Why do my spark plugs have tumors on them?

Topic: Why do my spark plugs have tumors on them? (Read 4621 times) previous topic - next topic

Why do my spark plugs have tumors on them?

September 06, 2005, 11:23:56 AM

For the last 30,000 miles or so (4+ years), I've had to replace the spark plugs on the passenger side bank of my '85 3.8L Cougar every 10k miles or so. See below...

I've had it suggested that it is due to the head gasket. Das Cougar doesn't have any of the normal signs of a head gasket leak. No coolant in the oil, oil in the coolant, bubbling coolant, white exhaust smoke, etc. The only symptom is a slow loss of coolant, which I chalk up to a leak on the rear of the lower manifold. What do you guys think?

Re: Why do my spark plugs have tumors on them?

Reply #1 – September 06, 2005, 12:47:32 PM

here you go

http://www.autolite.com/tech/PlugTips.pdf

Re: Why do my spark plugs have tumors on them?

Reply #2 – September 06, 2005, 12:52:14 PM

looks like ash or oil fouled. Sounds like you have been adding something to your gas?

Re: Why do my spark plugs have tumors on them?

Reply #3 – September 06, 2005, 01:26:02 PM

:hick: stop using leaded fuel...

Re: Why do my spark plugs have tumors on them?

Reply #4 – September 06, 2005, 01:38:03 PM

Thanks for the pdf. I did a google search, but couldn't find a picture illustrating ash deposits so well. The car gets Shell 87 octane all the time, so it isn't an additive/leaded issue.

So, how do I fix this? Valve seals, valve guide replacement, piston rings?

Re: Why do my spark plugs have tumors on them?

Reply #5 – September 06, 2005, 02:07:31 PM

Jeremy, do gas stations in your area have an ethanol or other fuel mix (reformulated)? I know there are different blends for different parts of the country. That could explain it....

Re: Why do my spark plugs have tumors on them?

Reply #6 – September 06, 2005, 02:33:21 PM

No, I don't believe Alabama has any of the special formulations of gas because there isn't much in the way of emissions requirements here. My '87 3.8 uses the same gas and doesn't have this problem. Also, it only occurs only on one bank...wouldn't that eliminate the possibility of gas/oil additives?.

Re: Why do my spark plugs have tumors on them?

Reply #7 – September 06, 2005, 07:47:02 PM

You need valve seals. I had the same thing happen in my old '85 3.8. You can replace 'em with the head on the car but it's tricky, so get yourself a shop manual

Re: Why do my spark plugs have tumors on them?

Reply #8 – September 06, 2005, 10:45:16 PM

I've been meaning to replace the valve seals for a few years. I guess they go to the top of the "to do" list. Hopefully my brother doesn't total the car before I get it back.

Re: Why do my spark plugs have tumors on them?

Reply #9 – September 06, 2005, 11:38:37 PM

I agre with Carmen... Definatly a classic case of bad valve stem seals, or maybe blocked drain back passeges in the ends of the heads. So how many quarts are you using per mile???

Re: Why do my spark plugs have tumors on them?

Reply #10 – September 06, 2005, 11:55:44 PM

Good question. Before I had the rear main replaced, I think it lost a quart every 500 miles. I didn't drive it much, so there'd be weeks between when I had to add oil. The rear main started leaking a day after it was replaced, I suspect due to the excessive blow-by.

On edit: It could have been as low as 1qt/300 mi. Hey, oil is cheap.