Over the weekend I checked out an 85 GS that was for sale.

I wanted to give it a compression check. When I tried to back out the trailing spark plugs, they really resisted being turned--more than I expected. On the front plug, it seemed like I had to turn it at least a 1/2 turn (rough guess) with the socket wrench before it was loose enough to be backed out the rest of the way by hand. On the rear plug, after about 1/4 to 1/3 of a turn I didn't feel decreased resistance so I just stopped wrenching. Did not feel right. (Removed the leading plug instead for the compression test--it wasn't in there quite as tight.)

Those plugs must have been really torqued in there. It just seems that removing plugs on my own car has always been a lot easier. The owner claims that anti-sieze was used when the plugs were last replaced.

Anyway, wondering how badly the threads in the housings might be damaged if those plugs have actually been overtorqued. Any remedy if or when that engine would be disassembled?

Thx

 

I have seen antisieze gum up plug threads before. So long as they thread back in tight, no worries. If you do take the motor apart in the future the housings will probably have severe chrome flaking anyway and you won't reuse them.. if not, you could try running a tap through the threads or get a helicoil in the right thread pitch to ram in there.

 

OK. Thx. There was definitely no slop in the plugs when threaded back in and they seemed to seat tight so I'll chalk it up to gummed up antiseize.

 

It's possible that the plugs were just horribly fouled, too... I've had similar with other cars, where it took a turn or two to break all the crap off the plugface.

I tend to work such like a tap in reverse; quarter turn out, then back in an eighth, then out a quarter. Takes a while but gives a better chance to things to clean up.

If the first part of the next quarter-turn out still feels too stiff, there may be mech damage.

 

in california we don't have rust, so basically the ONLY way to screw up a thread is with anti-seize... it should just never be used...

 

i know alot of ppl that have cross threaded spark plugs before. they wil still sit tight and you may never have a problem but if its a concern of yours its a possability.

 

I've seen plenty of rust in Cali...

In any case, the damage to the threads could be severe to miniscule, its difficult to tell. If you want you can chase the treads or heli-coil like mentioned earlier. Also another thing, Drivin' Diver is onto something there. Ford's Triton V8's are notorious for a similar problem where their ridiculously long spark plugs become sooted or caked with carbon and become difficult to remove. In many cases the spark plug ends up breaking in half and you have to use a special tool for that particular engine to get it out. Silly Ford, you'd think after twenty some odd years of spark plug issues like that they'd figure it out.