Ok. heres the deal. I have a 59 GMC that we were boosting with the golf. it sat idleing and occasionally being reved to about 1500 2500 rpm. it was idleing for about 20 minutes and then i go to move it and notice theres anti-freeze on the ground. soi kill the engine and pop the hood again. It was overheating. So heres what i dont get: Why. It has a new thermostat that opened properly but we arent sure if the fans came on. any ideas?

 

Notice this is an old post, but will share my experience. Can be one of 3 possible things.

1. If you had drained the cooling system and filling up the system again, you need to bleed the system as there is air bubles in the system.

2. A faulty water pump can cause the overheating.

3. The head gasket has blown. When this has happened, the water channels on the cylinder head might be coroded as well and needs to be welded at an engineering place and the head needs to be skimmed again.

This is all I can think of.

 

Possible reason for overheating is a loose wire in the engine. Does your radiator fan turn on? One of the easiest ways to know whether the fan is the cause of the overheating is open the hood and look when the car is hot. Also you should be checking the level of the coolant and if there is any clog in the radiator. Better bring you the in the auto dealer to make sure they could see what is the real problem.

 

if you got coolant on the ground, that's one problem. Another overheating problem, especially if it's a golf, is the water pump.