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heat not hot(searched)

A

awglx

NAXJA Forum User
Location
ct
OK so my girlfriend 00' xj blows mildly warm air in the cabin. This past summer she over heated because the water pump rotted away and cloged the flow(only 5 years old). So she has a brand new water pump and the coolant was nasty so I flushed it last weekend and that didnt help.(with the heat)

I was hopeing that it wasnt a heater core problem but thats what it looks like?

should I try and flush it again and focus on the core?

Does the heater core need replacing? Big job? I know it is on my vw.

Thank you for your time guys.

Adam
 
I also will like to know. My brother's TJ is the same and he had a new radiator put in recently too.
 
Is your engine reaching proper operating temperature? If yes, I would lean towards the heater core. If no, you may want to check your thermostat to see if it is stuck open.
 
forgot to mention new thermostat and the car is at 200 to 210 f

back flush the core?
How?
Disconnect two lines from pump and flush?
 
How does your heater control valve look? I overheated also and replaced everything and notheing helped until i replaced the heater contol valve..Just my 2¢
 
josh89xj said:
How does your heater control valve look? I overheated also and replaced everything and notheing helped until i replaced the heater contol valve..Just my 2¢
Click to expand...
Dont know. Where is that?
 
For what it's worth what kind of backflush did you do was it the 20min one or the one where you actually leave it in for somthin like 12 hours and driving.
Extremely clogged systems may require 2 back flushes.1 to loosen all the crap.2 To clear out all the loose crap.If the water pump disentegrated like you said that may be the problem.Did you check the lower radiator hose to see if it has any obstructions.
Not making this sound like you don't know what your doin,but when I backflush I always do it 2 times,the top off with straight water...let it get to op temp check all the hoses/clamps...drain it...stick a garden hose in hoses going to the heater core and backflush it individually..1st the top hose then
the bottom..then hook it all back up top off with water..check for leaks ..drain.If there is any doubt about the t stat change it out.Loosen the belt(s) and see if you can move the waterpump pulley other than around in a circle..as side to side or top to bottom..if it moves any way other than in a circle...It's toast change it out
 
thanks, your right this was my first time.
I drained lower hose(found no blockage)
filled with water, ran it a few min.
drain
fill again w/ water and the quick radiator flush sh!t
ran it at operating temp for short while(heat on full)
drain
ran water through
fill
drain
fill w/ water and coolant

I didnt focus on the heater core
 
I think I am probably going to have to flush it again this weekend
edit: I also have to check the heat control valve. could be damaged from overheating, crud, or me changing plugs. Right?

btw: thanks for all the help so far
Adam
 
Last edited:
awglx said:
I think I am probably going to have to flush it again this weekend
edit: I also have to check the heat control valve. could be damaged from overheating, crud, or me changing plugs. Right?

btw: thanks for all the help so far
Adam
Click to expand...
Yep that control valve is back by the rear plug, you could have knocked the vacuum line off.
 
What years were there a heater control valve, because my heater core doesn't have one and its a 98? Also before I flushed my heater core my temperature was very unstable(160-200 degrees) and after I flushed it ran consitently between 210-215 degrees. I assumed it was because the thermostat was forced open by the pressure from the water pump, but thats just my shade tree mechanic overview of the situation, I could be wrong.
 
Jeremycj7 said:
What years were there a heater control valve, because my heater core doesn't have one and its a 98? Also before I flushed my heater core my temperature was very unstable(160-200 degrees) and after I flushed it ran consitently between 210-215 degrees. I assumed it was because the thermostat was forced open by the pressure from the water pump, but thats just my shade tree mechanic overview of the situation, I could be wrong.
Click to expand...
I have never seen one without.
 
No valve on the 97+. Coolant constantly flows through the core.
I had to flush the core on my wifes 97 XJ last winter due to the same problem you are having.
I just popped the 2 hoses off and grabbed a hose from the house and hooked it up to the heater hose. Pump water through it in each direction for a alternating every few minutes. You would not believe the crud that came out of it even after several minutes of crystal clear water coming out, every now and then a big rust patch of water would come out.
 
JEEPZZ said "No valve on the 97+. Coolant constantly flows through the core."


I have a 2001... does this mean there's some sort of air-duct valve to divert air around the heater box when you don't want heat? Maybe that's not shutting properly...

Thanks,

Andy
 
Yes that's correct.
Make sure your temp gauge gets up to about 200-210 for normal operating temps (97-01) if it doesn't, try the T-stat first.
 
Ok, so on a whim I pulled the knob off the heat control, and I was able to turn the post another 2 "clicks" toward cold. What do you know but the air comming out of the vent cooled to the ambient temperture (it was around 60 today in San Jose).

I turns out the knob is keyed such that it requires the post to move 2 clicks toward hot in order for it to be seated properly. I don't know if this was a design defect, or maybe the underlying heater control wasn't mounted behind the panel correctly.

Regardless, a little work with a file allowed for the knob to be mounted on the post while maintaining cool air. Problem solved... go figure.

I probably should add I've only had this XJ for a few weeks... I wonder how the prior owner lived with the extra heat in the summer!

-Andy
 
Andy said:
I turns out the knob is keyed such that it requires the post to move 2 clicks toward hot in order for it to be seated properly. I don't know if this was a design defect, or maybe the underlying heater control wasn't mounted behind the panel correctly.

Regardless, a little work with a file allowed for the knob to be mounted on the post while maintaining cool air. Problem solved... go figure.

I probably should add I've only had this XJ for a few weeks... I wonder how the prior owner lived with the extra heat in the summer!
Click to expand...


A/C.

Seriously... my '00 has always blown "warm" air from the vents, even when the temp control is all the way down. I wonder if this is a common defect?
I just assumed it was all that underhood heat that we always worry about!

No issue now... as it's not even gonna get up to 30 until Friday, but something to look in to!

Den
 
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