Hey all.. I recently picked up an 89 Trooper for cheap.. I knew there'd be some issues.. just trying to figure em all out now

So, its loosing some coolant somewhere. There's no visible leaks and it doesnÆt seem to be the head gasket (I was told it was replaced 3 years ago) and the heater will work intermittently. Blowing hot for a while, then cold, then it starts blowing hot again.. And the temp gauge is a bit erratic staying a little blow half for a while then jumping up to above half for a while and going back down. This will happen while its idling with the radiator cap off making sure its topped off and while driving. So I thought maybe the previous owner put a bunch of stop leak gunk in there so I had the radiator flushed. DoesnÆt seem to have done much.

Im wondering if a bad thermostat might cause something like this? I was going to try that. If that doesnÆt do anything I not sure what to do other than replace the radiator.

Any thoughts or suggestions?


Thanks