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oil in spark plug cavity?


Seanmannino

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:huh: Okay, so I have had a slight mis for a couple of days. Yesterday I swapped the spark plugs and wires and noticed that upon removal of Spark plug in cyl 6 there is oil around the threads. This is the only plug that has this issue. Car has around 106k on the clock and I am not sure what type/kind of abuse/mistreatment she had been through before I bought her back in August last year. from the Haynes book that I have it shows 6 spark plugs and there is one with oil on/around it and the information states that I could have a bad O ring or another type gasket failure. But wouldn't I have more than just the one plug is it was in fact a gasket or O ring failure? Any ideas?

Sean M.

1997 Cadillac DeVille

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Haynes shows 6 spark plugs? You have an 8 cylinder engine, there are 8 spark plugs, 4 on each bank

Oil can get into the spark plug ports via the seal. Besides the perimeter seal, the CAM covers have spark plug port seals, that if bad can leak oil into the ports

You might try snugging up your CAM cover bolts, DO NOT overtighten them just snug them up. At this age, those cam seals will crack up badly if you overtighten them, gentle snug

Eventually you need to replace the CAM seals, not a fun job

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Haynes shows 6 spark plugs? You have an 8 cylinder engine, there are 8 spark plugs, 4 on each bank

Oil can get into the spark plug ports via the seal. Besides the perimeter seal, the CAM covers have spark plug port seals, that if bad can leak oil into the ports

You might try snugging up your CAM cover bolts, DO NOT overtighten them just snug them up. At this age, those cam seals will crack up badly if you overtighten them, gentle snug

Eventually you need to replace the CAM seals, not a fun job

Nah it shows the 8 plugs for the actual car but shows 6 examples of plugs, One with the correct wear, one with carbon build up, one with oil around the threads, one that has been in an engine too long, and one that has been damaged. Basically the fouled plugs that can be pulled from a vehicle.

Sean M.

1997 Cadillac DeVille

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There is a seal for each spark plug cavity in the cam covers. The seals can seep a tiny bit of oil.

The labor involved with removing the cam covers to replace the seals is not worth it. The oil is usually harmless and simply gets baked on the plug; it looks worse than it is. And I doubt if the oil was the cause of your misfire.

Jim

Drive your car.

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There are round silicone o-rings that are between the cam cover and the spark plug well in the head. The o-ring on #6 is leaking. Not a difficult repair but you will need a power steering pulley puller to remove the water pump belt pulley off the cam. The seal around the cam behind the water pump drive pulley has three small screws. You need to apply sealant on the threads of those screws on reassembly since they are through holes in the cam cover.

If you're going to do this job, get a new cam cover gasket for the front bank and four spark plug well seals. You could also wipe out the oil from the plug well and see how long it takes to reappear.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Okay, I'll clean that up. Couple of questions, other than sticking a rag down there and hoping I get it all out what's the best way to clean it out? Also, I noticed this morning the misfire is back, not sure what/where to go from there, and I have a P0174 Bank 2 is lean code (no 02 codes yet :) so hopefully things are going in the right direction with this beast) Noticed when I pulled codes too that I now have DTC B2511 Steering Wheel Controls Conv Key Stuck. Last night while driving home I noticed that my wheel controls weren't working no worries I thought and went on about my business started the car up last night after dinner and they worked fine??? any ideas on this one?

Thank you all for your help! it really is appreciated (and keeps another caddy on the road!)

Sean M.

1997 Cadillac DeVille

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Just stick a rag down there and swish it around with a long screwdriver.

P0174 is indicating a vacuum leak somewhere on or near bank 2.

Okay, that's what I thought to do but wasn't too sure as I've never had this issue before.

I can hear the vacuum leak but I cannot find it anywhere! lol

One more thing, is it possible for a bad plug wire to cause a misfire, and also on really cold mornings could the bad wire in effect cause a hard start situation?

Thanks Ranger!

Edited by SeanMannino

Sean M.

1997 Cadillac DeVille

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One more thing, is it possible for a bad plug wire to cause a misfire, and also on really cold mornings could the bad wire in effect cause a hard start situation?

DEFINITELY can cause a misfire. Not so much a hard start.

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One more thing, is it possible for a bad plug wire to cause a misfire, and also on really cold mornings could the bad wire in effect cause a hard start situation?

DEFINITELY can cause a misfire. Not so much a hard start.

Perhaps you should check your fuel pressure in regard to the hard starting.

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Odd thing is, I haven't had a hard start since I swapped the plugs and wires. Tomorrow morning will be the true test though cause it's Snowing yet again in Denver and will be fairly cold. Hasn't been below I'd say 20 for the couple of days since I changed em sooooooo yeah will report tomorrow from work lol.

Sean M.

1997 Cadillac DeVille

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Well, it didn't get as cold as I thought it would this morning. About 23 when I went out to start the car. She started up first time no hesitation or anything. So I think I have gotten that all fixed up... and no more P0174 either I reset it the other day and have been driving around mostly to work and home but no Misfire, No Codes No CEL!!! WOOHOO lol NOW I just have to figure out which pulley is squealing and get that replaced (have a hunch it's the idler) but will get to that this weekend hopefully.

Thank again everyone for your valuable input!

Sean

Sean M.

1997 Cadillac DeVille

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