It's 2:00 am & I have been searching & reading, can't seem to find what I'm looking for. I changed water pump, thermostat/housing, all hoses, and flushed the system repeatedly, but still no heat in the XJ. The temp climbs (watching the indicator), the top hoses get hot. The lower core hose & lower radiator hoses are lukewarm at best and it's blowing cold air. Running water thru the radiator alone comes out clean. Currently I have the heater core hoses apart & I'm running water directly in/out the heater core only. Hoping the core isn't bad, but I'm still getting water that's not 100% clear. Which hose should I be putting the water in for it to be considered a "back flush"?

It's my first time doing this job on this (or any) XJ and I'm pretty sure I did everything right as far as disassemble/reassemble. I'm going to put it all back together in the morning and try again.

Any suggestions as to what I should check next?

 

I didn't think the heater hoses had a "polarity" when it came to flushing. Flush one way a bit then the other way. I Wonder if the core is clogged.

 

Yea could be clogged but I'm not familiar with the heating and A/C system on an '01. Anything in the controls to stop the flow?

I've flushed them both ways for years with no problems. Just don't use full pressure.

 

Not that I recall, I think she is flowin' whether you want it to or not. There are no heater control valves like in the older XJs.

But if one hose it hit and the other is like warm, that speaks to a restriction in the line.

 

Did you bleed the coolant system?

As EZEARL said, be careful to not use full pressure flushing the heater core.

 

I had to flush the heater core on the 99 twice. Flushed the feed and return lines. The first time did not make a difference with the cabin heat. The second flush removed what seemed like more sediment and now the heat works correctly.

 

Same here. Flush both ways until clear.

 

I'm not using full pressure, but I am using a special trigger on a garden hose, designed for this job.

I didn't put coolant back in the system yet this time. I was running the flush back thru it again. Didn't get a chance to touch it today, but on Sunday it will be all I do.

As for a clog, it would have to be in the core because I changed all the hoses. But the water seems to come out with about the same pressure I'm putting in, so I dunno what to think. Anyway tomorrow I'm back at it again.

I don't know how to bleed the system. How does that work?

 

Get the driver side nose up (front driver's wheel up on a ramp or a curb), pop the radiator cap, and run the engine to open up the thermostat. Now any air in the system should bubble out the open radiator cap. Top up as needed.

I think you are wise to hold off adding coolant until you get this solved. Once you know where the problem is, and have it fixed, you can drain and fill.

 

UPDATE:

I . Got . Heeeat!!

I am so pumped! Today I flushed the heater core like a dozen times ... shoulda seen all the stuff that came out of it! I had run water thru it before, but with I got on Amazon, it was a whole new experience. This thing is graduated so you get an actual seal where the water doesn't splash back in your face. Worked like a charm.
Then I undid the upper & lower hoses & washed out the dirty water from Friday, and ran water thru the rad again. Good thing we don't have city water or we'd be paying a ton of money for this month's bill, lol.

Considering that I had already put a new t'stat & water pump in before realizing that the core was still gunky, just wondering whether or not they're still ok. I ran a rust remover thru the system just in case there's anything in the block and/or radiator. No coolant yet - the rust remover is still in there. Will this mess up my new parts?

 

I would suggest getting a spill free funnel tool to help burp the system, you can get them off amazon or advance near me. Makes it very easy, and one trick is the give the upper radiator hoses a squeeze and you will actually see the air "burp" out of the system.

 

Ah ... good to know, thanks!

I did take BlueRidgeMark's advice & raised the nose tho. I watched the air bubbles come up until they stopped. Is it possible there's more considering the thing ran fine for 30 min?

 

It may sound dumb, but I stand on my off-road front bumper and jump up and down to get air out of the system. Works great. If you don't have a bumper to jump on. Just rock the front of the XJ by hand.

 

You should be good, I just did mine this morning and I ran it for 20 minutes. I think they tend to work themselves out, but if you have any idiling issues or overheating problems I would burp it again

 

Agreed. Glad you got it worked out!