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2002 Cadillac DeVille DTS
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Discussion Starter #1
577995

So other threads I've seen describe "a little oil in the spark plug well" as "normal" or to be expected at 100k. It's at 121k, bought it maybe 5k mi ago in the span of 3 years? I figured it'd been done by now, but when it started getting rough I checked plugs and they're done. So I did the rears, maybe A drop of dried oil in some, but 2 with threads that looked like they'd seen oil from underneath. This plug was drenched in oil from the front. I didn't notice much of anything from the top in any of them, so maybe there's just THAT much under there? So my question is this "100k normal" or is this something I need to fix and what do I need to do or rough book time repair? I feel like this is a bit much to be normal. Thanks guys
 

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2001 eldorado,2008 DTS,2005 XLR, '96 eldo,'95 eldo,' 89 eldo,'78 eldo,'11CTS-V
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Yea, that's a bit much. The silicone seal in the camcover has failed.
...or the camcover is loose.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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67,924 Posts
Yep - as posted, a bit of oil in the plug wells and on the metal plug shell is normal, but that one is a bit much.

At least it's a left (front) bank plug so you can put it all back together and check again in a year or two. Don't go crazy tightening the cam cover bolts - very little torque required.

89 lb/in or about 7.5 lb/ft.

Cam cover seal replacement is about 4 hours labor and $500 in parts at a dealership - almost $1,000 total. Oil is cheaper. Remember - the water pump drive system must be removed from the left bank intake cam snout - touchy work, correct tools. The AIR check valve must be removed from the right bank cam cover. A bitch of a job.
 

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2002 Cadillac DeVille DTS
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29 Posts
Discussion Starter #4
So...again, is this something I SHOULD fix? Will it hurt it to not fix it?

I already put oil in it because of the oilpan silicone gasket, so not too worried there, and I have a mechanic friend who only charges $40/hr labor, but I don't like to abuse that privilege unless it really needs doing
 

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White Diamond '03 DHS (with DTS floor shift)
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It took 18 years and 121,000 mile to get where it is. It would be a lot cheaper (and easier) to check it once every year or two or three and clean it out. Just something to consider.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Yep ^ ^ ^ - clean the plug wells and boots, put it all back together and check in two or three years.

........ and the spark plug socket artificially makes it look like there's more oil in that well than there actually is - sort of like sticking your fist into a partially filled glass of water.

Was that plug boot tip oil soaked ?
 

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2002 Cadillac DeVille DTS
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29 Posts
Discussion Starter #7
The boot was fine, the tops of all plugs all dry, but the electrode tip must have been dunked in oil. So I can stick a rag deep down in where the electrode sits and dry it out and it'll be fine to drive even with oil accumulating/bathing in it without causing damage?

Obviously that plug was the worst so far, and I'm cool buying a new plug every year or two if needed, so long as it doesn't hurt anything else. I've never seen or heard of a setup like this before, coil cassettes is unique
 

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2002 Deville and 2009 DTS
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I changed the sparkplugs on my 2002. Oil ran down into the cylinders.
BOY did smoke pour out the muffler for about 5 seconds when I first started up the car!

You should be fine. The oil was an accumulation over the years ( most likely the last 5-10 years). So you should be good for another 5 years...
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Oil is an insulator - no problems there. The electrode tips got wet with oil as you pulled the plugs - think about it. (If the tips were wet in the cylinder then the plug was not fully screwed in ........... or you have massive oil control ring problems.)

Properly exercised and driven HARD on occasion your engine should get between 1500 - 7000 miles per quart of 5W-30 oil. I get over 6500 - rural, highway, yeeehhaaaa!!!!!.
 

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2002 Cadillac DeVille DTS
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Discussion Starter #11
So hopefully last question: got them all installed, scuffed and cleaned up all the metal tower bits on the coil cassettes things or whatever their proper name is, cleaned every boot meticulously, put back together, rougher idle than ever, cylinder 2 still misfiring but cylinder 6 code was gone. Had to drive it home, cleared all codes, rough idle while stopped, flashing engine light at heavy acceleration SOMETIMES, steady engine light for half a minute here and there, mostly off entirely. Is this because maybe some oil got in the cylinder like stated above or do I need to replace a coil cassette or what's going on? No other codes than evap purge solenoid, but that wouldn't do anything
 

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If you put in new sparkplugs and cleaned everything else. I would suspect:
1) the boot on cylinder 2 might be bad
2) the "tower" or connection on the Ignition coil pack on cylinder 2 is bad. ( this is the part that slides into the boot when you install the coil pack).
3) did you put in the boots BEFORE you installed the coil pack? This is what you are supposed to do. I have heard some people put the boots on the coil pack, then install. ( this is wrong).
4) it is possible your "even number coil pack" is bad. Even though 4,6,8 are firing, the wire to #2 could be open.
 

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2002 Cadillac DeVille DTS
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Discussion Starter #13
If you put in new sparkplugs and cleaned everything else. I would suspect:
1) the boot on cylinder 2 might be bad
2) the "tower" or connection on the Ignition coil pack on cylinder 2 is bad. ( this is the part that slides into the boot when you install the coil pack).
3) did you put in the boots BEFORE you installed the coil pack? This is what you are supposed to do. I have heard some people put the boots on the coil pack, then install. ( this is wrong).
4) it is possible your "even number coil pack" is bad. Even though 4,6,8 are firing, the wire to #2 could be open.
Yes, I greased up the outside of the top part and the openings just a smidge with dielectric grease and stuck them all in first so I knew they'd seal. How would one test the boot and the coils with a multimeter? I'm still kind of new to that stuff
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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A bit of oil in a cylinder will burn off quickly. As Rob said, it's a problem with the cassette itself, plug, boot, or maybe the (removable) ICM-to-cassette connector.

If any of the 4 coil tips and nearby plastic/epoxy casing is cracked the cassette is no good. Junkyard, gray or black, both cassettes identical except for color.

coil-boot-plug 1.JPG
2011-07-09_100054_carbon_tracking.jpg
Spark plug boot and spring.JPG
 

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2001 eldorado,2008 DTS,2005 XLR, '96 eldo,'95 eldo,' 89 eldo,'78 eldo,'11CTS-V
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Swap cassettes. See if the miss moves. Both cassettes are the same.
 
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