My wierd coolant issue (97' 940 B230FK)

Hi there,

I have an issue with my coolant system, it doesn't overheat, not even with 40?C and AC running, but I think it gets too much pressure by touching the upper radiator hose after some either hard or long driving.

I suspect I have a small head gasket leak or crack, but coolant she only likes to drink about a glass of coolant every 5000km (3000miles) so its not major.

No oil on coolant or coolant on the oil pan, no signs of anything on the exhaust.

I blew the heater core hose in between the engine and the valve before the firewall, that's why my concerns.

Bought one of this co2 test liquids kits, and I have something going on cause there is air coming out of the coolant tank.

More on this, I opened the coolant cap slowly when hot, and let the coolant go back to its normal level, after letting it sit for 10 minutes, i started the car with the kit replacing the cap. Some air was comming as I said on idle, but the wierd thing is, after holding the car at 2000 rpm for 10 secs with no sign of air comming out of the test tube, and letting it go back to idle, the coolant started to overflow from the tank like crazy until I shut down the engine.

How come it does overflow like that when letting of and not on acceleration? It should be a massive headgasket leak if I'm seeing this? How do I follow? Can the car have such a coolant issue and run like nothing is wrong to the less mechanically inclined guy?

Btw the car is 335k Km and I have had it for the last 26k km in a year and a half.

Pull your plugs and inspect.

You probably need a headgasket.

A 97 is going to have a green or teal coolant cap on there. that is a high pressure system. With something slowly using coolant that could mean the combustion pressure which is a lot higher can go into the cooling system. Look at your spark plugs with your engine cooled down.

I have to agree with the above suggestion that the head gasket may need replacement.

Does the system hold pressure when cold - mine did as an early warning of head gasket failure. Excessive pressure when warm, radiator hoses still pressurised when cold.

pshnfry said:

Does the system hold pressure when cold - mine did as an early warning of head gasket failure. Excessive pressure when warm, radiator hoses still pressurised when cold.

Click to expand...

No it does not hold pressure when cold.

I'm gonna try to use the test kit starting the engine cold with the cap open and then check the cilinders while cooling from the sparkplugs with a small usb endoscope camera.

Well.. got the head out today after work, haven't inspected much but appart from some clogged passages doesn't look like much more.. have to inspect the head and block more and in detail with natural light

https://imgur.com/gallery/vrqvynC

The colour of piston #4 makes me think there is something different