Found a trick to get stubborn rusted bolts off without breaking them

I had a 2003 F-150 in my shop last Tuesday with a rusted exhaust manifold bolt that just would not budge. After trying PB Blaster and heat for 20 minutes, I remembered a tip from an old mechanic in Detroit: tap the bolt head firmly with a hammer a few times before you put the wrench on it. The vibration breaks up the rust crystals enough that it came out clean with a 15mm socket. Has anyone else had luck with this method or do you have a different go-to for seized bolts?

3 comments

3 Comments

rodriguez.diana1mo ago

haha yeah the hammer tap trick is legit. works way better than people think.

james_singh71mo ago

I get that the hammer tap thing works for some people, but I've been burned by it too many times to trust it. If that bolt is REALLY seized tight, tapping it can actually mushroom the head and make your socket slip off, then you're really in a bind. I've had way better luck with a careful application of heat from a propane torch let it soak for a few minutes then hitting it with a dedicated impact driver. The hammer trick is fine for surface rust but for exhaust manifold bolts that have been baking for 20 years you need more than a little vibration.

logan70521d ago

That 20 year exhaust manifold bolt situation is exactly where I learned the same lesson man. A little propane torch, some Kroil or PB Blaster if you have it, and a good impact driver has never failed me where the hammer tap just made a mess. Your mileage may vary, but I've pulled apart too many chewed up bolt heads on customer cars to go back to that old wives tale trick.