Used a new penetrating oil on a seized injector and it actually made things worse.

Sprayed it on a Duramax injector that was stuck, let it sit overnight, and the next morning the threads were galled beyond saving. Anyone have a go-to method for this that doesn't risk turning a tough job into a nightmare?

3 comments

3 Comments

sagecooper1mo ago

My old boss at the diesel shop swore by a 50/50 mix of acetone and ATF, and I've never seen it hurt threads. The key is to keep it wet and not let it dry out. Those commercial penetrants can leave a gummy residue that acts like glue once the carrier fluid evaporates. For something as precise as injector threads, I'd stick with the homemade stuff and apply it a few times over an hour with a little heat between sprays.

karencampbell1mo ago

Let it sit overnight" might be the problem there. Some of those penetrants can actually cause corrosion if they dry out on the metal. Next time, maybe try a shorter soak with some heat instead.

evan_cooper731mo ago

Oh man, @karencampbell is totally right about the corrosion risk. I learned that the hard way on an old truck bolt. Letting it sit too long made a real mess. What worked for me was hitting it with the penetrant, then a quick pass with a heat gun for a minute or two before trying to turn it. The heat seems to pull the oil in deeper way faster.