Big problem, 70 L34 Nova

[Bavss70]

I have an 402 engine that is ready to paint but I neglected to remove a plug for the TCS sending unit on the passenger side cylinder head. The plug has a recess for a 3/8" drive. I have tried a breaker bar drive on it, tried using a cold chisel to drive it and it is starting to look a little worn.
Does anyone with their repertoire of experience, had any luck in getting a plug out of a 30 plus year old head?
I am worried about trying an acetylene torch as perhaps the head would crack. If I drill it out, I may lose the water pump.
Some how, some way that plug is going to come out before we have to tear off the heads, etc. and go to a machine shop.
Many thanks in advance, John.

[RamAirDave]

In a similar situation on a car right now. Havent really gotten after it yet, but did find that a 10mm square drive bit fits a lot tighter in the square than the 3/8" bit.

Obviously wont help for loosening the plug from the block itself, but should at least reduce the chance of rounding out the square hole.


dave

[John Brown]

John

I've had good luck trying to tighten them up before trying to remove them. Don't have to tighten them much, maybe 1/8 turn or less. The old time blacksmith I got that trick from said tightening a pipe plug expands the hole a little and breaks the rust loose.

If it works, buy me a soda pop. If it doesn't, I'll deny everything . Good luck.....

[TDW]

I have removed lots of pipe plugs from old steam and hot water heating systems. Using a small propane torch, heat the plug up. Concentrate the heat on the plug. When it is fairly warm, melt some bees wax around the threads. The wax will flow into the threads pretty good. Let it set for a few minuets.Turn the plug both ways a small amount until you feel it break loose. It should come out this way. You can use a wax seal for a water closet [toilet] to melt into the threads.

[PeteLeathersac]

Lots of good ideas but be careful heating the plug itself as too much expansion could cause the head casting to crack? . Usually with seized items you need to heat the outside one of the two pieces (in this case the head) to allow it to expand beyond the inside piece (plug). . Have a straw or something w/ a tiny amount of water you can quickly put into the plug for a moment then immediately attempt to loosen it. . The water in the plug will cool and shrink it slightly smaller than the head and may allow you the difference for it to let go? .

JB's above mentioned trick of trying to tighten to get it to give first is a good one and often works well as it doesn't destroy the grabbing edge of the direction you need to take something off. .

Last resort, try one of the impact-driver tools. . These work great on seatbelt bolts etc. that seize but don't matter what happens to the area but w/ your head situation you need to be careful as the instant impact can carry through and cause a crack. .

I think a combination of all of the above may do it....Good Luck! .

~ Pete

[Bavss70]

Thanks all for your suggestions. We tried heating the heck out of the plug but she still wouldn't move. As a last resort I borrowed a candle, let the wax do it's thing for 30 sec and hit the plug again with the breaker car. Out she came like a piece of cake!
John.

[TDW]

Glad it worked John. Thats an old Plumbers trick.I have had lots of people laugh at me when I tell them it works.

[WILMASBOYL78]

He should have soaked it in Molson's....

wilma