Reader Question: I have a 1995 Chevy truck that runs great but I think it has a coolant leak, because its overflow box is always empty. I frequently stop in at Kwik Lube to have my water level checked, and they always add coolant to my overflow box.
They have done a pressure test to try to find the leak, but we cannot seem to find it. It is losing pressure at 11.5 lbs. My cap is 15 lbs pressure. Its water level slowly drops over time, but it never run hot according to its gauge. However, the gauge does strange things while I am driving. It drops and rises, but never rises above 210. It will do this the whole time I am out on the road.
I asked the mechanic at the shop if it was the thermostat, but he didn’t seem to think so. I changed the water pump and thermostat out just this past year because the water pump was leaking. So he feels truck’s thermostat is too new I guess to be faulty.
Also, I never see water under my truck. Now just recently, I am seeing steam come from the front of my truck when either I stop and kill the engine, steam or smoke I am not sure.
Please give me some ideas to check out. Oh, I am a female who does not know much about engines, but before going in to a shop I like being informed.
If you recently had a cooling system pressure test and there were no signs on an internal or external coolant leak that is a good sign. Those plastic overflow bottles are notorious for leaking, so check the bottle itself for leaks, especially around the seams and the bottom of the bottle. What you should be concerned with is the coolant level inside the radiator itself more than the coolant level in the overflow bottle.
If you are consistently adding coolant to the radiator, you probably DO have a small coolant leak and the cooling system pressure test should be done again. The smoke you see could be from a coolant leak spraying coolant on the hot engine, or it could be from a small engine oil leak that is leaking oil onto the hot engine. I would pop the hood, look at where the smoke is coming from, and see if you can see any green coolant somewhere on the engine.
The temperature gauge can fluctuate a little during stop in go traffic and while on the freeway. If the movement you see is slight and you do not have a coolant leak, you can try replacing the thermostat and see if it helps or you can just leave the situation alone. 1992-95 Chevy truck dash gauges seem to fluctuate and not be as accurate as other model years for some reason anyway.
If a small internal coolant leak is found, and they suspect something like a leaking head gasket as the culprit you might want to try a can of K&W Engine Block Seal additive before you invest big bucks in internal engine repairs.
Here is more about this product.