Air Lock? Head Gasket? Help please

Hi there, I am wondering if anyone can help me out as I am stumped..... I have a 1995 discovery with a 300tdi fitted and it is doing a strange thing.

When I set off for work it is obviously cold and I get no heat from the heater blowers, the temp gauge rises to just below the red and the comes back to half way(normal running temp) and the heater then blows hot air. I have replaced the radiator, thermostat and head gasket if that helps. It also seems like the cooling system is pressurising as the water pipes are going hard but not solid.

Any ideas greatly appreciated before I take the head off and replace it as I am suspecting a crack in the current one?

Thanks

check rad when engine hot its hot all over ,remove bungs one from thermostat housing and other on rad fill system till they overflow and replace ,overfilling expansion tank wont hurt, if you look down the back of water pump housing youll see if p gasket is leaking

Thanks for the reply, I have already taken the bungs out as you suggested but it is still doing it. I will have a look to see if the P gasket is leaking, I guess if it is then it will be obvious?

when you removed bungs did coolant spill out ,system needs to be completely full ,sounds like yours isnt and water pump is having to fill heater matrix ,which could be leak ,poor filling,or pressure,

Thanks again, I will check the P gasket in the morning but it does not seem to be losing any coolant. It makes sense what you are saying, would this also cause the system to pressurise?

I had exactly the same thing happen to my Defender 90 300tdi last year.

I had my radiator go and subsequently blew the head gasket previously. I bought a new head gasket off flea bay and had the head skimmed and the gasket fitted, along with new radiator.

Some months later it started doing exactly what yours is doing, tried all sorts including replacing thermostat, coolant reservoir cap but it got progressively worse and eventually it caused the engine to heat seize.

Turned out the head gasket had gone again..........possibly cheap, inferior quality gasket. Second head skim and new gasket (good quality one) now it's fine!

Kev

Thanks for the reply Kev. I thought it was probably going to involve taking the head off again.

its only worth using genuine Ellring head gaskets !