Coolant loss from overflow tank and overheating

[hayden]

Hey guys, a mate of mine has a 1998 Holden VT Commodore and it would always overheat. He through heaps of new parts at it to try fix it, a new thermostat, radiator cap and a waterpump. He couldnt fix it. He got me to look at it and it was running rough, lots of white smoke from the exhaust and the oil was full of coolant. I pulled his engine apart and replaced his head gaskets. I inspected the heads and block for cracks and warps etc and everything was fine. I put the car back together and changed the oil a few times to get the coolant out and all that. After that his car was running great, everything was fine. About 50ks of driving later he bought it back to me saying it dropped about 5 litres of water from the overflow. He also said that the heat gauge went to hot and then just dropped really quick back to normal temperature. I thought maybe air in the system but im sure i bled it properly. He got it to my house, i opened the hood and noticed a small hissing noise coming from near the radiator. Could a small crack in the radiator or a small leak in the hose make it drop 5 litres of coolant from the overflow? Help is appreciated, im sick of working on this car and he has had enough from all the stress its causing. Thermo fans, waterpump, thermostat all that is fine.

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[george gonzalez]

It could be the head gasket again.

What I’ve done once on a car that wasn’t worth redoing the whole head thing again, I took off the valve cover and cranked on the head bolts again, with another 20% more torque than spec. I had nothing to lose at that point. The car worked fine for two years after that when I sold it and the new owner hasn’t complained about any problems so it probably held for quite a while.

[Donnie Lerch]

I’m running into the same thing with my truck. There isn’t any coolant in the oil or anything of the sort, I’m just losing several liters of coolant from the overflow tank, somewhat quickly. I’ve replaced all the hoses going to and from the radiator, coolant reservoir, and water pump except one in a rather hard area to reach, so I guess that’s the leaking hose. Anyways, have you tried replacing all the hoses? It might not fix it completely, but it’s easier than tearing apart the engine and redoing the head gaskets. I’d try that first.

[Austin]

Don’t throw any more parts at it. The first thing you need to do is a pressure test. Find out if it’s leaking. Then do a block test, I would assume you put new head bolts in when you did the gaskets, but if not that could be your problem.

[hayden]

i presure tested the radiator and it spray a lot of coolant.it has a big hole in it would that be why it overheats

[Bill]

If there is a leak in the rad you not only lose coolant but the system will not pressurize properly. If there is no coolant in the oil I suspect a replacement radiator should cure the problem.

The rad needs to be replaced anyway no matter what else has failed.

[Author]

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