So I bought a 94 4runner for 300$ from someone who never got around to doing a head gasket change. So me and my buddy did. Took it apart put new injectors/cups, spark plugs, spark wires, and the head and various gaskets. We got it back together and it's running but now only runs for a few minutes until it overheats. I put a new thermostat and radiator and still same problem. Then checked the waterpump and it looks fine. I'm at a loss of what to do now. I've put too much to scrap it but I also don't want it to cost a great deal of time or money. If anyone has any suggestions that would be very helpful.

 

The problem is likely not a true overheat condition. It's probably due to not getting the cooling system filled correctly. So my questions to help diagnose that are:

1. Are you able to get the entire 10.6 quarts, required to fill it, in the system before it appears to be full?

2. Have you confirmed that by measuring the amount of coolant as you are filling it, or have the coolant premeasured in containers prior to filling?

3. Have you double checked that by measuring the amount that can be drained from the system? It won't be the entire 10.6 quarts. Since you can't drain the heater core. And it can be hard to get the block fully drained, and what of it you can, is tricky to contain without spillage. Much less measure the amount.

4. What goes in and what comes out should be more than 2 gallons. How close are you to that amount?