300 TDI Cooling Issues

[Markb90]

1st post from a new member, forgive me if I have posted in the wrong section.

I have a 1995 Defender 90 300 TDI, it's done 185K but still happily soldiers on. I have a new problem this week in the water is getting forced out of the expansion tank cap. I've just bled the system, including raising the expansion tank and letting water out of the rad and thermostat bleed holes, plus a new expansion tank cap. This hasn't improved anything and as soon as I start the engine, from cold, water squirts at high pressure out of the new cap. I'm guessing there's a blockage somewhere and the full force of the Water Pump is going into the expansion tank, and most of what I've read suggests head gasket but I'm not sure I understand how that would create this scenario although this maybe optimistic thinking. One of the hoses out of the expansion tank splits into two via rubber connector, I think I've read that has a valve in it, is it possible that should be stopping the pump flow ? Thanks in advance, Mark

[crwoody]

Deffo sounds to me like a head gasket failure. They can fail in different places, between different chambers/cavities.

Yours sounds like it's failed between a combustion chamber and water jacket allowing combustion pressure into the the cooling system, the water pump doesn't really generate all that much pressure.

[Markb90]

39 minutes ago, crwoody said:

Deffo sounds to me like a head gasket failure. They can fail in different places, between different chambers/cavities.

Yours sounds like it's failed between a combustion chamber and water jacket allowing combustion pressure into the the cooling system, the water pump doesn't really generate all that much pressure.

Thank you, that all makes sense now as the water comes in regular surges that would match the rhythm of one piston at tick over.

Time to get it off and see what's what.