No cooling of the is necessary. the nut has expanded and broken free of the rust bonding it to the bolt.

As soon as it's glowing, or close (many times you don't need to get it glowing, though heat exchangers I always do), take it off.

it just evaporates at those temperatures. You could use a regular mapp torch and that can work shooting some PB Blaster in there after heating up

Good question. If you've never done it before, clean with a shot of brake cleaner and let dry, then apply the heat.


Something else to consider in general. Penetrants and heat don't give you license to just gorilla a stuck nut off. Part of the fun, for me, is working a nut off and getting a feel for when the bolt/stud is going to break. If you can get a tough nut to back off a little, hit it with some penetrant and turn it back ON. Work it back and forth. It's a great feeling when it finally comes off after a few minutes.

Yes it is! Last year I was working on the car and when I went to disconnect the left axle from the hub I found that one of the flange bolts had sheared off deep inside the hub. Uwanna was over at the house at the time. I didn't have a set of EZ outs small enough so he went back to his house to get a set. While he was gone I drilled a pilot hole and shot it with Kroil and let it soak in a while. When he got back the EZ out worked like a champ.

I've learned the hard way that sometimes patience is the best tool in the toolbox. It was fortunate that I had to wait on Uwanna to get back with the EZ outs. Otherwise I probably would've rushed it and made a bad situation worse.

Actually you have, it's already been mentioned in this thread -- Wurst Rost Off. It uses extreme cold instead of extreme heat to perform the same function, which is to break the rust bond between the bolt and nut due to differential expansion (in the case of heat) or contraction (in the case of cold).

Among commercially available penetrating oils, Kroil seems to be the best (aside from a homemade brew of ATF and acetone), but no penetrating oil is going to get inside a rust bond without breaking that bond first, using either heat or cold, or some mechanical means such as a sharp impact from a hammer.

Locktite Freeze and Release I bet is the same type of product. Have not tried either.

Used CRC freeze off (and the smoke wrench) on my oil lines and the nuts spun right off.

For real problematic frozen studs or nuts you'd be amazed how fast they come off if you simply MIG weld onto them. This applies a ton of heat very quickly but I suspect the electrical current flowing through the threads also has some effect. I've used this method to remove broken studs and also remove bolts that won't come loose. For bolts I just weld directly onto the outer part of the bolt, you can no longer use a wrench on the bolt but grab them with vise-grips and they usually come out easily.

Wow. Can you explain the process briefly? It took me days to loosen up the lines with spray Kroil and a mild application of propane.

Apply a liberal amount of CRC Freeze Off. It works the opposite of heat, helping to break the seal by chilling the nut. Wait a bit for the penetrant to work its way up the threads, then hit it with a MAPP torch to get the nut nice and hot. The contraction and expansion seems to work for me, but YMMV.

I was popping the pistons from the calipers ofmy Lotus Europa that had sat for over 20 years yesterday. One piston would not move when I hit the air. So I laid the caliper on its side and then soaked the offending piston with PB Blaster. Two hours later, I blasted the air, and it popped right out.

Not saying this will happen all the time, but it never hurts to try.

Thank you.

Same with me on a 60's Datsun 2000 Roadster. Waited a day though. Boom, right into a bucket. Was able to save them with only new seals.