Replacing the Head first type

[steveo]

Hi all,
Just got the head for my 151 back from the machine shop.
All rebuilt and milled.
Had a bubblin head gasket leak (passengers side rear)
Also leakin into 2 of the cylinders. Noticed There was no gasket sealer (on the gasket) used previously when I removed it.
Read an old post from a member that had the same issues.

** below is the plan to put it all back right.
Hopin ya’all can give it a look over and if I’m missin anything or any additional suggestions to give me, please fire’m out.


Rick f- in that post suggested using a bottoming tap and clearing the threads and finishing the ones that were likely
Not completed. Sure enough that was the case with mine.
Specially where the leak was.

*( actually it was on the 503 that I read this issue)

Picked up some Permatex high temp copper spray for both sides of the gasket as Rick suggested in his post.

**question, never used the permatex high temp copper spray gasket, in this application do I assemble when the gasket spray is still wet, like a tube type permatex?

Cleaned the head, piston tops and sleeves specially at the leak area from burnin oil.

Drained the block from the drain port after Cleanin the head. Radiator was new about a year ago and looks perfect still.

I’ll use the called out torque settings from the manual and the application order.

Checked the compression before I tore it all down
100. W105
108. W108
108. W108
102. W108

Thanks for any suggestions.

Steveo.

[rickf]

I had to laugh reading your post here, I got as far as "bubbling head gasket and I knew right away what it was and then you mention where and that nailed it and then you mentioned my solution was correct. Glad I could be of help. It still amazes me how many of these engines have this issues. I wish I had a database of the serial numbers of the affected engines just to see if it was a select group or a worn out tapping tool that did thousands bad.

Spray the copper gasket on and let it dry. Compression numbers are a bit low but these things crank slow so unless you plan on a total rebuild to include bore and new pistons and rings and all the lower end bearings I would just slap it together. You can always pull the head later to do the rest of it, you are not going to hurt the head. Be sure to reset your valves since they will all be too tight now that the head has been machined assuming it was milled to make it flat.

[m3a1]

Last time I used the copper stuff, it remained rather tacky (I followed the directions precisely) so you'll have to handle it from the edges.

It (coupled with a new head gasket) did a lovely job, by the way.

[steveo]

Thanks Rick and M3A1.
I appreciate ya guys.
I’ll do exactly as ya suggest and yea valves will be reset.
Cold first then reset after warm up.

Rick i figured it was you on that response several years back on the 503.
And I was kinda shocked how many of the threads were needing to be cut and dressed. I would say significantly on at least 3-4 different bolt way passages. Others just cleaned up
The head was milled flat in the rebuild.

Planning as you said Rick to just reassemble and run it.

I’ll update the post after I get it all back together and runnin again.

Steveo
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[steveo]

Wanted to add that the rebuild guy at the machine shop informed me that I had some significant wear on the intake guides as well.
I was thinkin the exhaust would be worn, and they were but Makes sense as my 151 never had a heater installed and was definitely lookin original FDE when I got it, and it appears to be the base color so was prolly in some “sandy places”. Air cleaner likely not gettin all the maintenance it should have.
Good info for me, especially here in the cactus patch to remember to really keep that air filter clean.

[rickf]

Is this an A1? If it is and FDE means desert tan paint then the A1 was never painted that color in service that I know of. I am pretty sure that color was not used until later into the late 80's early 90's. All of the A1's would have been out of service by then. And in any case, the military back then was pretty rigorous on preventive maintenance so the air cleaners would have been well maintained. Any vehicle in service in a conflict area would be considered "severe service " and maintained as such by the motor pool. I do know that motor pool service really suffered after about 2000. I am not sure but I think a lot of the service was civilianized. I live right next to a base and actually in the ranges so I see the vehicles all the time and that was about the time I started seeing vehicles with lights out, smoking, bald tires. All stuff that would never even leave an old motor pool compound! Valve guide wear is usually from no oil changes or running low on oil. Or high mileage, which is usually not a factor on military vehicles. Do you know the history of the vehicle from the person you got it from? no air cleaner could definitely contribute to low compression readings but if it is not smoking I suggest you drive it for a month and then do another compression test. Sandblasted rings take out the oil rings first and they smoke, especially bad on deceleration.

[steveo]

It’s an A2. And as I said likely always tan.
But the head I have on this engine was the early type.
Not sure of the total history. Owned for several years by a friend of mine. Not sure where he got it. Az title. I drive it all over.
The motor Went through a rebuild as it’s got the plate on the drivers side of the engine. But who knows over 50 years what went on with it. I don’t know exactly when this motor was put in. I have had the 151a2 for a few years. How I got it from my friend John.
Smoked on start up or after just in idle for a while.
Hopin most of that was from the valve guides and the head gasket leakin oil into the cylinder.
I’ll find out soon enough.

[steveo]

Progress update.

After flushing the block and the passage way for the block drain located on the drivers side rear,
As Rick told me I ran a bottoming Tap down all the head bolt mounting holes, had a couple short ones passenger side rear and most all were “ crusty”. Huge difference.
Cleanin the block/head surface.
Copper spray for the new head gasket was definitely “sticky” so thanks for the info on that m3a1 and all the guidance from Rick here and on PM’s Worked out perfectly.

NOS exhaust manifold installed with a thin light coating of Permatex high heat ultra red where it attaches on that first model head I have to just give it a little extra seal because of some corrosion areas on the head is workin out great. So far about 155 miles on dirt roads and paved streets at tops 50-55 mph.

Permatex no. 3 aviation gasket worked great on the thermostat housing, radiator hose connections and the valve cover. First time usin it, darn good stuff.