3.4 Over Heating

[Oldsmobile Doctor]

I had someone last night asking me over the phone about there Oldsmobile overheating. It is mid 90's with a 4.3 Quad-4 in it. When they drive it with the heater on it over heats. When they drive it with the heater off it is ok. I haven't looked at the car personally and can't see how it could be doing that. Maybe the other way around.

Thanks....

[xeroinfinity]

The heater core is part of the cooling system so if the cores clogged could be why its over heating when off.

Has anyone checkked the heater lines while the engines warmed up to see if they are hot or cold ?
Or if you can tell whether warm/hotcoolant is moving thru the lines when the engines running?

[Oldsmobile Doctor]

They say that the heater is working and it over heats when they use the heater

[razr_88]

i would say then that radiator is partially plugged so that when the heater is turned on most of the water gets routed through the heater core, bypassing the radiator and causing overheating. If the car has worked well in the past with the heater turned on, then I would suspect a partially plugged radiator. take xeroinfinity's advice and feel for hoses that are hotter/colder than they should be

[Oldsmobile Doctor]

Thanks, they never got past the asking about stage..