Corvette Forum : DigitalCorvettes.com Corvette Forums banner

1 - 13 of 13 Posts

·
Registered
Joined
·
386 Posts
Discussion Starter #1
Hey there, i bought a car that has been in someones family for 15 years, 86 vette, it has 96k miles on it, and it would sit for months sometimes year at a time, anyways i pulled the old spark plugs out and noticed black deposits on the ends of the plugs and oil around the threads in the block. It had leaking valve covers on both sides, both were realllly shot, all 8 plugs had the black oily looking liquid on the threads. anyways i changed them out, forgot to clean the oil from the cavities and put the new plugs in, ran it for about 15 minutes yesterday and it sounded fine other than some rocker noise and the hole in the egr tube. decided to pull a plug out today to see what they look like, it had oil on the threads (because i forgot to clean the cavities out) but no oil on the electrode or anything like that... i am hoping the rings aren't screwed or the valve guide seals. what should i do to check for these problems? can a car sitting for long periods of time eventually get oil on the spark plugs? did not notice any blue smoke when it was running. what should the oil pressure read on the dash gauge? keep in mind that both Valve cover gaskets were shot, and there is oil and sludge on both sides of the block around the plugs. I just could not imagine the oil climbing up the threads?
 

·
DC Crew
Joined
·
32,974 Posts
Yea it could be from the leak. If your valve guides are bad you will get a puff of smoke on start up, if your rings are bad you will get smoke most anytime depending on how bad they are. You can run a compression check to see if you have any ring issues.
 

·
DC Crew
Joined
·
20,699 Posts
^^^ What raid said.

I know when I bought my '85 it needed v/cover gaskets bad because it was low miles and only driven occasionally. Over time the oil had leaked down by the plugs. Easy to clean up though, some will burn off but the rest will have already collected dirt and will need attn from some degreaser and old rags.
 

·
Registered
Joined
·
3,516 Posts
You can do a leak down test

But, I'd clean it out

Put the new plugs back in a run it for a while

Clean the oil off the side of the block
(Bad Valve cover gaskets)
 

·
Registered
Joined
·
386 Posts
Discussion Starter #5 (Edited)
:huh: Cleaned the plugs, cleaned the cavities, put the plugs back in, ran it for 5 mins, let it cool down, pulled a plug and the electrode was wet, and the black liquid once again on the threads... the liquid on the electrode looked clearish brownish if that makes any sense, has a faint smell of gas or oil mix, but when you wipe your finger on the threads its black liquid.. Valve covers are not leaking , put new felpros on there (keep in mind im still in the process of gettin her idled and running. No smoke from the exhaust and the area smells heavily of gas when the car is running and the exhaust fumes burn the eyes (not safe at all!) but its probably burning off all of the old crap that's been sitting around for a long time. i guess ill have to do a compression test to see :lookinup: I am hoping its just excess fuel, because id rather chase down that demon than have to look for another motor.
 

·
Registered
Joined
·
476 Posts
Sounds like you may be running a tad rich. and that black liquid could be fuel that has been made dirty creeping up the threads.... you thought about putting a lighter to it to see if the questionable liquid catches?
 

·
Registered
Joined
·
181 Posts
What you need to do is drive the car & keep track of you oil level, checking your plugs after only running it for 5 minutes doesn't tell you much.
 

·
Registered
Joined
·
386 Posts
Discussion Starter #8
ya i need to get her running properly before i take her out, its just crazy that they got wet after 5 mins of running though? They should never be wet in the first place, I am really hoping its fuel, ill find out this week. Thanks for the IAC TPS help guys!
 

·
Registered
Joined
·
9 Posts
Hi,
This car has a cold start injector. Are you getting any codes? If no codes,
unbolt the CSI & turn the igniton to the on postion, (for fule pressure)
if the CSI leaks then you've found what could be your problem.
Rich
 

·
Registered
Joined
·
386 Posts
Discussion Starter #10
could the CSI have anything to do with all 8 plugs being fouled? i am also leaning towards valve seals.. the car doesnt smoke at all though.. i just need to drive it to see if it smokes under heavy load, or just on deceleration..
 

·
Registered
Joined
·
386 Posts
Discussion Starter #11
also, how much oil should there be under the valve covers? the seller claimed he hadn't driven the car for 6 months, I wont take his word for it but anyways when i towed it home, i did the valve cover gaskets, and there was a lot of oil around the head, dunno if I am explaining it right, but normally when I see valve covers off, it looks wet around the valves, but not puddles of oil. I read this post by someone on another forum and I hope he is right

"I have yet to see bad rings on a car causing it to burn oil since 1975. Oil at start up and no other time is usually valve seals. One thing I do see a lot of is cars that are not driven enough. The drain hole in the back of the heads gets clogged with sludge and the oil puddles back there so much that it overwhelms the rear valve seals. If you take off your valve cover, don't be surprised to see a bunch of oil come running out.

BTW the only causes of burning oil I've seen from experience are seals, head gasket or intake gasket. Rings could do it but I've yet to see it. I have seen bad top rings due to piston damage from Nitrous but that's it."
 

·
Super Moderator
Joined
·
8,498 Posts
post CLEAR pictures of all the spark plugs and we can tell a great deal more about the potential source of your problem
 

·
Registered
Joined
·
9 Posts
Hi,
What you read about the sludge build up from not running the engine long enough is correct. Oil has waxes & tars in it plus whatever it picks up from the combustion process. For the oil to be able to lift & keep this mix in suspension it needs to be hot, so it can be deposited in the filter or drain pan. Oil doesn't carry heat off as well as water, so it takes about twice as long to get the oil up to operating tempture then it does for the water, people see the water temp guage reading normal after about 13 mins. & shut the engine down. Now the oil is just warm enough to have started moving the waxes & other crap, bam it's shut down, no more circulating so it hardens back up only now it has some buddies hanging with it at a place where it can keep building, thus the oil puddles. If a person only wants to run the engine instead of going for a cruse, they need to run it at least a half hour. It should really be driven, there are things that need the vehicle moving to lubricate. IE differental for one.
Get yourself an engine brush & put it down the oil drain back holes in the head, drain the oil change the filter & refull it with pure synthetic, there are no waxes or tars in pure synthetic
(pure synthetics. Delvac-1, AMSOil, Redline, and Motul 5100)
Semi-synthetics are oils which are a blend of petroleum oil and no more than 30% synthetic oil.
Good luck,
Rich
PS That black wet stuff your wipening off the plug threads is a mix of gas & carbon, you need to do what was mentioned above & then go for a long ride, buzz around town do some interstate then go home & check things out, it wouldn't hurt to put something like seafoam & dry gas in the fuel tank as well.
 
1 - 13 of 13 Posts
Top