Soooooo… oh wait there is a meme for that! 😅
Ever been in this situation or you just stripped your bolt and now reading this? Yeah… I feel bad for you. In this post, I will talk a bit about how to fix the threads and also a solution that I used when I messed up the oil pressure switch thread inside the aluminium cylinder head.
Our LittleWagen VW T3 rebuilt 1.9td AAZ engine was almost assembled when I tightened the last oil pressure switch in the back of the aluminium cylinder head and… AND… it went from tight to really loose. 🤬😭
Had to take everything apart again to get the cylinder head off cause you don’t want any metal shavings inside your engine! Ordered new cylinder head bolts and gasket.
So there are few ways to fix this:
1. Weld, drill a new hole and rethread.
2. Drill the hole bigger, rethread and use helicoil.
3. Find a bigger oil pressure switch, drill a bigger hole and rethread.
Don’t try to fix it with liquid metal, alu-foil or super glue! It just won’t last.
Nr. 3 is how I decided to go.
Old thread THAT I MESSED UP!! was M10x1.0. So I went online and searched oil pressure switch with a bigger thread but the same pressure switch, in our case it was 0.3bar. Finally found BMW E30 switch with M12x1.5 thread.
For the M12 thread you need to drill a 10.2mm hole but inside the aluminium 10mm will do.
Filled the hole with lots of grease to prevent metal shavings from falling in oil channels.
Wrap masking tape around the bit, keeping the edge closest to the bit’s blade on the mark. The edge of the tape acts as the drill bit’s depth gauge. Never drill deeper than this point.
M12x1.5 thread tap.
Rule of thumb: Half turn into the material and then a quarter turn back. This will prevent vlogging the tap with the shavings. Use some grease and take your time!
New thread done! Clean all the metal shavings and flush the oil channels with air and brake cleaner.
I used a BMW E30 oil pressure switch with a new washer.
Test fit the bolt in its hole if everything done right it should travel in and out freely. Once hand-tight tighten as needed. Use a torque wrench.
Don’t use old bolts and head gaskets!