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I received an assumed rebuilt engine from the previous owner and finally got the M38 ready to crank up after a 1.5 year build. Got the engine running but as it started to get warm, I noticed water/anti-freeze seeping out of #1, #2, and #4 head nuts on left side, front to rear.

Question: Can I just remove nuts, clean and put on some gasket sealer, and retorque nuts 65-75 ft lbs? Or do I have something else going on? i.e. should I remove the head. The exhaust is not putting out any white smoke so I assume the head gasket is good.

Thanks in advance. This thing is danger close to being road ready.

It's not the threads between the nuts and the stud that are leaking. It is the threads between the stud and the block on the studs that penetrate the water jackets that are leaking. Those studs should have had permatex #1 sealant on them before the studs were installed in the block. You should remove the head so when you reinstall the studs you can insure their installed height is correct.

Well Dang. Thanks for the info Wes, as always, the reason I come here for info. Man, I was looking forward to driving it this week.

Wes, You were completely correct. I removed the head and discovered no sealant what-so-ever on the head side of the studs. Also discovered 4 helicoil inserts, of which two were my culprit leaks. I'll get new studs, nuts, and head gasket and install along with permatex #1. Just need to find the height you mentioned.

Thanks!

Wes, I searched the manuals I have (TM9 series) and can't find anything mentioning the head stud height on the L134. Clueless...Can you help me out?

When studs have all threads they will usually post a setting height for them. If the studs have an unthreaded center then common sense dictates they only be threaded that far. If you continue to force them you can damage threads and crack blocks. If you had only removed the three leakers with the head still on you would not have been able to confirm a proper height setting on your studs.


Note the fattened ring at the block deck on the right side stud's
unthreaded shank. Then note that fattened area is missing on the left side stud.

Original Willys studs are getting hard to find. Many have used the m37' s studs.







When we only R&R a couple of studs leaving the head on we often have to double nut them and use a wrench to get them all the way in. If the stud you are installing does not have the fattened shank where it contacts the block you do not get that warning that you are in far enough.

Thanks...all my studs had the fattened rings on them, but I'm going to replace them with new from Kaiser Willys. The way you described I was thinking there might be a nominal height measurement, but I understand the seating issues.

Don't forget you need to warm up the engine and retorque the head nuts too!

Thanks Ryan...I got all the head nut leaks fixed, now I have one of the new exhaust studs leaking. Guess I'll pull it and goop it up with permatex too.