95 S, 4.3, intake manifold coolant leak into the engine, small amount of water in the oil.

Removed the radiator cap, drilled a small hole in the inner seal and seat to allow the system to run at near zero pressure. Also added Bars Head gasket stop leak. Set the coolant level to just below full at operating temperature.

​​​​​​The excess water out the exhaust has stopped. No overheating.

Also had a problem with temperature swings, drilled a small bypass hole in the thermostat plate to prevent air from being trapped under the thermostat which keeps it from opening.

 

Good info! What temp do you run at?

 

It is very possible you are due for replacing the lower intake manifold (LIM)gaskets. There are several threads on this.