Heater core/water pump help!

Hi Gang,

I did some searching and couldn't find an answer so I thought some of you fine folks would help me out...

Driving from Florida to New York in my 99 XJ I noticed that I did not have temp control. This was with the AC on or off, I just could not get any heat. I checked the blend door and motor, both working fine. In checking under the hood, I noticed that the that the heater hose from the water pump was not up to temp like the other one. I took a look at my FSM and noticed that on page 7-2 it states that "A quick test for the water pump is to see if the heater warms properly". Can any one tell me of test procedures for both the heater core and the water pump so that I can properly diagnose my problem?

Many Thanks

Well, here are a couple of quick things you can check. First, with the engine running, does the radiator get hot? Do both upper and lower radiator hoses get hot? If yes, the water pump is pumping. If not your water pump is suspect.....you could also have a clogged rad. Do the same for your heater core. Check both hoses to see if they are hot. If not the core could be clogged. I'm sure your engine comes up to temp and you run around 200 deg. Check on those thinhs and let us know.

jeepcj/jeepxj said:

Well, here are a couple of quick things you can check. First, with the engine running, does the radiator get hot? Do both upper and lower radiator hoses get hot? If yes, the water pump is pumping. If not your water pump is suspect.....you could also have a clogged rad. Do the same for your heater core. Check both hoses to see if they are hot. If not the core could be clogged. I'm sure your engine comes up to temp and you run around 200 deg. Check on those thinhs and let us know.

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Or a stuck open thermostat, which would really be bad on the highway when you are getting the most cooling effect.

Thanks Guys!

It heats up quick enough and runs at 205-210 so I think the T-stat is fine. The heater hose from the water pump was not nearly as hot as the other one...

BingoJ i'll put my money on a clogged heater core. Leave the heater core hoses attached to the heater core unhook the hoses from the engine side. Jamb one hose inside a garden hose and slowly turn the water on and bring up the preasure. You will hopfuly be able to flush the junk out. Reattach the hoses and try it out. Let us know how you do.