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Hi all,

I'm removing a couple of bolts that are in covered with undercoating. They are in a hard to reach area, so wire brushing is difficult.

Has anyone use any potions (sp?) or concoctions to clean them off? ...lacquer thinner or propane torch perhaps?

I'll be back in the garage this weekend to begin the process of removal. So any suggestions?

Thanks,

Mark

Nasty stuff that undercoat! It will burn - at least the stuff on my car did - so not sure the torch is best. I used heat from a heat gun and scraping to remove the undercoating followed with solvent wash to halfway clean what's left. Lacquer thinner might work better but unless the car is going to be redone, not sure I'd use it or acetone because of possibly running or getting it on paint somewhere.

If the bolt is large enough but not terribly long, perhaps heat and an old battery post brush followed by a squirt of solvent would clean enough off for a wrench to grab and unthread.

Has anyone tried a "needle scaler"? If they work, my casual search shows a wide variance in price - roughly $200-$700 has anyone got a recommendation for a good value for this tool?
Thanks.

Harbor Freight for probably under $30.

Yeah. If it is only needed for 15 minutes worth of use. That's about how long my harbour fright swazall NEW OUT thE box) lasted. Their hand tools (not power driven) are pretty good tho.

If you need to remove a lot of undercoating, wait till a freezing cold day and attack it with a needle scaler or just an air chisel set on a low pressure. Cold=brittle=falls off when the sheetmetal is vibrated.

If you just want to unscrew a few things, choose the correct size socket from an old set and grind (6) 45 degree chamfers on its edge in line with the hex. Drive the socket on with a hammer to clear the undercoat away.

I used a propane torch and just put enough on it to make it soft but not to burn. The heat de-crystalized it and then it peeled right off with a putty knife.

Update. I was out in the garage this weekend. I had just hit the nut and threads of the bolt, with the propane torch for about 5 seconds or so. The undercoating didn't burn or melt. But it is apparently so old and dry, that following up with a wire brush takes it off.

Although, I forgot how brittle these bolts are. Most of the bolts are breaking. The last time I removed a front fender, I think that I broke almost all of the bolts.

Interestingly, I found that the band clamp that holds the fresh air tube to the driver's side cowl was apparently mis-installed at the factory, and then undercoated. There was a big gap that had to be letting in water coming off of the front tire.

Thanks,

Mark

Use an impact gun/wrench, I have found they do a better job at removing old nuts and bolts without breaking them compared to a regular wrench.