Uh oh! Possible head gasket?

[White75]

I was replacing the plugs and wires on my 78 L82 SA and all the plugs looked ok, old but OK, except for one, the #8 cylinder was a bit fouled with oily black residue (all the others were whiteish brown). the engine ran fine with no misfires but based on the coloration, something was up. I noticed more oil stainage from that bank of cylinders but I attributed that to a bad valvecover gasket that was replaced but never really cleaned up. However, I saw a bit of neon green fluid on part of the starter and that got me worried, especially since right above the fluid on the starter is the #8 cylinder.
Is this something that I can fix pretty easily in my very crowded garage or should I just bite the bullet and farm it out (how much estimated?). If I end up having to replace gaskets, is there anything I can do to raise the HP (raise compression?) or do a headswap that looks original on the outside?
Are there any how-to guides on the web on DIYing a head gasket?

 

[Hib Halverson]

If you have no signs of coolant in the oil or oil in the coolant and your compression or leakage test does not point at a head gasket, I wouldn't be too quick to pull the heads.

If you have evidence of coolant leakage on the outside of the engine near the starter I'd try and get a good look at the expansion plug in that area.

As for #8 being oil fouled...does engine use oil? If that fouling is just a "bit fouled" rather than truly oil fould and oil use is less than 3000 miles per qt, I wouldn't worry much.

On an L82, I wouldn't go much over 9.75:1 with an iron heads and 91 oct. gas. There are various ways to up the CR. You can mill the heads a little. You can go to a thinner head gasket. You can also switch heads.

 

[TimAT]

If it's an automatic, the TH350 or TH400 has a vacuum line that ports into the intake right about where #8 cylinder is. If the modulator starts going away, the trans oil gets pulled right into #8 and will make your plug look funny. Pull the vacuum line and see if there's oil in it.

Finding the source of the coolant might be tricky. Rent or borrow a pressure tester, fill the system and pump it up. Start looking. As Hib said, there's an expansion plug behind the starter- that could be leaking or it could be coming from between the head and block, or if the heads have been off, someone didn't get enough thread sealer on the lower outboard row of head bolts. Unfortunatly, the only correct way to fix that is pull the head and replace the gasket too.

R&R of the heads is not a real deal. Take the bolts out, clean everything, install new gaskets, put the bolts back in. Takes some time of you've never been there before, but everyone has to start somewhere. Plus you get the satisfaction of "I did it myself". And that's near priceless. There are a lot of guys on the forum that will be more than willing to help you out if you have questions.

 

[White75]

Thanks for the input. I'm going to try and clean the area good and let it run a bit to see if I can really pinpoint the leak. It's a manual trans but I'll definitely look at the expansion plug. I doubt the engine has ever been apart, I know it hasn't since 1982. I'll also do the compression test although I dread having to go after the plugs again.
The fouling wasnt too bad, just a thin coat of oily black but it was definitely different than the brown/white on the others.

 

[Tom Bryant]

I'll also do the compression test although I dread having to go after the plugs again.

I think Tim was talking about a coolant system pressure test. Check that modulator vacuum line for oil residue. I've had that happen too.

Tom