OK, I have this problem, my Classic recently blew its headgasket, long story short, it dropped a cyl liner, so I found a used engine out of a running 1995 Classic, perfect even compression no leaks etc.. 70k miles. I installed the engine, I replaced, head gaskets, water pump, all hoses, new thermostat, fan clutch, all sensors on engine, new belts, I swear I left nothing unchanged. Here is my issue, I fill the cooling system up, I thnk I get all the air out, the RR does not over heat, yes I replace the temp sensor, but the water boils somewhere and it bbuilds up pressure, and burps its out, after that still runs cool, but it builds up lots of steam. I presuure checked my head gasket, they are good, it does not build up that kind of pressure, only when hot.

Do I have an air bubble in the system?

 

You didn't mention anything about the radiator. Classics will develop seepage at the side tanks ---down at the bottom. Use a bright flashlight, and look for evidence of leakage at the bottom of the fan shroud where the core meets the tank. Over time, this allows air to enter the system with the symptoms you describe. Also --- we have seen Land Rovers come in with blown engines that the owner thought was due to the head gaskets going, but that was only one part of the "cause and effect" relationship. The radiator was clogged internally, and was the root cause.

regards,

Geoman
www.eurotekapg.com

 

Thanks for your response, however the radiator is brand new

 

Found my problem, The new water pump that I installed has the inpeller installed backwards. So hopefully I have ruined another engine, so far it looks good, but time will tell.