Where is my coolant going????

[Patrol GQ]

Hi Guy’s,
I have a 1991 GQ Patrol 4.2 litre petrol.
I have to keep topping up the coolant regularly, but cannot find any leaks in the cooling system anywhere. It is as frustrating as all hell. Can anyone give me any clues as to what is going on.
It is not getting hot. It runs perfectly okay, it does not miss. There is no coolant in the oil. It is not burning coolant. Nothing appears to be wrong anywhere.

I would be grateful for any suggestions.
thanks Geoff

[garrett]

check the welsh plugs, my old mav used to leak from there but i never noticed as it was jst a tiny trickle

[Bulbous]

This is going to sound a bit odd, but check the radiator.

Few years back had a BMW 325i that was losing coolant. Turned out that there was a bad seam on the radiator. The amazing thing was that

1. When the engine was cold, it didn't leak.
2. When the engine was hot, it didn't leak.

It only leaked for a short period of time while the engine was warming up, but after a few starts it was enough to activate the low coolant light.

Only found it when I went for a short enough trip to just warm it up a bit. That's when I could see it pouring out.

[WayneUH-1]

I had the exact same problem up until 2 weeks ago. In my case I had installed some thermo fans and the thermostat goes into the top radiator pipe and seemed like a good seal but I was using 100% water in the radiator and there was a tiny leak that evaporated straight away so no sign of the leak. I changed the water for green antifreeze and sure enough you could see the trail of green stain down the side of the radiator. I re sealed it and put and extra metal clamp around it and now no problem.

[taslucas]

Also have a look at the overflow bottle. Mine was cracked and perished(above the "high" mark) and as the engine cooled, the fluid went out of the overflow tube (to drain onto the ground) instead of going back into the overflow bottle. I siliconed it up and it was all good:)

[97_gq_lwb]

A backyard pressure test might help just put air into the overflow line you could even use an old valve and do it at a servo if you don't have a pump.
Just pump it up to the rated pressure on the cap and then look for leaks.

[OOHA]

Just worth checking had same thing on mine wesh plug at back of the head hard 2 c only leaked on cool down
coolant runs down just b 4 gear box .