ZA Radiator Help

Spencer2598 · Apr 22, 2019

Hi all, I have a ?51 ZAU that is need some work. My Grandparents bought it new and it hasn?t had much done to it since the 70?s, from what my dad remembers. We retired it and got it running but now its time for a few more intensive jobs. It is needing a new radiator core and I have one ordered with gaskets. I know I?m going to twist off several of the bolts while taking the old core out. Any tips to make this easier or to make sure it doesn?t leak when I put it back together?

Also, in the near future, we are going to have to pull the jugs to find and fix an oil leak. It?s coming out from between them and then running down the crank case. This is something that neither my dad or I have ever done on this tractor and any help with this would be appreciated.

Once these are taken care of and we get the carb rebuilt, it will be ready to go.

Thanks for all the help!

ChrisQ · Apr 22, 2019

Use a 3/8" impact wrench to remove the bolts. Not as many will break. Weld nuts on the ones that break off and they make come off with the impact. May end up drilling a couple. I always assemble with all new bolts. Get an I&T manual before tearing into the engine. They are very simple to work on, but it is nice to have the specs. I would guess the block gaskets or maybe just valve cover gaskets are leaking.

bog · Apr 22, 2019

I just did one broke off 12 bolts. Heated the broke off stubs cherry red, then put vise grips on them. They came right out. Worked very well.

Spencer2598 · Apr 23, 2019

Thanks guys! That?s good to hear that the bolts might not be as much of a problem as I thought. Good ideas about how to get them out, I?ll remember these. I do plan on getting all new bolts, will normal bolts work or should I get some special type for this? I think your right and the block gaskets finally gave up. I?ll have to look into the I&T book.

shinnery · Apr 23, 2019

The I & T manual for most Molines, MM 201, is available from this site for $32.95.

T.R.K. · Apr 23, 2019

The I/T manual will be a big help with the oil leak repair. If the oil is coming from between the blocks, its either one of the block gaskets or there is an oil passage plug in the rear block that is leaking. That plug is in the same location the oil tube comes from the front block and goes around to the top oil pump shaft bearing.

The beauty of those engines is that you can disconnect the rods from the crank, remove the rocker asemblies, leave the head and manifolds on the cylinder blocks, and pull the whole assembly at one time out of the crankcase.

T.R.K. · Apr 23, 2019

Oh, I forgot to add: I did a ZB radiator once. I had to drill out about 6 of the bolts and two or three of the holes needed helicoils in them. I doped the new bolts with RTV and it sealed up o.k.

Spencer2598 · Apr 24, 2019

That is great to know they can be pulled without taking everything apart! I had wondered about that but didn?t know if it could be done. The tractor runs and sounds good so I hate to take it apart any more than necessary.

MMDEL · Apr 24, 2019

Wash, Clean everything on both sides. Then run engine till it starts to leak. Watch close so you can see exactly where it is coming from.Check highest points first. Don't need to take something apart and then find out latter the leak was in a different place.
MMDEL

Spencer2598 · Apr 25, 2019

The best we can tell, the leak is coming from between the blocks and runs down the crank cover under the weather pump. Unless there is something in between the blocks that could be leaking, it about has to be the
gaskets for the block and crank case. Am I correct in my thinking?

MMDEL · Apr 26, 2019

I have over a dozen Rs, Z, and Uni-s and it is quite unusual for a leak in that area. However anything is possible. If you absolutely determine that is where it is leaking, then it would be coming from the very left area of the blocks where the oil passage is to lube the valve train. Then as suggested remove the rod caps and lift the entire assy. up from the crankcase. You will have to do this slowly and rotate the crank as you go up so as not to scratch or damage the crank. No doubt your tractor will have cork gaskets. Do not replace with cork. Use the later style gaskets made of a harder material. With cork gaskets, if the blocks are tightened down a little too much (there never was a torque spec for this) the pistons will hit the top of the block and it will knock or sound like piston slap.
MMDEL

Alan K · Apr 29, 2019

You might be surprised on the radiator bolts. Some can be difficult but some come out fairly easily. The leak between the blocks could be from the oil passage or the oil passage plate that is held on with two round head bolts. Also, there are soft plugs in the blocks on each end where the rocker arms are which can leak oil.

Spencer2598 · Apr 29, 2019

Is there any way to tell on the leak or will we just need to start taking everything apart to find out? I know when its running, the oil only runs down from between the block right at the top of the crankcase. And doesn?t go the the right side of the tractor, only to the water pump side.

SWMolines · Apr 29, 2019

Do as MMDEL suggests. Clean the gap between the blocks out so you can get a clear view of the source for the leak. Might need to use air hose and/or pressure washer.

There are oil holes on the top of the crankcase that brings oil up to the cylinder blocks at the middle of the engine on the water pump side. If dirt and debris have collected in the gab between the blocks, the gasket can deteriorate over time and fail from the oil pressure.

I have seen that multiple times.

ZA Radiator Help

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bog

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