Any ideas on whats wrong?

 

Valve stem seals or years of low speed driving. How many miles on the plugs? What did the other plugs look like? (photo?)
Any work done to the heads?

 

First guess would be valve seals. You could try putting a hotter plug in that hole or just replace the valve seals first.

 

Just one like that or all 8?

Does the engine smoke on startup, while running, etc?

If you pull the PCV valve while running is it chugging hard out the valve cover hole indicating excessive blow-by past the rings?

Is the timing set correctly?

That definitely looks like bad oil/carbon fouling- gotta do a little detective work to figure out where it's coming from.

 

Looks like ash deposits from oil additives that are being burned. Is it only one cylinder? If so, make sure it's not brake fluid or tranny fluid coming in thru a vacuum port.

 

The plugs have about 10k on them. The rest looked ok for the most part. Car has 125k on it and as far as I know it has never been apart. Last owner had it since 97 and 20k miles and I have all receipts for any work done. I've had the car for about 8 months and I really don't get on it as it pings with the timing set at 6 degrees. I use premium fuel always too. Thought that wasn't normal.

Valve seals huh? The car never smokes upon startup so I would assume that was seals. Car does use some oil....about a quart in 2500 miles. The hotter plug is what someone else suggested. I just pullled out NGK's and a set of Autolite AP 42's went in because they came with the car. Will go with a hotter plug next time around.

Just one cylinder.....the rest looked ok. Not perfect, but not like that.

No smoking ever......does have some blowby from the PVC but not what I would say is excessive.

Timing is at 6 degrees.


Doesn't seem to be using any other fluids, but I'll check that out too.

Thanks for the input guys!

 

On my pickup truck, I was changing plugs on one side about every 6 months because they always fouled up. That was only about 3000 miles worth of driving. I changed all the valves seals. I haven't had a plug foul up since and the engine now uses no oil between oil changes.

Using a hotter plug is a bandaid repair for something else that's wrong.

 

I agree completely......and I have replaced enough things already that a set of seals shouldn't be a problem. Anyone have suggestions on the best type to use?

 

My truck uses the factory style square o-ring. Umbrella seals on the intake valves work fine.

My race car doesn't use any because of the limited access with triple valve springs but I'm also not concerned with oil consumption since it's not a high mileage vehicle.

 

If only one of them is bad then you've got some kind of issue with that cylinder. I'd do a compression test on all 8- just to see if that cylinder is noticably lower than the others. I'd also try replacing the plug wire to that cylinder as well, just in case you've got one flaky wire.

 

I think Damon is onto something. I would suspect a cracked ring or something.

- compression test
- night time - check the plug wire to see if it's arcing?

How does it run now?

 

I'm going to get a set of the o ring/umbrella seals and try that first before I go real deep. Any particular brand to buy? Do they make them in viton?

I'll do the compression test this week hopefully and a leak down test if I get the equipment. None of the plugs were great, but this one was noticably worse than the others.

I did put new wires on when I did the plug, but can check again to be sure.

At night I don't see any arcing and the car runs perfect now.

 

Did you check plug heat range? Right plugs for car ? Personly I have never had a chev want to run on anything but AC s

 

Brining this one back from the dead....

Finally doing the valve seals tomorrow.....over a year later, LOL. No other issues other than the fouled plug.

Did a compression test a few months ago on the one side with the issue and they were all equal, about 170 PSI IIRC.

Forgot to open the throttle body though, but I thought it was good they were all equal.

We'll see if it uses any oil once the seals are replaced.

New wires and Bosch Platinum plugs going in too.

 

If the car has been sitting for a year, squirt a little wd40, 3 in 1, pb blaster, or oil down the plug hole to lube or break free the rings. There is a fitting that you can screw into the plug hole to use an air compressor to keep the valve up when you are putting in new seals.

 

Thanks for the tips, but what I meant is that it has been a year since I wanted to change them. Car has 138k on it now!

Got the fitting for the spark plug hole too....worked great when I did this on my last IROC.

 

Interesting day to say the least......

Removed the passenger side valve cover, which was the easiest of the two and the side where the problem cylinder was. Engine looked clean inside without a hint of sludge. Thought it was pretty nice for all the miles on it.

First thing I noticed was the valve cover gasket had a section cut out, why I don't know as it didn't interfere with anything and it was leaking oil slightly. Maybe a shady mechanics trick? The new gasket took care of that.

I took the spring off the exhaust side first. It did have the same style seals on it, but the O rings crumbled and the plastic was discolored from heat/oil. Not sure if these were factory seals or not, but I have records back to 22k and didn't see where they were replaced/added. I pulled the old ones off, cleaned the valve/guide and reinstalled the spring. Twisted the pushrod around before reinstalling the rocker to make sure it was seated in the lifter and it didn't feel right. Pulled it out and it was bent pretty good, enough to be rubbing the side of the head. At that point I pulled the spring back off to see if anything was glaringly wrong. There was a little movement in the guide, but nothing that I would call excessive. Everything else looked good.

Pulled the rest of them down and only had the one bad pushrod. Replaced both of them on that cylinder and buttoned everything back up. Car starts and runs with no issues. Had a funny idle occasionally, but nothing else. Being bent I would have expected to have seen more truthfully. Haven't driven it enough to know if thats gone, but the car does seem to run better.

Only did the one head.......can't wait to see what happens with the passenger side.

Any thoughts?

 

Aw, Comon! stop toying with us!
Do the other side already!

 

Actually, the other side should be uneventful......all the plugs look pretty good on that side. Some of the pollution stuff has to come of just to get to the valve cover.

Who designs these things?

 

Just a small update.....I never did the other side...figured I'd wait for better weather since I didn't see anything glaringly wrong on the passenger side.

I inspected the plugs the other day on the driver side. All look even now......it apppears that the pushrod was the issue all along.

Took the car to the track late in the season last year and it ran a 14.45 so it looks like everything is where it should be.