cooling issues

[zrx-fighter]

after some info on why my cooling system is not working properly.
transplanted engine into a p100 pickup using an aluminum radiator and electric fans, also plumbed in a volvo 440 header tank. put new cam belt and new water pump. just some back ground info.
The issue, start and run engine on tick over or rev occasionally the temp rises the cab heater warms up and works nicely. after so long the engine gets up to 95 degress, so i turn on the fans to cool down the radiator cools down great but the engine temp just keeps rising and does not drop. as you look at the engine the hose that runs from the thermostat goes to the bottom of the radiator never seems to get that warm but the other that goes to the top of the rad gets realy hot. i do have a new thermostat in it it does work as have two brand new ones as thought the first one faulty and checked the other works.
Any one got any idea what the problem is as the car is almost finished and need this sorted before i can put on the road.
Thanks all in advance

 

[Bushwhacker]

I think the problem is the header tank.
Does it have a pressure cap or is the cap on the radiator?

I delete the header tanks from the cooling systems and use a radiator with a pressure cap and overflow spout that goes to an expansion tank and a 16" electric fan. Never had any cooling issues.

 

[Zuffen]

Interesting I've always run a pressurised header tank without a separate pressure cap on the radiator.

Never had a problem even when running 21psi of boost.

Have you checked the radiator isn't blocked?

If the top hose is heating up it tells us the waterpump is circulating water.

I feel you need to look at why the hot water isn't going into or through the bottom hose as a first priority and work from there.

As an afterthought I'd try removing the bottom hose from the radiator and using a long pipe get it up above the engine and see if the waterpump will pump water out the end of the pipe. This will tell you if the waterpump is pumping with sufficient force to get the water through the radiator.

I'd also feed the engine water from a hose to stop it overheating.