I noticed I was losing coolant a while ago and I thought I figured it out. The radiator drain had a small leak and I figured that was the source of the problem. Replaced the drain and that leak stopped.

I recently went on a LONG drive (6 hours) and just before I reached my destination I noticed the temps shot up from 185 to 210. I was within a few miles of where I was going so I stopped twice to let it cool down and limped it there. Once the engine had cooled down I noticed I had lost a little over half a gallon of coolant. I bought another gallon of coolant and on the way back I stopped about halfway (3 hours) and let the engine cool down enough to add more coolant. I had lost almost 1/4 to 1/3 of a gallon and made it home without any issues. This was a lot of driving at 60mph with the 4 spd.

I cannot see any leaks after I drive it, or notice anything when I've parked it. Could it be something as simple as a bad rad cap? There doesn't seem to be any white smoke or anything unusual from the exhaust but I guess it could also be the start of a bad head gasket?

Any advice?

 

An old trick, and not always useful, is to see if the coolant system is sealed. Either some homebrew version of a hand pump to pressurize the radiator or using an inflated glove or balloon over the radiator fill tube. The idea being that if there is a leak, it will drop pressure/balloon will deflate and you might be able to hear it. Leaks can come from many places. Don't use shop air to do this. It's not intended for that high of pressure.

 

The original motor that was in my truck had the same issue, but much faster. No blown headgasket but loss of coolant and overheating. It turned out i had a crack in my head from the coolant channel into the combustion chamber. There wasnt enough coolant burning to give white exhaust or get into the oil, but it was burning nonetheless. After a long drive, i would release the lever on my radiator cap and it would expel nothing but steam for a solid 5 mins due to the combustion entering the cooling system.

 

I'll definitely try something like this to see if there is some kind of leak.

 

Is this something that can be repaired? Thankfully at the moment it's not that bad. I do have a 22R that I've been considering swapping in. Maybe now is the time to get that engine refreshed and ready to drop in.

 

That to a shop & have them stick the smog checker probe into the radiator filler neck, if hydrocarbons in the coolant, it is a brown head gasket!