I wanted to drain and flush out the cooling system, since there were major grit and particles when I drained the radiator. My daughter-in-law just got the car and loves it. It has not been taken care of. Well, when I removed the coolant drain plug on the block under the manifold heat shield, all hell broke loose with the threads on the plug and worse with those in the aluminum block. Here are pictures of the threaded hole and the plug. I have a new plug, but am asking what I might do to either repair the threads in the block or seal the hole some other way. The new drain plug starts in the hole and then gets real hard to turn. Threads are messed up.

thanks,
Dave
oh, yea, 1990 GS B18A1 3-door, automatic, 160k miles.

 

You can try "chasing" it out, use a tap of the correct size to chase/clean the treads up, it may even work with a steel bolt of the correct size, then some Teflon tape on the bung, [new bolt] and you should be good to go.

If treads are damaged beyond repair, [chasing] just pick up a Helicoil of the correct size...

However, spend some time chasing the hole first, you can always use the Helicoil if chasing does not work.

Once you have the correct bolt, carefully tread it in as far as it will go, [till it gets tight], then "force" it in a little at a time, [no more then a 1/4 turn at a time] unscrewing it each time to clear any debris/shavings, some oil on the bolt will help, continue untill treads are cleaned.
CAUTION make sure the bolt you use is not long enough to hit anything inside the block, or use tape on the bolt to mark max depth.

Good luck. 94