There are several threaded holes in the front area of my 1st Gen. 1989 engine.

The bolts that held the A/C on seem to be the same size as these holes.

These bolts take a 15mm wrench.

I assume the threaded holes are communist/metric.

They are a hair larger than 3/8 and a 3/8 nut will not fit.

What size are these threaded holes??

What size metric tap will I need to chase and clean up the threads??

Many thanks for help on this.

 

Please, anybody.

 

I wish I knew...try posting on the 2nd gen engine and drivetrain section for more exposure....better yet, PM infidel, I bet he knows!
greg

 

I had my truck torn down pretty far last month. I think all the fasteners cummins used were metric. Buy a set of thread gauges (cheap) or compare to a tap and die set to check the exact size.