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Johnienhuis

Posted 12/9/2025 19:50 (#11463815)
Subject: Thermostat Repair Information for Case IH Flagship Combines

Red River Valley and Devils Lake Basin

The below post is something a compiled so people would have the information they need to repair the thermostat in Case IH flagship combines. The thermostat pictured is out of an 8230, but I know an 8120 is the same. I believe this applies to many of the other flagship combines but I could be wrong. Anyways, please use this information to repair your thermostat instead of spending $700 on a new one.

First off, the most common failure on these thermostats is that the main seal fails and the engine never reaches operating temperature due to coolant constantly bypassing even when the thermostat is closed. The seal is 70x90x10mm seal and it is recommended to replace with a Viton seal. I have pictures attached showing seal (Picture #1) and you should be able to see the size as well. I purchased a TCM brand seal part # 70x90x10VTF (Picture #2). This can be purchased through Motion Industries and I am sure other places as well. Case also has a seal kit that includes the main housing o-ring, but I find that this is not necessary to replace normally. The CNH part number is 5801472355 (Picture #3)

The less common failure is that the seal at the bottom of what I will call the thermostat cage will fail causing the same symptoms of not allowing the engine to warm up during idle. This part has 2 different designs(Picture #4 with failed seal Picture #5 with no seal design), so if you have one with the rubber seal (Picture #4). Purchase CNH part # 504263917 (Picture #6). This will give you the design that doesn't have the rubber seal and therefore eliminate the problem in the future.

Any time that the thermostat housing is removed it is recommended to replace the gasket that part number is CNH 500362150 (Pictures #7 and #8)

Finally have several other pictures of parts breakdowns and part numbers for reference is someone needs that information. I find that this information is difficult to find on the mycnh website under the make and model so this may be helpful to someone. If someone has questions they can send me an email.

Picture Descriptions
1. Main seal in thermostat housing
2. New seal in box showing part number
3. CNH seal kit showing part number
4. Thermostat cage design with failed seal shown
5. Thermostat cage design without seal that is new
6. CNH kit to fix failed thermostat cage seal shows part number
7. Parts breakdown
8. Parts breakdown part numbers and descriptions
9. Parts breakdown part numbers and descriptions
10. Thermostat cup (part that actually moves to control coolant flow)
11. Thermostat housing assembled except for spring retainer this is the easiest way to assemble. Just squeeze the spring down with the retainer and rotate once you have it down far enough.
12. Thermostat housing disassembled

Edited by Johnienhuis 12/9/2025 20:03