Newbie with overheating jimny

Thanks ill try that next, fan could be suspect, rads arent to expensive either so may just change it anyway.

If the heater cools the engine down then it suggests there is not enough water flowing through the radiator. Apart from what has already been mentioned it could be:

Head gasket - is the water dirty, the oil emulsified or one of the spark plugs very clean?

Water pump - is it turning correctly, is the belt slipping, can you turn the water pump b6 hand?

Thermostat not opening - not sure how you test this without taking it out.

If you are not loosing water, the oil is clean and the spark plugs normal, then it’s just use low flow. If the rad s clean and all of the pipes good then check the water pump after that it is most likely the thermostat.

Thanks next chance i get ill check, got a water pump, may fit that at some point just to elliminate, are they easy to fit?

so far theres no sign its the head gasket , plugs are clean no mayonaise anywhere

by clean i mean dirty haha