Citroen Relay Coolant over pressurising

[Ellerocco]

Hello!
Hoping someone can help answer this conundrum.

First thing is first - The van runs brilliantly and has never overheated.

Initially i was having trouble with the coolant system overpressurising - even with the engine cold, when I removed the radiator cap it would burst out and overflow.

Tested for exhaust gases, overall an inconclusive test but 2 mechanics who also did the test didn't think it was the head gasket. The EGR valve and cooler was bypassed in case it was that.

We have changed the thermostat today as the old one was shut closed when testing.
Flushed the coolant system and have filled it with new stuff, but only 5L or so has gone in (11.5L capacity) and after idling and getting up to temperature, plus a 20 minute drive, the radiator expansion tank is full with no signs of coolant in the top radiator hose... I have bled it using the bleed screw.

The temperature gauge gets up to half way and sits there, although on the last drive it would dip ever so slightly then get back to temperature.

It has NEVER overheated and runs brilliantly.

But why isn't the coolant circulating?! Could be the water pump or a blocked radiator - but it's strange that it's not overheating and runs so well?

And advice on how to check those would be appreciated or any ideas in general!

Thank you!

[PaulC5]

Could be the water pump, was it replaced when the timing belt was changed ?

[Ben*17]

Hi,
Did you find out what was actually going on with your van?

I'm having very similar symptoms on my relay.

It's driving me mad.

Really hope that you can help.