Helicoil installation on MB GPW L134 block. I had a miss, possible valve sticking, or worse, in my engine. The middle head bolt on the left hand side, in front of the carburetor, would not seat and would just rotate. A new bolt took to the treads but could not be torqued down. I removed the head and discovered the gasket at the non-seating head bolt was firing across the gasket to the middle two chambers. The treads in the block for the head bolt were gone. I took a good head bolt to the local auto parts store and got a 7/16 Helicoil kit. The kit does not come with a drill bit but the tap indicates the drill required. I drilled the hole and recommend using the head back in place to guide the drill. The drill went down freely over 1-3/4 deep into the water jacket. I tapped the drilled hole and the tap stopped at 3/8’ deep like the casing wall was preventing it from going further. On the day I had everything ready to assemble, I sprayed my gasket with copper coat and put it aside. I applied gasket sealant to the helicoil as advised, to seal the water jacket. Placed it in the hole and could only get it down 3/8”. The directions say the top of the helicoil must be ¼ -1/2 turn below the top of the hole. I had to remove it with effort. An hour and half of stooge confusion reigned until I retried the tap and forced tapping in 1inch depth. After that, everything went well in the 92 degree Virginia weather. Check the depth - what appears to be the bottom or a stop with the tap may not be.

Drill out the hole using a 29/64 size drill or whatever the kit states. Kit ID# is HC Recommend placing head down as guide to ensure a straight cut.

Tap the hole for new threads using the tap from the Helicoil kit

Vacuum filings out. You might want to cover the chambers and valves with masking tape

S ½-13X 2-1/4 Hex hd. Screw-diff, bearing cap screw Willys part Parts list ¼ ton 4X4 Ford Motor Company April 1942 Head takes 23/32 wrench, Shank is ½”, 13 threads per inch 38 Lbs dry 31 lbs wet TM = 40 lbs Torque for Diff cap screw