally applicable to 911's, and subsequently passed on to all P-cars. Maybe that lube stuff, if applied to heavily, finds its way into the cylinder, and has negative impact on rings, etc.
If you wipe it on a clean paper towel, does it look silvery? In any event, I doubt you have a serious problem, or you would have fouled plugs indicating such. Just wipe as much of the stuff off of the threads and re-install them.
Not sure why Porsche went away from the requirement of AS lube, but most plugs today already have a fine application of oil on them, so seizing is no longer common.
The service bulletin does not provide an explanation, but was originally applicable to 911's, and subsequently passed on to all P-cars. Maybe that lube stuff, if applied to heavily, finds its way into the cylinder, and has negative impact on rings, etc.
08-14-2001, 01:40 PM
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Tom, that is part of the anti-seize controversy.
The issues are getting too much anti-seize on the plug so it gets in the cylinder (that seems easy enough to avoid and not a big deal even if a little got in) and over torquing the plug thereby striping the aluminum head threads because the lube reduces the turning force required to get the same clamping pressure.
Over torque is easy enough to avoid also if you are aware of it, after all this is only a plug not a head stud, and I like the idea of having anti-seize preventing any galling of the aluminum threads. Once aluminum galls you have a real mess and will become very familiar with a product called heli-coil.
The issues are getting too much anti-seize on the plug so it gets in the cylinder (that seems easy enough to avoid and not a big deal even if a little got in) and over torquing the plug thereby striping the aluminum head threads because the lube reduces the turning force required to get the same clamping pressure.
Over torque is easy enough to avoid also if you are aware of it, after all this is only a plug not a head stud, and I like the idea of having anti-seize preventing any galling of the aluminum threads. Once aluminum galls you have a real mess and will become very familiar with a product called heli-coil.
08-14-2001, 04:14 PM
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Also, another practice is to put a drop of engine oil on the threads when installing the plugs as a simple "anti-seize" measure. While kind of low-tech, it has the obvious advantage of it not mattering if any gets in the cylinder! If you didn't put the plugs in yourself, this is another possibility you could consider.
-Mark 86 944 NA
-Mark 86 944 NA
08-14-2001, 05:29 PM
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I had a similiar problem with my 1987-944S,after looking into the spark plug holes with a flashlight I noticed that there was oil residue and there was a little bit of oil on the end of the spark plug connectors,it turned out to be the seals of the cam cover were leaking oil down into the spark plug cavity.When you remove the spark plugs the oil gets on the threads.Check this out.Hope it helps.
08-14-2001, 08:08 PM
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Thanks guys. I'm marginally more relieved now. However....after replacing the plugs, I checked them again. No oil on #2,3&4, but #1 still had a large amount of oil on the threads. I didn't apply any anti-seize myself, so it seems this wouldn't be it. By the way...are there torque numbers for the plugs? My normal practice is to tighten until I feel the washer squish. When I pulled #1 yesterday it still seemed looser than I'd expect though.
RFUERST944s...I like your answer best. I'll check that out. I don't remember there being a gasket for this area. How did you fix it?
RFUERST944s...I like your answer best. I'll check that out. I don't remember there being a gasket for this area. How did you fix it?
08-14-2001, 08:29 PM
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The way I fixed mine was to order from the Porsche dealer the cam cover gasket set,this has 1 gasket for the cam cover and 4 spark plug gaskets and the gaskets that go under the mounting bolts for the cover.You just remove the cam cover,clean up the gasket surfaces and put back together.Since I did this not 1 drop of oil near the spark plugs.
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08-14-2001, 10:06 PM
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gday - there is a specific torque for the plugs. I want to say 20 or 25 nM but don't quote me. I don't have any references with me. It's listed in the Haynes manual, as well as your owner's manual, if you have one.
The oil you are finding on Cylinder #1 may be left over residue. Did you stick a rag in each cylinder (thread) and wipe them all clean before re-installing the plugs?
The oil you are finding on Cylinder #1 may be left over residue. Did you stick a rag in each cylinder (thread) and wipe them all clean before re-installing the plugs?
