Farm Equipment - Leak around thermostat housing

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Leak around thermostat housing

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=160608
Printed Date: 18 Jul 2025 at 5:18am
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Topic: Leak around thermostat housing

Posted By: rodnil
Subject: Leak around thermostat housing
Date Posted: 02 May 2019 at 9:34pm

I have an AC 200 that has had a slow leak at the thermostat housing. The anti-freeze ends up on the alternator causing it to be rebuilt. I had it rebuilt today and replaced the currant thermostat and gasket. The gasket was thick but the new one was thin. I did a very good job of removing all of the old gasket replaced the old thermostat and gasket with new of each . Started the engine and the leak was worse than ever before. After looking at it closer it appears to be a gap on the outside edges of the housing and the elbow going to the upper radiator hose. A thicker gasket is not the answer. Will gasket sealer work? Anyone else have such a problem and if so how did yo fix it? I'll check Agco tomorrow to see if any of the two parts are still available

Replies:

Posted By: 57WD45FarmUse
Date Posted: 02 May 2019 at 10:17pm

Hi there. Well ya got the surfaces nice and clean... how’d ya remove old gasket? Ive seen this one fella get a lil to rough with his ole pocketknife

Ya could try permatex the right stuff. I’ve used it to seal up a cuple situations that are similar to what ya describe

Posted By: rodnil
Date Posted: 03 May 2019 at 5:26am

I was very careful removing the gasket. Someone before me may not have been as careful, thus the leaking before and the thicker gasket. I'm guessing the next step will be to replace the neck piece (hoping to get a true flat surface) that the radiator hose connects to, and maybe replacing the part which is bolted to the block (again looking for a true flat surface). Finding these part will be my next step.

Posted By: jaybmiller
Date Posted: 03 May 2019 at 5:59am

I'm thinking 1 or the other part isn't really,really flat and true so I'd use a wide flat bastard file and 'mill' the parts. With a good square edged file, you can 'mill' ( clean up) the lips( if there are any). I've done this before and usually see quite a difference around the mounting holes. Also if there is a lip, that goes into the housing, file it down as well.Maybe it's a tab 'tall' and preventing the housing from mating totally flat.

The fact the original gasket was thick indicates they weren't using computer guided CNC machine when it was built !

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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)

Never burn your bridges, unless you can walk on water

Posted By: mechanicmarty
Date Posted: 03 May 2019 at 6:28am

If you can check how true flat it is with a small straight edge to make sure it doesn’t have a warp in in. Also if the housing has bolt hole that go through it and threaded holes in the block look really closely for cracks. I had a Mack engine water pump with what I thought was a leaking gasket. Turned out the threaded holes in the pump housing had tiny cracks(barely visible) so each time we would tighten the pump on the housing it would leak. We replaced the housing and she was good to go.

Posted By: rodnil
Date Posted: 04 May 2019 at 3:42pm

GOOD NEWS !!! I ordered a neck which sits down over the thermostat and is connected to the radiator hose. Thermostat and gasket back in place bolted the new neck in place started the engine NO LEAK, I let it run for a good 30 minutes and no leak.

Posted By: Dave(inMA)
Date Posted: 04 May 2019 at 4:41pm

Sure is nice when you win one, yes?

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WC, CA, D14, WD45

Posted By: rodnil
Date Posted: 04 May 2019 at 7:49pm

You bet it is !

Posted By: Dmpaul89
Date Posted: 06 May 2019 at 10:04pm

I had the same issue on my 7000. the upper housing is cheap pot metal. I "machined" it flat and used JD gasket maker with a new gasket. I think they get over tightened, which bends the metal. holding now.