Sorry if this rambles I’m trying to work where to start, and how to explain, I have in another thread a minor drop in water in my overflow tank, every 500 to 1000 k I top up,
this week I checked and no visible water in the tank, usually I think I mean think , as I’m not sure , when i unscrew the cap it bubbles up and then has a increased level in the tank that’s ok.
this time it didn’t bubble up I added 500 mil to fill it a third of the way up the tank, today checked it and added 500 mills again, still no bubble up.
What do I check first the cap ?
i can’t see water under the car
the ultragauge shows temp between 199 208 depending if around town or open road

 

You have a leak
do a pressure test on your cooling system there is kits you can buy.
Hopefully it’s not getting burned off due to head gaskets leaks if you can’t see it on the floor

 

Thanks took it to the shop they did a pressure test 20psi for 40 min , with no loss of pressure, they think it may be the overflow cap, cheap at 20 bucks if that’s the fault.
will go for a drive on the weekend and see

 

if it’s the overflow cap it would be very easy to tell. Or test

you may have a leak when things start to heat up and expanding
hopefully it’s not the head gasket.

 

It is not the cap, I know because I run all mine one turn loose and don’t lose any coolant. Truck is likely drinking it sorry to say, how many miles since a hg job?

 

Just to be sure, check your throttle heater for a leak. Sounding like a HG. Check your oil dipstick, and oil cap for signs of coolant (milkshake oil bad, excessive moisture on cap, bad sign).

 

Put a bottle on the overflow line from the expansion bottle, when my head gasket started to go it over pressured just enough to dump some coolant out the overflow line. I only noticed it when I moved the line when doing some work so it dumped forward.

You might need some fuel line to extend, I had no overheat, the combustion gas test, was marginal , no milkshake under the cap and no excess white smoke.

 

Checked the dipstick and cap both seem ok, I’ll take it for a spin tomorrow and check again