Oil on Spark Plug tip

[Deathacus]

Hey there! Was changing spark plugs, or rather, inspecting them all before I waste new ones, aaaannd the last one I pull has oil all over the tip. Absolutely soaked. Doesn't smell like gas, no apparent leaking from the tube seals. Couldn't tell ya about oil consumption since most of it is leaking out the cam seals. Engine runs pretty good although I did notice it ain't perfectly smooth at idle. Not bad tho. Just made from Pitt to Milwaukee and back a couple weeks ago.
So like, where is a good place to start? What do I check?
I hope it's not related but it looks like I'm getting oil in my coolant again, even tho none of my testing indicated any problems. Not that I completely trust my methods, so if anyone is more experienced than my with this motor, lemme know!

Also, anyone who dreads doing the rear plugs, don't worry. '94 MTX at least, just pull the plastic trim above the wiper motor, and the can and valve for the butterfly actuators. No need to pull the intake.

 

[BaySHO Performance]

If no leaking tube seal, worn compression rings? I suggest doing a compression and leak down test. No blown catalytic converter, right?

 

[Deathacus]

All tube seals are bone dry. Compression test shows 190 after 5 cranks, 220 after 11 cranks. Although I'm not sure how accurate my gauge is but all the cylinders seem pretty consistent.
Leak down shows only 0.5% @ 100psi, but I can hear a little air through the oil dipstick tube. No bubbles in the coolant.
I double checked the plug and realized the platinum disc on the ground strap was missing. That might have happened while I was cleaning it tho. I regaped the plug, warmed up the engine to do the testing, ran about the same as the other day. Still came back out oily. How would I go about testing the cats?

 

[BaySHO Performance]

The purpose of checking the cats is to make sure nothing got sucked back into the engine, scoring the cylinders. Could happen if the front half of a cat is blown. That could have happened if you ever heard the engine backfire.

How to check cats for damage, and the consequences

Take the Y pipe off. Check each end of the cat: the material is in two halves and often only one half has disintegrated. Stick something flexible and long enough to reach the cat material and see where it stops. I use a flexible pickup tool. Should be right where the cat gets to the widest point. Or even tap both ends on the ground to see if any black sand comes out, or use a bore scope.

This is what will happen if one of the halves has disintegrated:

Back half: Cat material will now be in the exhaust behind the Y pipe. Some may have even finished up in the mufflers. If they are stock mufflers that have three pipes in them that double back on each other it will be impossible to remove the material. Definitely has happened if they rattle when you bang on them. Not too big of a problem as long as they can still flow freely. Only recourse is to change them. Doesn't happen with aftermarket mufflers that only have a single pipe from front to back.

A large chunk can also get stuck between the Y pipe and mufflers creating huge back pressure and a significant loss of power. A drain snake may be able to break it up. If not, use the drain snake to find out where the blockage is, mark that spot and take it to a muffler shop to have them cut it open at that point to remove the material.

Front half: Material usually gets sucked back into the engine, scoring the cylinder walls beyond repair. Use a bore scope to see if you can see vertical scratches on the walls. If the scratches are faint and at an angle, that's the normal factory cross hatching:

 

[Deathacus]

Well, my Harbor Freight bore scope is pretty much useless. I can really only see the tops of the pistons and its super dark and grainy. I wonder if I can rent such a thing.
As for the cat, It's a replacement put on by the previous owner, so if such a thing had happened before that, I wouldn't know.

Update: tried the horoscope again and got this
Is this bad?

Also did a leakdown test thru the dipstick and it held no pressure at all. I could hear air near that cylinder but wasn't sure if it was a weird internal pcv or something

 

[Deathacus]

Finally got around to pulling the y-pipe. Looks practically new. No missing chunks or anything.

 

[rubydist]

Have the valve stem seals ever been replaced? I have taken apart some of these engines where the exhaust valve stem seals were totally trashed, yet the engine only used a moderate amount of oil - but in that scenario you can get oil on the plugs.

 

[Deathacus]

That makes sense. Any way to test such a theory before throwing parts at it?

 

[BaySHO Performance]

That makes sense. Any way to test such a theory before throwing parts at it?

Good question. I don't have a definitive answer. You mentioned that you heard a hiss of air in the dipstick tube during a leak down test. I wonder if you could more closely pinpoint the hiss? You might be able to do that with the intake off. I use a mechanics stethoscope with the rod removed to pinpoint hisses. If you find a leaking valve stem seal, might as well replace them all. Available from Rock Auto.

 

[Deathacus]

Reading a few other threads and had my mum help with one more test before pulling the intake. At start, just one quixk, light puff of blue smoke coming out where the muffler used to be. Didn't let it warm up for very long but on acceleration it sharted this stuff all over my arm and flashlight. Rude. Was wet but dried like water, didn't seem oily. I've noticed spots like this on the driveway before. Uppon sudden release of the throttle, no smoke. Seems that indicates towards valve stems and not rings, right? But what about this crap? Also lost about half an inch of coolant from the reservoir over about 1000 miles, hard to say if there is still a leak or air purging itself since the water pump change.

Okay, now I'm confused. I just pulled the plug and it's clean. Looks a smidgen hot but pretty clean, and dry. I took a Sheetz run last night for some soda, clean. let her idle for 5 minutes today, clean. What they hay?

 

[Deathacus]

Welp, pulled the valve covers anyways since she was due for a valve shim job and a few leaky seals. I'll buy the valve stem seals since they're cheap enough and I algready gotta pay shipping. I'll decide im the mean time if I actually use them.

As for the valve cover bolts, are they supposed to be the same on both heads? The two small bolts on my rear head are just plain rusty caps screws, same 5mm allen. Hard to find a photo of a stock 1994 that shows those off.

 

[BaySHO Performance]

Bolts are the same for both heads. The chrome on the small bolts is not good, and any spares you find will probably look the same.

 

[Deathacus]

Anypony here install Viton valve stem seals? SHO source website says intake and exhaust oughta be the same, yet the set I got has two different ones. I emailed him, no answer yet. Afraid of popping the old ones out to compare incase they just fall apart. That, and I don't understand how they can be the same if the stock ones are different for in and ex.

 

[BaySHO Performance]

Anypony here install Viton valve stem seals? SHO source website says intake and exhaust oughta be the same, yet the set I got has two different ones. I emailed him, no answer yet. Afraid of popping the old ones out to compare incase they just fall apart. That, and I don't understand how they can be the same if the stock ones are different for in and ex.

I do know that the intake and exhaust seals are of a different color as SHO Source says, but don't think there are any other differences. Haven't used the Vitons which are supposed to be superior according to SHO Source.

 

[Deathacus]

One is just a little taller than the other. Got a chance to peruse RA between customers (literally the only time my brain can focus for some reason). It looks like the taller one with the rubber extending onto the shoulder (the one to the right in my photo) is the intake.

Hopefully I can get it and the cam seal done in the next two weeks so dad can lay new gravel in the driveway (just for me to leak my steering all over it)

 

[Sho-N-Go]

Did you get the valve stem seals changed?

 

[BaySHO Performance]

FYI: make your own valve spring compressor:

Valve Spring Compressor - V6SHO

wiki.wikisho.com

 

[Deathacus]

Just now getting around to it. Question: I'm using compressed air thru the spark plug hole to keep the valves closed, and I see just a teeny bit of oil bubbling around the stem after pulling the seal. Is that normal, or is my valve not sealing right? Using my leak-down tester for the air and it's only showing a 2% leak.

 

[BaySHO Performance]

Just now getting around to it. Question: I'm using compressed air thru the spark plug hole to keep the valves closed, and I see just a teeny bit of oil bubbling around the stem after pulling the seal. Is that normal, or is my valve not sealing right? Using my leak-down tester for the air and it's only showing a 2% leak.

There's obviously blow-by on that valve, but that may be because the compressor isn't keeping it fully closed. My guess is that the oil came from the valve stem rather than inside the cylinder.

 

[Deathacus]

Oh yeah, just stagnant oil sitting in the well. Just wondering if there is supposed to be any blow by. The compressor is only pushing ~100lbs into the cylinder.