TIL an old diesel mechanic taught me a trick about injector cups that saved me a headache

I was working on a 2006 Freightliner in a shop near Nashville last month and this older mechanic, must've been around 65, came over and watched me struggle with a stuck injector cup. He just laughed and said "son, quit hammering on it, grab your torch and heat the block around it, not the cup itself." I'd been at it for an hour with a slide hammer and getting nowhere. He showed me his method: heat for about 90 seconds on the outside of the bore, then a quick tap with a brass punch. That cup popped right out on the first try. Has anyone else run into an old school trick like that that completely changed how you approach a job?

2 comments

2 Comments

skyler_kim156d ago

My grandpa taught me that same trick on a farm tractor about ten years ago. I was surprised how fast the heat transfers and makes the cup loosen up without damaging anything. Have you ever tried the freeze trick with penetrating oil for really stubborn ones?

skylerg176d ago

Oh man, that freeze trick is a lifesaver on the really stubborn ones. I had an old rusted bolt on my trailer hitch last winter that just would not budge after heating it up, so I sprayed it with penetrating oil and hit it with a can of compressed air upside down to freeze it. The crack it made when it finally broke loose was so satisfying, my neighbor came over to see what happened. Works way better than just heating and oil alone for sure.