No heat Still 2003 liberty 3.7L

wesswires

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I had this type of issue on an 05 when I got it. Going down the road there was heat and no heat when at a traffic light. It took a while but later it started overheating, or superheating the coolant. This is going to sound like like a long crazy story but my heater works great now.

Turned out the head gasket was cracking and exhaust was getting in to the coolant. The exhaust gas and boiling probably prevented heat into the core. Later I figured out that the radiator fan has 2 temp signals (High, Low) and only the high signal was working on the fan. That may have caused the head gasket problem in the first place. So if you replace a head gasket, I suggest checking both signals on the exhaust fan.

It would be worth getting a test kit that will detect exhaust in the coolant to see if that's what is happening to yours. If not it sounds like air in the line.

I hope it's not your head gasket. But if I had another head gasket problem I would not spend $1000 to replace it. I'd get a rebuilt engine for $2000. There are a couple of sellers on ebay that sell them.

To test the water pump with the hose that goes from the radiator back to the reservoir, disconnect the reservoir and start it up cold. The coolant should immediately flow out the hose. When hot (thermostat open), it won't flow out this hose it will go through the radiator and back to the heater core and engine.

Blessings,
W
-Prosperity and health provided by the Lord Jesus.
 
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gbennett21

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Im starting to wonder if something is wrong with the water pump.
i just installed a new water pump last saturday. I end up getting the same results i wounder if the engine when full of fluid there is something blocking the outlet or inlet connection to the heater hoses
 

gbennett21

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I had this type of issue on an 05 when I got it. Going down the road there was heat and no heat when at a traffic light. It took a while but later it started overheating, or superheating the coolant. This is going to sound like like a long crazy story but my heater works great now.

Turned out the head gasket was cracking and exhaust was getting in to the coolant. The exhaust gas and boiling probably prevented heat into the core. Later I figured out that the radiator fan has 2 temp signals (High, Low) and only the high signal was working on the fan. That may have caused the head gasket problem in the first place. So if you replace a head gasket, I suggest checking both signals on the exhaust fan.

It would be worth getting a test kit that will detect exhaust in the coolant to see if that's what is happening to yours. If not it sounds like air in the line.

I hope it's not your head gasket. But if I had another head gasket problem I would not spend $1000 to replace it. I'd get a rebuilt engine for $2000. There are a couple of sellers on ebay that sell them.

To test the water pump with the hose that goes from the radiator back to the reservoir, disconnect the reservoir and start it up cold. The coolant should immediately flow out the hose. When hot (thermostat open), it won't flow out this hose it will go through the radiator and back to the heater core and engine.

Blessings,
W
-Prosperity and health provided by the Lord Jesus.
i did that about 2 weeks ago thinking headgasket was causing exhaust to leak in coolant system. i neve could get the fluid to change colors. i tested the fluid to make sure it was good by putting it to the exhaust pipe and it did pass that test but testing the reservoir i never got it to change color.
 

JeepJeepster

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Very odd... Just not sure what could block the passages going to the heater core, but I guess the next step would be to check to make sure those are open and flowing freely.
 

SWilliams

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Hit your local home store and buy a short piece of clear vinyl line and a coupler, install that in one of the heater core lines, start the engine and watch for flow. Next you say you replaced the thermostat and the core, pump and flushed with no change. When it's running do the heater hoses get hot? FYI larger hose is inlet, smaller is outlet, The restriction is intended to keep the coolant in the core longer to give more heat. If the hoses don't heat up then you would get no heat, what does the fan do during all this, does it have the heavy duty cooling option with the electric and a mechanical clutch fan? Quick test for that is to block airflow through the radiator with a chunk of cardboard and see if you have heat. Do you have access to a scan tool or code reader that can pull live data? If so what does it show for coolant temperatures and how long did it take to get to that temperature?
 

gbennett21

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Hit your local home store and buy a short piece of clear vinyl line and a coupler, install that in one of the heater core lines, start the engine and watch for flow. Next you say you replaced the thermostat and the core, pump and flushed with no change. When it's running do the heater hoses get hot? FYI larger hose is inlet, smaller is outlet, The restriction is intended to keep the coolant in the core longer to give more heat. If the hoses don't heat up then you would get no heat, what does the fan do during all this, does it have the heavy duty cooling option with the electric and a mechanical clutch fan? Quick test for that is to block airflow through the radiator with a chunk of cardboard and see if you have heat. Do you have access to a scan tool or code reader that can pull live data? If so what does it show for coolant temperatures and how long did it take to get to that temperature?
ok so just got done for today this is what i found out. larger heater hose you have to pump to get hot. top radiator hose gets hot bottom cool then thermostat opens electric fan comes on bottom hose gets hot so seems to flow there when thermostat opens. small heater hose gets hot all the time and has pressure when you squeeze it. but larger hose which is 3/4 only gets hot if you squeeze it and hold it or pump it but never gets pressure on its on. with a meat probe to watch vent temps. i see when thermostat opens temp goes up but after fan kicks off the vent temp goes down.vent temp with car fully warmed up fluctuating between 80° if i dont do anything and just idle. to around 100° if i start reving engine and pumping the bigger hose on heater core. Everything in system has been replaced. Im thinking head gasket because i can see smoke from exhaust if i hold engine at 3500 rpm for 30 seconds . Theres no bubbles in coolant when i do this also this thing has never overheated. i mean today i drove around 2.5hrs highway and some city no smoke. seems to smoke only with a really heavy load on engine(high rpms) if you drive normal it never smokes. if its not that then it has to be a bad heater core from oreillys. it acts the same as the old heater core which we cut open because it started to leak after blue devil flush. it was about 80% blocked.
 

Ksat

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Based on your description, I'd say you've got a bad heater control valve

I may be wrong, but I believe those heat control valves were used on older vehicle setups before Libs came on the scene. They basically worked like a butterfly valve; shutting off coolant flow to the core when the temp dial was turned full cold, and then allowing full flow of coolant in when the dial was turned to full hot. I think the setup was phased out because during the warmer months, when one would typically have the temp control dial always set to cold, the coolant that was in the core just sat in there and corroded things up, causing it to fail prematurely, especially on cars whose coolant was in poor shape to begin with.

With todays blend door setups, coolant continuously flows in and out of the core (being shared with the rest of the system), regardless of heater dial position. Instead of controlling the amount of coolant coming into the core, the dial now controls the blend door, which in turn changes where the airflow originates from.

Anyway, on to your problem.. from your description, it sounds to me like you have air in the system. It is slightly unusual that you're not getting temp gauge fluctuations along with the lack of heat, but the fact u can get heat for at least a little while when you play around with the heater hoses points me in that direction. Why you have air in there would be the question to me. Either you have an air pocket floating around in there from when you changed out the rad, or you have air entering the system from something like a bad head gasket.

If it were me, I would do a block test to see if exhaust gasses are entering the coolant system. Autozone rents the kit out (with fluid) for nada once you're done and bring it back. Another test I like to perform, though more time consuming but usually more than conclusive than a block test (esp. for small leaks), is to pump compressed air into each cylinder via the spark plug hole with piston at TDC and hold it there for a good 5 mins while viewing coolant level at the reservoir. If level goes up, you know you've got a problem.
 
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gbennett21

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I may be wrong, but I believe those heat control valves were used on older vehicle setups before Libs came on the scene. They basically worked like a butterfly valve; shutting off coolant flow to the core when the temp dial was turned full cold, and then allowing full flow of coolant in when the dial was turned to full hot. I think the setup was phased out because during the warmer months, when one would typically have the temp control dial always set to cold, the coolant that was in the core just sat in there and corroded things up, causing it to fail prematurely, especially on cars whose coolant was in poor shape to begin with.

With todays blend door setups, coolant continuously flows in and out of the core (being shared with the rest of the system), regardless of heater dial position. Instead of controlling the amount of coolant coming into the core, the dial now controls the blend door, which in turn changes where the airflow originates from.

Anyway, on to your problem.. from your description, it sounds to me like you have air in the system. It is slightly unusual that you're not getting temp gauge fluctuations along with the lack of heat, but the fact u can get heat for at least a little while when you play around with the heater hoses points me in that direction. Why you have air in there would be the question to me. Either you have an air pocket floating around in there from when you changed out the rad, or you have air entering the system from something like a bad head gasket.

If it were me, I would do a block test to see if exhaust gasses are entering the coolant system. Autozone rents the kit out (with fluid) for nada once you're done and bring it back. Another test I like to perform, though more time consuming but usually more than conclusive than a block test (esp. for small leaks), is to pump compressed air into each cylinder via the spark plug hole with piston at TDC and hold it there for a good 5 mins while viewing coolant level at the reservoir. If level goes up, you know you've got a problem.
Thank you man that was a very good read about how the cooling system work. Im sure its air in the system but getting it out has been the problem. Im also thinking i might have a small head gasket leak not enough yet to cause overheating but just enough to put air in coolant. I will do the compression test. I already did the block test with fluid and i got nothing. just not sure if it only leaks when theres a load on engine. i rev engine and did this test about 5 min got nothing i know fluid works because if you take tester to exhaust pipe it changes instantly.
 

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uss2defiant

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i would try to use an IR thermometer gun to look at the temperature of the hoses going in and out of the heater core.
I would think there would be a few degrees difference if you have the heat on in the cab going.
If there isn't a difference, perhaps the heater core is bad.
 

WheelNut

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Would a dealer be able to get the air out with a pressurized flush of the system, or would that not force trapped air out? Interesting journey you are on here. You are really exhausting all the possibilities!
 

Ksat

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A compression test won't necessarily rule out a bad head gasket/cracked head, especially if the leak is slight. If end up doing one, though, make sure to take the cap off the coolant reservoir 1st.
 

eradicator006

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Some good ideas here. One thing I didn't see mentioned is how did you fill the cooling system? When I did my radiator in 2016 I had to fill the coolant through the bleeder port on the upper hose otherwise I had air in the system. It does seem like you have air in the system. If all of the other tests check out I would just drain the system and fill it back up through that bleeder port.
 

wesswires

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-That's what mine did- Chapter 2 of 'My Head Gasket': I had the jeep for about several months or a year with the heat acting odd (see previous post). Then one day it overheated. Then it was fine for weeks. Then it did it again, and again with less time passing between episodes. I could drive it 100 miles on the highway without any problems. Then when I got into town and slowed down to 45, the heat wasn't being removed by the wind from highway speeds and it would overheat.

If you've replaced the core and you have heat at the bottom of the radiator it really is sounding like it's the gasket.

You could keep driving it for awhile and keep testing the coolant. You could also bypass the heater core with clear tube and some fittings, maybe you could see bubbles when you rev it up. Watch the temp! Once it get's above normal it doesn't take long to reach the peg. If the temp gets all the way to the the 'H' the computer will shut down the engine. Then it takes a long time to cool down if you can't release the pressure. The reservoir cap with a release valve comes in handy in that situation. I didn't get that cap for this purpose. I purchased it because I thought that it might not be sealing. Have you tried that? It would be a blessing if it it's the cap and not a gasket. The good news it that all went away with the new head gasket.

Hope this info helps.
-W
 
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ditch204

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So this may sound stupid but I’ve done it. Did the new hc come with a cap on the inlet and outlet. I’ve installed one where the end of the cap broke off and wedges itself in the port. There is flow but not that much. Something to check.
 

Corey

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Guys i have watched every youtube read every thing related to this 2003 liberty. It started in june radiator cracked. replaced it then last month son teyed to use heater. No heat so i work on it evey weekend i tryed flushing system with blue devil and heater core started to leak. replaced heater core still cant get heat unless i pump the 3/4 hose on heater core. but eventually the heat in cabin goes from 140° to 80°. I mean heat wont stay flowing to heater core. When i did heater core i checked blend doors work fine also cut hole in hvac box and i can see it working and also tell theres no heat coming from heater core. so we said maybe thermostat. Ok got one from parts store. no luck so order a mopar one from rockauto. no luck tryed flushing more. Also disconnected heater hoses ran water threw there fine ran water threw engine block with heater hose off thought maybe the outlet on the engine block was blocked maybe used screwdriver felt somthing in there but not sure if it was. flushed again with water came out fine. still no heat. so i said well maybe waterpump is wore out. replaced it even though nothing was wrong with the other one. still no heat. when i fill up every time i have it parked at end of driveway slop on ramps with a no spill funnel bleeder ***** open 45min. bubbles stop. after some time but still no flow to heater core. i rev it up 3000rpm 30 seconds let off i can see more bubbles when i give it gas. which im thinking is that a head gasket leak. car doesn't over heat or smoke i can idle all day no problem and i drove it 4hrs straight with out a problem with over heating. so just dont make sense to be a headgasket. I had two other guys look at it they do work on jeeps and other cars alot and they cant seem to figure it out. dont make sense only thing left to replace would be the two heater hoses.i dont loose coolant and car dont over heat. so maybe air stuck in heater core?if so i cant get it out i have idled on ramps with the no spill funnel for 2hrs before. going out rev engine every so often. If i keep reving engine i can get heat to come up slowly but it starts to go away soon as i let of gas. I use a thermometer in the cabin vent to watch the air temp so i can see temp go up then down.Its like im not getting circulation to heater core also which hoses is intake hose to heater core one is 5/8 the other is 3/4
There is a bleeder ***** at top of engine where radiator hose goes to the block have you tryed bleeding air from there
 

gbennett21

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yea i actually filled it from there last time i drained the system because i saw that people had luck with it. im just lost with this i will update you guys if i find out anything. Thanks for the help.
 

Robochop

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I don't mean to question your methods, but have you checked to make sure you have the thermostat in correctly? It's easy to put this one in backwards if your not paying attention. Have you also tried bleeding the air from the hex key ***** on top of the upper hose neck? I have attached a pic just in case. (sorry about the pic, I'm doing some valve spring work to mine!)
 

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gbennett21

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yea i tried running engine untell its up to temp then open bleeder and leave open until air stops bubbling. then i also tried draining system and refilled at the bleeder untell i coudnt get any more. far as thermostat goes i believe it can only go in with the spring facing inside the engine. thats the way i pulled the original one out. i also tryed different positions with jiggle valve on thermostat and i also removed the pin in the jiggle valve. looking at the service manual and using AllData diy im pretty sure the direction of thermostat is correct. The only thing i noticed that kind of bugs me is. There are two hoses that go to the heater core off the engine. one is right behind the thermostat and the other runs just above it and it looks like it goes to engine to the water pump threw channels i noticed when i took water pump off that it looks like the 3/4 hose does somthing with water pump if i stick somthing in that connection its almost like its plugged. but i clear it and i run water threw it fine. i even had water pump out and decided to use water hose were water pump goes. and i can get water to come out were the thermostat is (with the thermostat off) and if i cover the thermostat hole water comes out the other heater hose connection. kind of har to explain. but just imagine every hose disconnect from engine and the water pump off and you fill with water well it comes out thermostat housing. if you stick your hand over that then it comes out the other connection to heater core. so im left with two ides either i have blockage that occurs when engine is full like somthing floating around in engine or small head gasket leak. like i said if i get engine up to 3500 rpm for long time just putting a load on engine i do notice some smoking. but no smoke when driving or idling. also temp gauge has never past the middle and the exhaust gas tester never failed the test even after reving engine.
 

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