Discovered a trick for stubborn caliper bleed screws yesterday

I was fighting a seized bleed screw on a 2012 F-150 in my shop near Pittsburgh, and after spraying PB Blaster for 20 minutes I tried a heat gun on low instead of a torch. It broke loose in 30 seconds without damaging anything around it. Has anyone else had better luck with controlled heat vs. penetrating oil on brake hardware?

2 comments

2 Comments

jackson.sarah1mo ago

Oh man I've been there way too many times. Heat gun is actually my go to now after melting a rubber boot with a torch once on my buddy's old Silverado. I hit it with a quick heat cycle first then spray the PB on while it's still warm and that capillary action really pulls it in. The key is keeping that heat gun moving so you don't cook the paint or the rubber seals around it. I've also had good luck with a manual impact driver on those stubborn bleeder screws but you gotta be careful not to snap it off.

dixon.willow1mo ago

Slight correction on the capillary action thing. PB Blaster works by breaking down rust and penetrating, not through capillary action. Heat expands the metal and pulls the penetrating oil in as it cools, that part's right. Capillary action is more about wicking into tight spaces, like how a paper towel soaks up water. Good call on the heat gun though. Torch is way too risky around brake lines. Seen guys melt through a rubber line and lose all brake pressure. Manual impact drivers are solid for bleeders. I'd add a trick though. Tap the bleeder with a hammer first, just a couple light hits. Breaks up the rust crystals before you even put a wrench on it. Makes a big difference on those stuck ones.