I have been trying for a week to get the #8 plug thread to start on 92 coupe with no luck and I've about had it. I can't get the evaporator cowling out to gain access to that plug without dropping the catalytic converter, but how do you get to the bolt to exhaust manifold above the exhaust pipe loosened when there is no way to get a socket on it??? Did they purposely design this car to be as close to unserviceable as humanly possible?

 

Is #8 the rear most driver's side plug? I can never remember...

Anyway, if you're needing to get in there, it's a lot simpler to jack the car up, pull the front wheels and remove the rear portion of the splash shields (inner fender shells). Then, with the help of some long wobble extensions, you should be able to get right in there.

 

The only way I've been able to completely tighten and loosen that last header bolt is with a small 1/4" drive Craftsman ratchet with the short 1/4" drive flex joint and short socket. You need small hands though. Even like this it's still a PITA. I sometimes need to use a magnetic wand to guide the socket end onto the nut for me, cause it moves on you with a flex joint.

 

I don't see in your profile where you live at. Someone might be kind enough to start a mod party at your place and then you will get your plug installed....

It is a pita but doable. I am skinny and I can barely get my hand in there to get it started and I usually loose alitle skin in the process.

I agree with eschoendorff, wobble extension help.

 

You can get to the manifold bolt from the bottom with a small wrench, or from the top with an offset obstruction wrench.

Do you have the stock exhaust manifolds, or headers? I have changed the plugs with both and never had a problem on my L98, but I guess a LT1 could be different.

Good luck in your endeavors.

 

This car has 115K on it and the bolts off the lower end of the stock manifold are covered with rust, and no doubt frozen tight. No way I'm going to get one of them off with anything small enough to fit in the availible space.

I did manage to get one of the two evaportor housing bolts that was blocked by the catalytic converter off yesterday with an offset ratchet, and the last could be drilled out of the firewall from inside the vehical, so I'll probably try that when I'm in a better mood, like in another week or so. I'm still not sure I can even get that plastic evaporator housing out of the way even after the last bolt is removed so I'm in a pretty dark mood, nearly ready to set the car on fire.

I'm not huge, 6'1" 200lbs, but no way I can get my hand into that space at # 8 plug no matter how I try. I'm in Colorado Springs and the local dealer isn't an option. They told me awhile back when I had a much more minor problem that they opened in 98 or 99 and didn't have any experiance with older Corvettes.

 

I had to do just what you are doing last summer.

the manifold is a pill, eh? but those bolts are not that tight! I was stunned... so much so, that the last bolt was GONE. No kidding on that one.

What I have found is if you turn your back to the car and reach in that way. it buys quite a bit of room.

As for #8 plug, put the plug into a plug socket, with the rubber insert to hold it secure, then hand start it, and finish it with a 3/4" off set box wrench. That will fit the machined nut end of the plug socket.

I have done this enough now that I can do all 8 plugs in about an hour.

 

If I could hand start it, I would have had this job done a week ago. I can't get the thread to catch.

 

I've got hands like hams (I wear a size 16 ring) so if I ever need to do any close/tight work, I just bite the bullet, and have it done.

 

Its not that bad bro. I find it easier to come up from the bottom side and thread that way. As for the evaportor housing, dont bother, its not gonna move. Pullin the manifold was easy, that #8 bolt was so loose it came out by hand (not good). As far as getting it back in thats a pita. be patient, or youll end up liuke me with the motor out doing a full on rebuild because you got impatient.

 

I was afraid that evap housing wasn't going to come out. Thanks for saving me the trouble of finding out the hard way. No way I can get my arm in from underneath. Wonder if I really need all 8 cylinders anyway....F**K THIS CAR!

 

do you have it up on stands yet? If not do so. Then pull the fender well out and youll be amazed at how easy it is to get to things from there...

 

Have you tried a long piece of vaccum tubing? Slip it over the end of the plug where the boot goes on. Put a short 1/4" bolt in the other end so you can turn it easily,you can almost thread the plug all the way in this way. Usually I make the tubing about six to eight inches long but sometimes cut it accordingly. Works very well in tight spots

 

It has been on stands, with the wheel wells out for over a week. I have also tried the tubing trick first off, that didn't work either. The threads look fine, the plug came out easy, but I can't get a new one to start in that hole. All the others were easy (with the wells out). What kills me is the plugs that came out looked fine, of course you don't know that till they are out, and that's the easy part.

 

I can understand your frustration, but don't let this ruin your life, or your desire to keep and enjoy this car.

I strongly suggest you seek help at this point. If the hole in the head has been cross-threaded, it may not matter how much time you spend trying to get another plug started in there, or how small your hands are.

Take heart. The very worst this can mean is that the cylinder head comes off, and the plug hole is repaired. Yes, it'll be a hassle, and will cost some $, but it'll be no worse than changing out a head gasket. And it's quite possible that a good tech can re-tap those threads for you with the head in place.

With any luck the threads are still good, and all that's required is somebody with smaller hands and/or more dexterity. The number 8 plug on an LTx engine in a C4 can be very challenging. I have deep experience wrenching on cars, and have above-average dexterity, but my hands are not small and I had an "interesting" time getting the #8 plug out/in on mine, too.

I'd encourage you to contact a local Corvette specialist, and ask them if they'll handle the repair for you. This has obviously long-since crossed the threshold of pain for you to where it's no longer worth it to you to continue to try to fight your way through this yourself. It's just not worth it anymore. Cash in some Fun Ticket$, and let an expert put this problem behind you while you sit at home with your feet up drinking Good Cold Beer.

Best of luck with it.

Be well,

SJW

 

I know what you are going through. I also changed my plug wires at the same time so I cut off the end of an old plug boot and started the thread that way. It took me some time but you just got to stick with it. It took me a weekend to change all the plugs! If it' any consolation the left side is a bit easier. Hope this helps.

 

If I knew a local mechanic who worked on these, I'd do it in a minute. Anyone know one in Colorado Springs? I can't see how it could be cross threaded when I've never got the threads to catch since taking the old plug out, and besides, the threads look fine from what I can see, which is nearly one whole side that is visable.

So whats worse if I do find a mechanic, driving it there without a plug in #8, or trusting a tow truck operator and his grappling hooks?

 

Do not run the engine with the plug missing. Tow the car if you have to, or see if you can find somebody in the area to drop by and lend a hand. If I lived in the area, I'd come over and get it done for you. I suggest you post a request for help from any area Forum members (start a new thread with this in the title). I'll bet there's a Forum member in the area who can help you put this behind you.

Be well,

SJW

 

I'm sure that you have already looked at this but here goes any way... Take a close look at the lead thread on the plug it may be slightly damaged we encountered this many times at the dealership that I worked at. If you have a bench grinder with a wire wheel on it you can smooth the threads using it. Just another thought. Or maybe try a different plug in that cylinder

 

It may not be the head or the hole,it may be the plug. Try a different plug. It would'nt be the first time I've seen/heard of a plug that would'nt start. I would do that before I called in the hired guns..