Rusted exhaust bolts made me pick between fire and brute force

Working on a 2012 F-150 in Detroit yesterday and the rear exhaust manifold bolts were totally seized. I had to choose between cranking my torch up to cherry red heat or just snapping them off with an impact gun. I went with the heat method and it worked on 3 out of 4 bolts but the last one still broke off flush. Has anyone else had better luck with a specific penetrating oil on rusted Ford exhaust bolts?

3 comments

3 Comments

victor_robinson16d ago

...man I used to be all about just hitting them with the impact and moving on, figured heat was too much hassle. But after a few of those flush breaks left me drilling and tapping for hours I had to change my mind. That torch method takes patience but it saves you a world of hurt when the bolt actually lets go instead of twisting off. I still keep a can of PB Blaster around for the easy stuff but for anything that's been sitting in Detroit salt for ten years it's heat all the way. The one that snapped probably had a hidden crack before you even touched it, those manifold bolts are just garbage metal sometimes.

lilya7616d agoTop Commenter

Agree with @victor_robinson, heat is the ONLY way on rusty stuff, period.

miller.rowan11d ago

Buddy of mine swore by the impact only method till he snapped a rusted bolt in his truck's frame. Took him two weekends to drill it out and retap the hole. Now he keeps a propane torch in his truck bed at all times.