M1917

We're at the end of January and it's not even the mid point of winter in Western Pa. But, I'm thinking of spring. I have a bunch of projects to get done on the Corvette before the weather clears. One of which is a good old fashioned tune up. Cap, rotor, wires..... Frankly, it's the plugs that has me concerned. The car is a 90 and has 65K on the clock. The plugs are old. As in there is some surface rust old. I'm half afraid of attempting the project as simple as it should be. I was going to spray some penetrating oil in there a few weekends ahead of time. Has anyone tackled a similar job? Any tips for removing old plugs? I'm terrified of breaking one off in the head.

pipe

It wouldn’t hurt to spray a little on em Also run the motor a bit and change em while they’re still warm When ya put the new ones back in put a dab of Anti Seize on em then the next time ya go to take em out it will be easy

Beater12

If that's aluminum heads I was under the impression you want to take them out cold to avoid risk of turning out the threads. Please correct me if I'm wrong.

65Z01

The '90 heads are indeed Al, I always do the plugs cold.

The left side will take ~15min, the right side will take >1hr including all the cursing involved...

Natty C

Depends on how much they were torqued last time they were changed. And if anti-sieze was used. But surely they can't be the original plugs and the car only has 65,000 miles on it, so it's highly doubtful they'll be fused to the aluminum or anything, even if anti-sieze wasn't used last time they were changed.

I like to go a little lower than the factory torque on those aluminum heads. And definitely apply some anti-sieze to the threads.

I did the plugs on my '90 when I bought it.

The #2 plug was the pain in the rear end.

I managed to get it swapped out without having to remove anything, though.

It took about an hour and a half/two hours, if I recall correctly. Something like that. Think it took around 45 minutes to get the #2 plug swapped. That took the most time getting to.

I dunno how old the plugs I took out were, though, because I'd just bought the car at the time.

Here's what the old ones looked like...(clearly whoever installed them prevously didn't put dielectric grease on the ceramic where it's actually supposed to go)

jrobin1

Here's what the old ones looked like...(clearly whoever installed them prevously didn't put dielectric grease on the ceramic where it's actually supposed to go)

NattyC, can you explain to an amateur why the dielectric grease goes on the ceramic?

Phobos84

I have a small side business were I pull apart engines and sell hard to find parts on ebay. One thing I sell a lot of are aluminum heads. Mostly LS 243/799 heads pulled from Chevy trucks. Of all the heads I've pulled, I only once had one head that had the threads damaged from an old rusted plug. I was able to repair it and still sell the head. If I were you I would do this job now being your (like me) in western PA (I'm near Clarion) and it's freaking cold out. I would spray each plug with PB Blast the day before. Use a 6 point deep well socket and a fine tooth ratchet. Nice even pressure until the plug turns. Even if a thread or two where damaged the plug threads can be repaired with a tap. If your close to me I could lend you one if you need.

Worst case if you completely destroy the threads you'll have to pull the head and use a heli coil. Yes it's a pain but not the end of the world.

Natty C

Well, that was just my amateur opinion. Heh heh.

Dielectric grease is not conductive. It's just an insulator. So I just put a little there where the boot meets the ceramic and a little on the ceramic.

I don't use dielectric on the plug terminal itself. I'm of the view that it interferes with the current creating the possibility of misfires.

Of course, opions vary. Others may certainly disagree.

jrobin1

OK, I get it now. It's to keep the boot from sticking, huh? I thought I was missing something on making the plugs easier to remove. Ha

93torchy

RE dielectric grease. It also helps the boots come off easier the next time around. No?

Natty C

Well, yeah, I guess it does make them easier to remove. I've never had one get stuck myself, though. But it also opens the possibility of misfire.

I just put it on the boot where the ceramic meets to keep moisture out and keep it from arcing onto the ceramic.

pipe

The Dielectric grease is put on the ceramic part of the plug to stop the plug wire boot from sticking to it after time If it wasn’t on there and you tried to pull the plug wire off the metal connector on the end of your plug wire would be on the end of the plug and you would be holding just the wire and boot with no connector

Natty C

Hm. That makes perfect sense. I wonder if that's what the old man meant when he mentioned about greasing the ceramic and I just wasn't paying good enough attention. Seems like I've been doing it right all of these years, but for the wrong reason.

84 4+3

Even in boats in Salt water... maybe a hand full have ended up with an issue vs the thousands I've seen dad do... do it cold, use a good socket, use a good ratchet with a long handle. If the end of the plug does break off tap in an easy out... I've only had to do that once personally on an 03 dodge 1500 with the magnum V6... and those were in there for 115k and every NJ winter... the factory plugs.