I'm freezing!!

I have flushed and reverse flushed.I have used cleaner in my cooling system.I have made sure the heater valve is allowing coolant to flow to the heater core......

and still luke warm heat!!!

The last time I flushed/reversed through the heater core I did so until there was only clear water flowing out so I assumed it was flushed completely but the air that comes out of the vents is barley warm and has been that way since I bought it three years ago!!

What am I missing here?

you got a thermostat in that dog?

downshifter2006 said:

you got a thermostat in that dog?

Click to expand...

Yeah ... I agree ... check your thermostat. I had the same problem on my old Chevy truck. Turns out the Thermostat was stuck open. Changed it out and heat was hot again.

get the dealer tstat - I only do this because it's 8 bucks with gasket, small price to pay in my mind (i've had bad aftermakert tstats.) make sure you have a bleed hole, make sure the bleed hole is at 12 o'clock. goodnight, and godspeed.

I have a new stant 195 deg and it is working(I think)already have holes drilled at 12 and six last month when I dropped my new motor in....

I don't think it's undercooling because the temp gauge reads 210 and the weather here is in the 20's (f)

So what next?
Does malt vinegar really work to clean out heater cores?

Sounds like the valve that allows the hot water hose to feed the heater core may be bad, or a vaccum line that controls it.

Start checking at the hoses that feed though the firewall.

Have someone move the temp from cold to hot, and look for the valve to move, then move it from hot to cold, wait a minute, back and forth, keep looking for it to activate. Also check the vac line thats connected to it. Maybe a vac leak under the dash. Oh joy, keeps getting funner!

Post back...

nope,not the valve(I have it zip tied open)

Damn guy, I dohno... Let us know when u figure it out though!

How did you flush?
You removed both hoses from the firewall and flushed straight in and out of the heater core, right? Both directions just to be sure?

I was also going to suggest checking each hose section for wear and/or blockages. I have seen where an old hose will look okay, but when under pressure a piece of rubber pushes loose and causes a blockage.

The heat exchange valve was also a good idea to hold open.
I had to replace this recently because the top hose fitting broke.
When I went to the boneyard to pull one, I discovered that the plastic hose fittings on the valve kept breaking. They would just crumble. I think the heat and age just wears it down. Perhaps this is what is happening to your valve – the plastic is crumbling on the inside???
I looked at 12 XJs before I found a good one.

Water flow – you say that your temp is at 210? That sounds like the pump is working.
Not exactly sure how to check water flow except for a visual check while letting it run for a second or two - having a hose disconnected from the output of the heat exchange valve.

Have you tried this simple test? Get everything up to temp, then hold the hose at spots from the engine out to engine in. You should feel hot everywhere. Important spots obviously would be engine out, valve in then out, heater in then out etc. If you find a cooler spot your blockage is between there and the last hot spot. If the heater core is plugged any radiator shop can redo it for you.

Check right above the gas pedal for a vacuum hose off. (or if you have a dent in the right front side of your bumper, the vacuum ball is probably busted!)

I have a 98 I bought in October 05. As winter approached I realized I NO heat. I flushed the Heater core in and out - like you - but I was still cold. I put in a new stat - NO CHANGE.

I finally took it to the stealership and they flushed the heater core AND the block........Now I have HEAT !!!!

I have no idea how they flushed the block .... and all they used was a standard garden hose. If any one knows where I hook up the garden hose to flush the block and heater core - - PLEASE LET ME KNOW.....cause that's what finally fixed it.

I would suggest trying what Gniederg did. If that still does not correct the problem, I'd say its time for a new radiator! Have you had it pressure tested yet, cause that will tell you a lot if something is wrong. Just my two pennies........

Gniederg said:

I have a 98 I bought in October 05. As winter approached I realized I NO heat. I flushed the Heater core in and out - like you - but I was still cold. I put in a new stat - NO CHANGE.

I finally took it to the stealership and they flushed the heater core AND the block........Now I have HEAT !!!!

I have no idea how they flushed the block .... and all they used was a standard garden hose. If any one knows where I hook up the garden hose to flush the block and heater core - - PLEASE LET ME KNOW.....cause that's what finally fixed it.

Click to expand...

I would venture a guess that they hooked it up to the heater outlet on the t-stat housing and disconnected the lower rad hose.

Have you check the blend doors?? I know the Grands had problems with them not working. If the door inside is not working little to no heat will come out. Anther thing it might be but i don't think is you have a air pocket in the system, 4.0L can be a pain to get all the air out. Just give you a few more thing to think about

warpigxj said:

Have you check the blend doors?? I know the Grands had problems with them not working.

Click to expand...

That would be my vote.

I called the Stealership to see if they would tell me what they did. AND THEY TOLD ME !

HEATER CORE FLUSH:
They disconnected the top and the bottom heater hoses at the block- where the Tstat is. (Not the fire wall)
- Connected the gargen hose to the top hose and flush it through the heater core and out the bottom hose.
- Then connected the garden hose to the bottom hose - flushing the heater core backwards out the top hose.

Connect everything back up.

BLOCK FLUSH:
They said to flush the block - they removed the Tstat
- disconnected the Bottom heater hose
- Connect the garden hose to it.
- turn on the water
- flush the heater core into the block and out through where the hose was connected.


Connect everything back up.

- remove the top hose
- connect your garden hose to that hose
- flush through the Heater core and through the block and out where the hose was connected to.

REPLACE YOUR THERMOSTAT

YOU'RE DONE

Thanks for all the replies...

I had the radiator flushed before I dropped in the new motor.The block is clean because it is a new motor...the old block had an amazing amount of crud built up in the passages,enough to almost totally block the passages!!So I know the cooling system was serverly neglected by the previous owners....that is why I started flushing everything.The vacuum tank behind the bumper is a new dealer item that I replaced when I first got the jeep(had a hole in it)the vac lines are good because over the past few months I tested everyone with my mity vac gauge.As of now I have the valve zip tied in the open position...

I doubt there is air in the system because I drilled a bleed hole in the new t-stat I put in(at 6:00 position and one at 12:00) I will however pull the sender at the back of the head and bleed to make sure.

The only thing that it might be is the "blend door".....never really thought about that so thanks to whoever suggested it.Although it blows out plenty of air in all the positions(def,heat,vent,ect.)

How do you guys suggest checking the blend door?It's pretty far up in the dash,isn't it?

One more thing,is it possible to "boil" out the heater core while it's still in the jeep?

Thanks

try blowing the heater core out with compressed air but dont i repeat DON'T us more than 75# of air pressure. if there is some blockage this should dry it out and hopefully make it come out next time u flush.