My '72, work in progress

[Francis Marion]

Sounds to me like you have a blown head gasket. You should not be anywhere near full throttle at 55. I cruise at 55 at no more than 1/2 throttle. If you have to push it that hard there is something wrong in that engine and I suspect the head gasket considering how fast it overheats once you push it. Also the fact that you have no power.

I had this problem. #3 & 4 cylinders were sharing experiences and also leaking into the the coolant. My obvious tell was constant bubbles coming out the radiator with the cap off.

[whiterabbit]

Gonn'a check compression but I had a steady vac reading at the manifold and no bubbles in the radiator. Used the vacuum gauge to help tune the carb. and was getting a nice steady reading.

[rickf]

Check the torque on the head bolts, you may find a loose one and it is only blowing by at heavy loads and higher temps.
Even if you don't find a loose bolt it might be worth it to pull the head and see what you have. Not hard to do and gaskets are cheap. Cheaper than constantly throwing parts at it.

[whiterabbit]

Messed with it last night.
Checked the head bolt torque. Good
Vacuum readings. Stable at 22 inches
But I think I found out what's going on!
The rocker arms shaft was slightly rotated on the mounts. The feed tube was not all the way into the shaft feed hole and the shaft was rotated almost to the point where the hole was closed. Very little oil feed up top! Pulled the assm. and slid the rockers around, no scoring but just a little on #1 & 2. Cleaned and installed correctly. Tons of oil flow from the rockers now.
Will test run today.

[rickf]

Did you adjust the valves? If they are to tight you could burn a valve plus it would run lean which could possibly give the overheating problem.

[whiterabbit]

Didn't want to leave ya'll hanging. I caught hell doing the valve lash while running. Turns out I had too much lash. Did them with the engine off. Runs and starts great now.
The over heat issue??? The darn belts! While reving it up and messing with the carb I noticed the fan took a second to get up to speed. I thought they were tight but they are the old original belts and had been slipping at high speed! Tightened them up good and no more overheat. I feel like an idiot, stupid simple issue I should have caught. Oh well, time to order some belts. Live and learn.

[lpcoating]

Very nice picture -looks good...

[Fil Bonica]

It's the simple thing that usually bite you in the butt!
Good to see you found them.

Have fun

Fil Bonica

[whiterabbit]

Thanks all!
It wouldn't be back in service without all the help and knowledge from the good, no, great folks on this forum!
It's amazing to look back on the first few posts on this thread and see the condition of the jeep then and now. The wife is loving it and I sneak out with it every so often. Drove it to post a few days back and the rubber necking never stopped.
I guess I can wrap up this thread by saying again,
THANKS FOR ALL THE HELP REBUILDING MY M151A2