Next would be a look around under the hood for anything obviously a problem such as coolant leak, sensor wiring frayed, disconnected or shorted. Most obvious is the coolant reservoir is not full.
Next, top off the coolant level and position this car on a lift. Because gravity is not a suggestion, it's the law. I'm going to pressure test the system and look for leaks. That will include looking in areas more easily seen from below. On starting the engine to move the car, I looked inside the reservoir for "turmoil". The car is not at engine temperature and has been sitting for hours so the thermostat should be closed. If I see coolant trying to come up out of that reservoir it is a sure sign of a bad head gasket. But it looks calm.
With the car on the ready to lift when needed I want to put pressure on the system. This a 16 psi system.
After several minutes the pressure has dropped slightly. I don't see any obvious leaks from the top and no drips underneath. Time to take a look from below after pumping it back to 16 psi.
Leaking from under a hose, at the clamp end. Actually the clamp is most accessible from above. The clamp was slightly loose. Now the leak is fixed. I don't know about the overheating though so not finished yet. It could have been overheating due to low coolant level but there could be other problems. I have to run the car, let the thermostat open and fill to level. The cooling fans run with A/C and I saw that working but the fans also are supposed to come on when coolant temperature gets around 220F. I've checked oil for coolant contamination and did a combustion gas test at the reservoir. The system is filled, the fans come on at 215F and off at 210F. Good circulation. No signs of overheating. Time for a road test.
Didn't see any problems from the cooling system on the road test. Customer called and said he was having boil-over and overheat at idle conditions but never at road speeds. I explained what I've found and done so far. He also said he has been working on the car and only added water to the cooling system. I need to test coolant strength after this cools enough. Then I'll give him a call back.
A few things while I'm waiting:
Water as a stand alone coolant is not good. It will cause rust and it has a lower boiling point than a 50/50 mix of water and antifreeze.
Flushing the cooling system is done as maintenance when changing coolant. If your radiator is plugged it will need replaced or removed and cleaned by rodding.
If you put a stopleak product in your cooling system, do it once. Don't keep doing it over and over and follow the directions. Mainly though, don't use a stopleak product.
The engine coolant tests as mostly water.
A few things while I'm waiting:
Water as a stand alone coolant is not good. It will cause rust and it has a lower boiling point than a 50/50 mix of water and antifreeze.
Flushing the cooling system is done as maintenance when changing coolant. If your radiator is plugged it will need replaced or removed and cleaned by rodding.
If you put a stopleak product in your cooling system, do it once. Don't keep doing it over and over and follow the directions. Mainly though, don't use a stopleak product.
The engine coolant tests as mostly water.
Drain and fill with a 50/50 mix and this car should be good to go.
Thanks for reading
Kenneth Hayes
G&G Auto Repair
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