Loosing coolant

[Tractionman]

EDIT. That should read underside of the top of header tank, I.e.the cap.

 

[Steveindar]

They always say problems come in three's. Well a little trip to town, 150km's away, and the heater pipe coming out of the block on left side sprung a leak. I thought this might be the larger problem. I made a marifa plan and blocked off the entire heater circuit. Next issue was an apparent slow puncture which transmoglified into an instant flat at the most inconvenient place in town, a roundabout.
So no nearer and still loosing coolant. There has to be a pressure buildup somewhere within the rev range pushing coolant into the overflow bottle but not allowing it to suck back as the coolant cools. I'll find another cap today, but I'm still leaning towards a head strip and new gasket.

 

[MisterCruiser]

Some movement of coolant in the rad is normal, with vibration and the water pump working.
I am not familiar with yours, but does it have a rubber hose fixed to the underside of the header tank( overflow bottle). If so, check it hasn't dropped off. If it has, when there is expansion in the coolant, excess is pumped out of radiator into the bottle, when system is cooling that excess is then sucked back into the system.
If there is a pipe and it's fell off, coolant will continue to fill the bottle, but not suck it back up

Is there 2 separate pipes connecting between the rad and the expansion bottle on the 80 series? There's only 1 on my 90 series which fills the bottle and sucks it back, if it fell off, the bottle won't still get filled. Is the 80 series different, I'd have thought it strange to have 2 separate hoses for fill / suck back.

 

[Grimbo]

Is there 2 separate pipes connecting between the rad and the expansion bottle on the 80 series? There's only 1 on my 90 series which fills the bottle and sucks it back, if it fell off, the bottle won't still get filled. Is the 80 series different, I'd have thought it strange to have 2 separate hoses for fill / suck back.

No just the one.....

 

[Michael80]

Hi Steve,
Just an idea, Is your vehicle manual or auto? You could be losing it into the auto gearbox from the radiator? Is your autobox level ok?
You can normally pressure test the radiator cap with the coolant pressure tester? I would pressure test the system cold and have a small bottle of leak detector if you suspect the fittings are leaking. 1 psi in 10mins is too much.
Could also try getting the levels correct and then take the vehicle for a drive until its up to temperature, whilst stoppedwith the engine still running place the radiator leak off pipe in to a clear bottle with some water in it and watch for bubbles with the engine running, a milk bottle is good for this. This will show you if your head gasket is causing the problem as you will have a small but steady flow of bubbles.

 

[frank rabbets]

Good idea Michael. Dry mouth test. Horrible but good luck Steve and let us know.