View Full Version : Engine Broken Bolt - Nitric Acid?

05-26-2011, 04:23 PM
Even though I soaked for 3 days the 4 bolts for the Y pipe with PB Blaster, one of them broke during removal. I tried using a left handed drill bit to remove it, but it didn't budge. Tried an extractor tool, but still nothing, and don't want the extractor to break in there.

After reading online, I learned about using Nitric Acid to remove the bolt. Has anyone tried this? Any experiences they could share?


05-26-2011, 04:26 PM
Drill it out, and use a Timesert or Helicoil to repair the threads. I have never had anything good come of bolt extractors. And you are correct to be cautious - breaking off a bolt extractor in the broken bolt is a whole new world of pain, since the extractor is harder than your drill bits.

Don't go too deep, you will hit water. . ...

05-27-2011, 09:48 AM
If you used acid how do you prevent it from melting the part and only melting the bolt? There are too many problems with this. There is a method of reverse plating to dissolve broken parts called EDM for Electric Discharge Machining but the equipment is very expensive. At this point keep enlarging the hole with progressively larger drill bits till you can retap the hole. If you oversize it you can always get it back to original by using a thread insert like a Heli-Coil. The most important thing is to stay centered on the broken bolt so the new hole will be in the correct location.
David Teitelbaum

Delorean Industries
05-27-2011, 11:03 AM
The maximum depth you can drill this hole measuring from the matting surface of the y pipe and block is 1.035 inch. At 1.100 +- depending on the block casting you punch into the coolant jacket.

Best course of action is a helicoil kit. 7mm 1.0. The kits are self explanatory to use.