water problem

I have a 79000 mile P38 V8 which has started to boil in traffic so I changed the thermostat..still boiled so the gurus said it'll be a blocked radiator changed that still boiled so the gurus said it'll be that cheap thermostat you bought,get a genuine one....it still boils but it goes on all eight and there is no gasket problem.Even tried a water pump as the rad doesn't seem to get hot,but no improvement, any ideas please ?

Was the radiator a new one or secondhand one? Does it only boil when stuck in traffic? Assuming that the rad, water pump and thermostat are new and that it only does it while static I would say that your fan is at fault. If it's a viscous fan it aint locking up when it gets hot. If it's an electric fan then it aint kicking in.

Is the top hose to the radiator getting hot? What about the bottom hose? Is that getting hot? warm? or staying cold? If it's staying cold then you have a circulation problem.

Have you checked all your hoses?
I thought my head gasket had gone; had similar symptoms to what you describe (mines a leccy fan)

Do you appear to be losing/using water?

I changed the (boiled) stat, and once the water was circulating at temp, it showed up a split hose from the heater matrix; £2.50 for a bit of hose Vs hassle and cost of head gasket: SORTED


**Edititititititited to add, I saw the steam in the dark, in the torchlight, so it may be worth running her up to temp in the dark and use a torch and see if you can see anything!

Thanks all,it does it when in traffic or driving in town and the rad is not getting hot so I changed the water pump for a new one but it didn't seem to help....and yes the new rad was new.The top hose does get hot but not the rad except for the corner where the th enters.With no guts in the thermostat housing it ran for 1 month without losing any water but of course it ran cool.The towing season starts in two weeks so more ideas please. Ta J.P.

Sounds like you have an airlock or blockage either in the radiator, or more likely from the sound of it, in the engine/cooling system elsewhere ..

I'd take the hoses off the radiator and drain the system, flush the radiator with a household hosepipe to be sure it's clear, then try the same with the engine .. I've done it with success before with an engine running so it cleans out the pump etc, not, I hasten to add, a V8, but it appears you have little to lose.

Big trouble is it really could still be a simple leak, split hoses normally, but it's getting hot and escaping as steam, as mentioned above, and you simply can't see it.