Replaced radiator 2600 gas / temp gauge accuracy


New User
I have a gas 3 cyl 2600 and noticed fluid leaking from the radiator. I replaced the radiator, upper and lower hose. I also ordered a new thermostat figuring I would go ahead and replace it as well as the fan belt. It did not have a thermostat when I took off the housing and from reading these forums, I drilled a small hole in the flange and installed with the "cylinder" part of it facing the engine. I started the tractor and filled the radiator with the cap off until it started running out then put the cap on. The gauge always got into the red before but I want to make sure I am not overheating after this install. The temp light on the bottom right has recently not turned on when engaging the acc prior to starting every time. When I turned it off, both hoses and radiator were very hot to the touch. Any advice on the accuracy of the temp gauge or what I can do to verify this is OK? Thanks in advance for your help.


This post was edited by Mrfoo84 on 11/07/2022 at 06:13 pm.
If your tractor was built before 1979, and if your fuel gauge also reads high, then you have a faulty
voltage stabilizer behind the dash.
There is no "temp lamp" on the bottom right. There is a temp gauge on the right above the warning lamps. There should only be two working warning lamps on that cluster, one is the battery charge warning lamp and the other is the oil pressure warning lamp.

The radiator hoses and radiator being hot to the touch is not an accurate way to measure the temperature. It probably has a 168 or 180 degree thermostat and 168 degrees can be very hot to the touch, but it not too hot for the coolant to run at. Get an infrared thermometer gun and measure the temperature of the thermostat housing to find out how hot it is really getting. Accurate infrared thermometers are not very expensive these days. They are very useful for lots of things.
Had a similar problem with my 3600. Attached a mechanical gauge, engine was not hot. Replaced the sending unit, problem solved.
You can use a non contact IR temperature gun to check temps, pretty cheap at Harbor Freight.
On my 2600 diesel I can watch the temp gauge and it will go up and then drop when the thermostat opens. If you filled the radiator and capped it there's a good chance you have air trapped.
IF.. you say you left the cap off untill you could see the water flow.. then yes, the thermostat opened correctly, and bled out any air in the system. BUT.. that also means the water temp is at the thermostat setting. And if its 180 degree, then yes it will very hot to a human, not so much to an engine. Both hoses being hot is also a good sign of water flowing correctly. As others have said.. An ir gun is very handy for checking.. you can shoot the thermostat housing to get the temp of water leaving the engine... ie 185 degrees, then shoot the top of the radiator tank.. also about 185... then shoot the bottom of the radiator tank.. should be at 165 or at least 20 degrees cooler going back to the engine. This will correctly show everything is working as designed. Gas tractors with the thermostat located on the end of the instake manifold can more easily trap air,, and take longer to open correctly as they are too far from the engine itself. How ever the bleed hole will take care of this problem.
Thank you everyone for the replies and info. I bought the 168 thermostat from this site and had an IR thermometer for my grill. I measured about 168-170 from the housing, a few degrees higher at the top of the radiator and about 20-25 degrees lower at the bottom of the radiator so everything appears to be all good. The temp gauge read what you see in the photo I attached after 20 minutes or so. The fuel gauge reads pretty accurate so I don't think the voltage is any issue.
With a tractor this old, chances are that the instrument cluster and/or the temperature sender have been changed over the years, and if they aren't a matched set, then inaccuracies are likely.

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.