01 XJ no heat

GotWood

GotWood

Sayer of Fact
Joined
Jan 12, 2007
Location
Maiden, NC
My daughter's XJ has very poor heat. I've flushed the core but no real difference. My question is (@Jody Treadway) why does the temp gauge never get near 200°? She can drive 30 min and barely reach 140°. Is this a symptom of poor water flow because of a bad core?
 
Sounds like the thermostat is stuck open, if you can trust what the temp gauge is telling you. If the core was bad (assuming your talking about the main rad core?), you'd have overheating problems and not problems reaching operating temperature.
 
See if each heater hoses feels the same in terms of temperature. Different temps indicate lack of flow. If each heater hose is hot, you should have heat inside.
It may be a simple case of a bad thermostat. If it's stuck open, you'll have similar symptoms.
 
Fabrik8 said:
Sounds like the thermostat is stuck open, if you can trust what the temp gauge is telling you. If the core was bad (assuming your talking about the main rad core?), you'd have overheating problems and not problems reaching operating temperature.
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I was assuming heater core. Has new radiator.
 
GotWood said:
I was assuming heater core. Has new radiator.
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Sounds like the lack of heat is just mirroring the problem getting up to engine operating temperature. Lack of heater core flow would obviously make that worse, but if it is actually not getting above 140degF for a long time, that's going to be all/most of your problem with lack of heat. You're not going to notice a stuck open thermostat as much at high ambient temps, because it spends so much time being open, but in low winter ambient temps it spends a lot more time doing temperature regulation so that's when you see problems with not getting up to temp if it's stuck open, etc. Virtually every other cooling system problem will cause overheating, and there's very few things that can cause over-cooling.
 
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Are you sure it has a thermostat at all? Sounds like someone may have removed it.
 
Do you have a inferred thermometer? You could shoot the theromstate housing and see actual temps.


Or you could just hit it with your purse.
 
Could be the coolant is low.. since it's a new radiator and all. Might be worth it to check.

Hi, I'm new
 
scrubber3 said:
Could be the coolant is low.. since it's a new radiator and all. Might be worth it to check.

Hi, I'm new
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Funny you say that as common sense would say, "if it's low on coolant it would over heat". However, I bought a WJ once that had a terrible coolant leak at the time of purchase (I was unaware). I drove it home and the temp gauge never read above 100*. Got home, saw the radiator was empty and filled it. Ran it and the temp gauge read 200*. I promptly found the leak and fixed it. I thought it was odd that lack of coolant would cause the temp sensor to read low but now I know it's possible.
 
adamk said:
Funny you say that as common sense would say, "if it's low on coolant it would over heat". However, I bought a WJ once that had a terrible coolant leak at the time of purchase (I was unaware). I drove it home and the temp gauge never read above 100*. Got home, saw the radiator was empty and filled it. Ran it and the temp gauge read 200*. I promptly found the leak and fixed it. I thought it was odd that lack of coolant would cause the temp sensor to read low but now I know it's possible.
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Yeah that happens often, it’s due to a lack of circulation and therefore the sending unit is not getting water to it for an accurate reading.
 
It does read something, but it’s reading the air and steam which makes in innacurate. I’ve actually watched the temp gauge jump around once the water starting getting to it. You figure if water is boiling at 232* then the steam rising off that water is cooling rapidly and not reading anywhere near the same.

Steam is a big killer for a radiator. Low coolant will cause it to build steam and blow out hoses, plastic radiator tanks, head gaskets and caps.
 
77GreenMachine said:
It does read something, but it’s reading the air and steam which makes in innacurate. I’ve actually watched the temp gauge jump around once the water starting getting to it. You figure if water is boiling at 232* then the steam rising off that water is cooling rapidly and not reading anywhere near the same.

Steam is a big killer for a radiator. Low coolant will cause it to build steam and blow out hoses, plastic radiator tanks, head gaskets and caps.
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212°
 
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