My 94 seville sts overheats. Ive checked for blown head gasket,they are good water pump is good, radiator is not plugged and I have even tried to bypass the heater core it still overheats. the top radiator hose gets wicked hot but lower doesnt get hot,the thermostat is new. does anybody have any other suggestions.



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My 94 seville sts overheats. Ive checked for blown head gasket,they are good water pump is good, radiator is not plugged and I have even tried to bypass the heater core it still overheats. the top radiator hose gets wicked hot but lower doesnt get hot,the thermostat is new. does anybody have any other suggestions.

by your description, coolant is NOT FLOWING.
pull the stat and see how she runs then.

where did you get the PUMP ?

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The pump was replaced at caddy dealer just before i bought the car. Ill try without the t stat, i take it the housing wont leak without the t stat.

The pump was replaced at caddy dealer just before i bought the car. Ill try without the t stat, i take it the housing wont leak without the t stat.

just keep in mind that if the top hose is really hot and the bottom hose is not, the issue is FLOW, of lack of it.


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Ok I tried removing the t stat and still the same. i bypassed the heater core and just left the the hoses going to the core wide open and no water came out of them when running, but the car still got hot.Could the head gasket have failed even more since it was first tested or is there anything else i should try.Prior to all this the car always ran at 199 moving and 200-220 at a stop, then one day at a stop the temp climed to 240 then i shut it off.

Ok I tried removing the t stat and still the same. i bypassed the heater core and just left the the hoses going to the core wide open and no water came out of them when running, but the car still got hot.Could the head gasket have failed even more since it was first tested or is there anything else i should try.Prior to all this the car always ran at 199 moving and 200-220 at a stop, then one day at a stop the temp climed to 240 then i shut it off.

stat is still off ?
pull the top hose and run the engine .. if coolant does not come out like a geyser, your pump is either dead of defective.

not sure if you can tell that at the heater core but you will know for sure at the rad side.



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it doesnt come out like a geyser it just kind of flows out

stat is stll off

it doesnt come out like a geyser it just kind of flows out

if you rev the engine, coolant should jump out if the stat is OFF and water pump is good.




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ok so fari have i have done everything and it all looks normal, but the water pump looks like its not flowing enough water so i put everything back the way it should be but broke a bolt off in the thermostat housing so im taking a break from the car for a day thanks again for all the help

ok so fari have i have done everything and it all looks normal, but the water pump looks like its not flowing enough water so i put everything back the way it should be but broke a bolt off in the thermostat housing so im taking a break from the car for a day thanks again for all the help


water pumps have been known to be defective, even impellers installed backwards at the factory.
Although it is unusual, an improper water pump gasket installation or use of RTV/silicone at the water pump can and will restrict flow out of the pump. just cuz the pump is a dealer installation is no guarantee that it was done correctly.

also, a system blockage may be at play here.

if the headgasket had failed, and all else was OK, both the top and bottom hoses would be just as over heated. By your description of hot upper hose and colder bottom hose, I say this is not an issue.
engine seems to be overheating due to lack of coolant flow.

assuming all your descriptions in the thread are correct, I would be doing a reverse flush, and removing and inspecting the pump. Once the stat is removed and radiator is verified not blocked, there should be nothing to prevent or restrict flow. It is a simple system that simply moves coolant from engine to radiator and back.



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Ok I have flushed the system and have found the heater core is definatly blocked, with the core bypassed top and bottom hose get hot.The car still overheats, there is no leak and i cant see water in the oil,it overheats faster if its driving.With the top hose off water flows out, does it sound like a headgasket, the temp climbs very quick.

With a garden hose in the top hose water flows out the bottom hose. If the stat is out it seems to get hot quicker but could just be me.Should the water in the fill tank be pulsating up and down once the stat opens and when it does this it flows out of the tank. how can i tell if the impellers are installed wrong

top hose, bottom hose .. which ones?

I think we have a lot of confusion here between radiator hoses and heater hoses and whatever other hoses.

please clarify


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radiator hoses

With a garden hose in the top hose water flows out the bottom hose. If the stat is out it seems to get hot quicker but could just be me.Should the water in the fill tank be pulsating up and down once the stat opens and when it does this it flows out of the tank. how can i tell if the impellers are installed wrong

first item tells me that system is clear of obstructions

2nd item .. job of stat is to stop coolant from going to radiator if engine coolant is too cold. W/O it, warm coolant goes straight to the radiator.

3rd item .. compare to a known good pump or go to a different supplier and ask to see one of their pumps .. different supplier should be a different batch.