farmall engine overhaul

so the other day while I was hauling manure with my farmall 130 I stopped for a second to do something and when I started moving again the engine started making a significant knock. I immediately parked it and shut it down. Pulled the head off and found that one of the throttle plate screw heads had sheared off and made it into the #2 cylinder. No major damage done, a few marks but no major scratches or dents. Changed rings and bearings while I had it open and when I got it put back together the head gasket leaked coolant pretty bad. Took it back apart and tried a different gasket, same thing. Took it apart again and checked for flatness on the block and head and the only major thing I notice is that the cylinder sleeves stick up slightly above the block. I put the straightest edge I could find on it and can't really notice any gaps but I question how perfectly flat my straight edge is.
My questions are these:
1. How does the head of a bolt just shear off inside a carburetor?
2. I've never overheated the engine or had any trouble before the screw made it knock so how could my head warp?
3. Why would the sleeves be pushed up like that?
4. Should I quit guessing and just take it into a machine shop? I need this tractor running about 4 days ago and am trying to avoid a major disassembly. Any help or guidance is greatly appreciated.

How high are the sleeves? I think they should be about .008 above the block.
The screw may have been loose and the butterfly plate may have worn the screw enough that it sheared it off, or it was overtightened and popped off due to fatigue. Either way it was just bad luck.
My guess is that the warping might have happened if you loosened or tightened the bolts incorrectly, or the heat and cooling cycles may have caused some stresses in the head, which only appeared after you remove the bolts.
SDE

[b:23e24db90e]1. How does the head of a bolt just shear off inside a carburetor?[/b:23e24db90e]

Don't know, but I've had it happen more than once. Brass parts seem do less damage than steel.

[b:23e24db90e]2. I've never overheated the engine or had any trouble before the screw made it knock so how could my head warp?[/b:23e24db90e]

The head could have been warped long before this. Overtorquing or improper order of torquing could have led to warping, but so long as it was tight, it may not have leaked. It could even have left the factory with an unseen issue, but so long as it didn't leak, it wasn't an issue for them.

The torque specifications have been upped when tightening down these engines' heads. Offhand I don't remember what the torque recommendation was for the last engine I did, but I remember it was higher than any manual I had listed it. If you have an older book, or an IT/I&T manual, it may be wrong. Ask your gasket supplier for the mfr.'s recommended specs.

AG

Did you put anything on the head gasket? I usually use spray
copper sealer on Farmalls and Indian Head Sealant on all
other old engines. I know folks say that you shouldn't need to
with specific kinds of gaskets, but I always do. Just always
have.

You didn't mention whether the leak was internal or external. I have an A that leaks a little externally depending on its mood but none internally. It could be a crack depending on what you are seeing. That's not terminal by any means.

Take the head to a good shop and have them check it out.

Question 1:
Manure happens.

Question 2:
The head may not be warped. Did you thoroughly
clean the surface? Wet sanding with 180 sandpaper
will get a good sealing surface, do same to the
block. Then recheck with a good straight edge.
Those are forgiving engines, thick head gasket,
heavy castings, they are designed for field repair
with less than prefect conditions.

Question 3:
Not sure what the specific measurement should be,
the manual should tell. But again a good straight
edge will tell a lot, mainly if they are all the
same height. But, depending on the fit, some
sleeves press tightly into the block, some sit
loosely. If they are loose fit, it is possible
they could have come up when the head was removed
and the engine turned over. Once they come up,
rust and sediment will get under them, and they
will have to be removed and the bottom of the
block thoroughly cleaned, and new orings
installed. If all the sleeves appear to be the
same height, I would assume they didn't move, but
if they are of different height...

Question 4:
Again, invest in a good straight edge, clean the
head and check it. It's probably better than you
think. A concern I would have is a possible bent valve with the screw getting in there. You can check then with diesel poured in the port, look for leakage around the valve. If all checks out, go back with another new
head gasket, tap all the bolt hole threads, wire
brush (do not run a thread die) the head bolts,
use some sealer around the perimeter of the
gasket, like Permatex if you'd like, seal the bolt
heads too on the wet holes, oil the threads.
Torque to spec in a circular pattern starting in
the center, working out. I like to go 1/2 torque
first, then full torque second pass, then keep
repeating until there is no bolt movement. Then do
it again when it's hot.

Also, a head surface can be true to a straight edge, but could have been ground improperly. We just had a TO-30 head redone that was true, but several thousandths more was taken off of the front of the head than the rear at some point in it's lifetime.

AG

If it was not leaking coolant before it ate the tiny little screw, it should not be leaking now.

As the other poster said, sleeve "standout" is NORMAL.

Did you wait 'til the engine cooled to ambient before removing the head?

Did you have the head and the deck surfaces SPOTLESSLY clean before bolting the head back down, using a quality gasket (FelPro or equivalent)?

Did you torque it down in the correct sequence, to the correct "spec", with an accurate torque wrench?

Did you re-torque it after it was run/warmed up?

So, just where is it leaking? To the outside or in the oil pan?

New or used gaskets?

Rick

I rebuilt the engine in my 1954 Farmall Super A two years ago. I bought a Fel Pro head gasket and it said on the package." Sealer required." Ive rebuilt lots of engines in my life and have used mostly Fel Pro gaskets and that was the first head gasket from them i had ever gotten that said that on it.I sprayed it with the copper head gasket sealer and installed it. I cranked it up and let it warm up and retorqued the head and it hasn't leaked a drop in two years.

A lot of unknowns as others have pointed out.

I'd definitely use copper spray on a new head
gasket.

Make sure the bolts/studs are oiled to get a
proper torque reading... and what are you torquing
them to?

Not sure about the 130's but the older farmalls
used to spec a really low number, which was later
upped to something more reasonable... I just
can't remember the numbers. I believe the new spe
was around 85 ft/lbs but don't quote me on that.

The patter is important, working from the inside
outwards.

As for why you lost the head of the screw in the
first place - could have been over tightened when
installed, and just picked that time to finally
fall off.

Or maybe the saft is worn and the plate is binding
in the carb - I'd check that.

my keyboard seems to be sticking... lots of letters being left out!

Thanks for everyone's responses.
Both head gaskets were brand new. The second one was a felpro.
Engine was cool when the head was removed and was torqued in stages using the proper sequence.
Coolant is leaking internally and externally and in some spots is coming out from the between the top and bottom gasket layers.
I did not receive any instructions with either gasket and did not use a sealer.
Can I reuse the felpro gasket that has already been on there?
I'm going to scrutinize the head and block today and see if there is anything I missed.
Thanks again for the advice. I really do appreciate it.

I have a couple Farmalls and have always been told that you have to retork the head after you run it at operating temp, you'll have to reset your valves also. It always pulls down some more on the second time and I've never had one leak when doing it this way. I also always use copper-kote also.

My manual said that for my engine serial number the head bolt torque is 65. Later models are 85. Maybe I should have gone to 85 and that is my problem.