Hi I've got a peugoet expert van which keeps chucking its coolant out the header tank cap.

I've had a look at it myself and changed the header tank and cap but it still doing the same.

I can leave the van to idle all day with the cap off and the temp never goes above half way if i put a weight on the accelerator still with no cap on then the temp will go up to around half way then the fans kick in and the temp goes back down and the coolant never moves.
Then i put the cap back on and drive it the temp gauge stays bellow half and the heaters are nice and hot.
Pull over have a look and coolant all over the header tank.

I've put a coolant pressure tester kit on and left it on for around half an hour and no loss of fluid.

Has anyone got any other ideas?

Cheers Bram

 

ok its a bit of a guess but a sticky thermostat could cause this as it is not opening and closing when it should so bits of engine can boil cooling fluid and cause big presure under load!

 

I thought about the that but when i felt all the pipes around the engine they are all hot so thought the coolant must be flowing around the engine.

I might just change it anyway.

Thanks

 

Could be anything from an airlock somewhere, to a head gasket issue.

Try draining the entire system, or as best you can, then refill to manufacturers listed capacity. If you get the full amount in you can rule out air locks. If you fall far short, then you can be sure there is air trapped somewhere.

Are there any bleed points on any hoses ?

 

Sounds like a head gasket issue or crack, allowing the push of air into the cooling system as cylinder pressure increases

 

Sniff test. Will either rule out or prove a combustion gas leak problem be it either head gasket or a crack somewhere.