Can a bad Auxiliary Coolant pump create a boiling over and overheating situation. Half of the blogs say yes, half say no.

I believe that all cooling systems need circulation and anything that hinders that can create an overheating problem. Any commentary would be helpful.

Rob
XJ8 VDP 2004
ex: XJ6 1996

 

I don't think so. The engine cooling system is so simple in nature, only a few things can make it go wrong, such as a bad thermostat, worn water pump, loose fan belt, bad electric fan switch, incorrect antifreeze mixture, retarded ignition, clogged radiator or God forbid, a poorly designed cooling system. The aux water pump is to force more coolant through the heater core to heat the inside of the car more efficiently since this is a secondary passageway. But they only put aux water pumps in luxury cars.

 

Thanks XJR,

Thats what half the blogs say. My replacement pump seems to have fixed the problem. I have replaced the thermostat, thermostat housing, radiator cap and waterpump. It still boiled over until I changed the auxiliary pump. I have driven about 65 miles and she has been fine (so far). I'm wondering if this bad pump created air pockets, which are a big evil to these systems. Im hoping sharing this info will shed some light on this and also help others.

Rob
XJ8 VDP 2004
EX-XJ6 1996

 

BTW, I think you have an X350. Different sub forum. But the info most likely still applies.