Zetor 6748 tracktor

This has nothing to do with gengas, but I’m asking anyway.
I have a zetor 6748 that runs hot, there is water, where should I look for the fault?
I replaced the water pump 15-20 years ago and the cylinder head gasket a few years ago, but I suspect it’s one of these, unless the radiator is tight, but how do I find what the fault is?