Temp sensor plug.

[Tinkerr]

Anybody had any success removing the plug in cylinder head for the temp. sending unit? I had the motor rebuilt (1968 396/325) and the guy put the heads on the opposite sides of the motor. Now the open hole for the sending unit is on the passenger side. The first attempt to remove the plug resulted in 3/8 reducer breaking. Any ideas are appreciated. Thanks Paul

[betarho]

I’ve experienced this same issue. The solution became taking  the head off and heating it up with a torch. It finally got hot enough to come loose.

[Tinkerr]

I'm trying to avoid taking the heads off, I could just swap them to the correct sides at that point, I installed a $200 set of Cometic head gasket I'd hate to sacrifice if I can avoid it. Thanks Paul

[169INDY]

Humor me here.

Without any coolant, Obtain some welders cloth Mineral cloth or fiber-glass salmon cloth & mask area to protect, Use a propane hand torch and gently heat the head area around the plug and or just the the plug directly for just a little but to get some heat into it. Then use a birthday candle from the kitchen and place on the thread area and see if it wicks in like solder would, then resume attempts to remove.

Use something like this: 1/2 In Sq Dr Drain Plug Socket Set - 4 PC
https://www.toolsource.com/12-in-drive-metric-socket-sets-c-194_252_258_724/12-in-sq-dr-drain-plug-socket-set-4-pc-p-52621.html

I have broken wrenches by just jamming in a 3/8" drive  wrench & needed the above to be successful.

More Ideas from the forum should help also.

JIM

[Tinkerr]

I've been tempted to try the heat, but have been holding off. looking for other options first. I was going to use a oxy/acetylene for heat source, not sure how hot I want to get it though. My son in law is going to bring me a Snap-On 1/2-3/8 reducer for use with a impact tomorrow. Going to give that a try. The mechanic said we may have to drill it out and use a easy-out to remove the remaining remnants. That's a last resort. Any and all ideas are welcome and appreciated. Thanks Paul

[z28z11]

Apply PB Blaster or Kroil to the threads a couple of times before trying to remove it. Good thing about having the head bolted up is having a pretty secure platform to wrench against. A brand name breaker bar with a cheater works fairly well, you can at least feel the torque you are putting on the plug. Don't use an El Cheapo Offshore - I wouldn't trust the steel or the temper. I used this routine on the plugs in an intake recently, took my time and liberally used PB Blaster on all of the threads, never broke a plug or a wrench. Older Craftsman breaker bars and extensions -

Regards,
Steve

[Stingr69]

Drain coolant, oxy-acetylene "smoke wrench" on the plug until it gets dull cherry red, then spray with PB Blaster and it should almost back itself out.

Propane is not hot enough.  Pretreating is probably a waste of time (and hope).  Those plugs were installed a LONG time ago.

[Tinkerr]

Update on the plug. I won... I tried the heat and 1/2"-3/8" impact reducer, that rounded the plug. Next I drilled out the plug out to 7/16" and used a air chisel hoping the shock would loosen it. That didn't work. I used the air chisel to cut the plug off flush with the head, then used a big easy-out/screw extractor next, It still wouldn't budge until I added heat and out it came...Thanks for the help. Paul