No heat Still 2003 liberty 3.7L

[gbennett21]

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

 

[LibertyTC]

Have you tried to pressure test the system up to 16psi and see it it holds pressure for 5 minutes?
Auto zone may have the adapters to accomplish this or some shops may have it.
Have you been using mopar hoat coolant or Zerex G-05 ?

 

[gbennett21]

the jeep had green coolant in there when we got it so i flushed it with blue devil flush then went back with the correct fluid. also i havent done pressure test. i do know i have drain and ran water threw this thing at least 10 times thinking somthing was pluged and also every time i replaced somthing seems to flow fine. the last time is when i put a new water pump on. drain the system there was some rust flakes coming out with coolant this time. does anyone know which heater hose is the supply and return. one is 3/4 going back to engine above thermostat then the other is 5/8 going to thermostat housing. This line is also were coolant enters system from the fill tank.

 

[gbennett21]

the jeep had green coolant in there when we got it so i flushed it with blue devil flush then went back with the correct fluid. also i havent done pressure test. i do know i have drain and ran water threw this thing at least 10 times thinking somthing was pluged and also every time i replaced somthing seems to flow fine. the last time is when i put a new water pump on. drain the system there was some rust flakes coming out with coolant this time. does anyone know which heater hose is the supply and return. one is 3/4 going back to engine above thermostat then the other is 5/8 going to thermostat housing. This line is also were coolant enters system from the fill tank

 

[gbennett21]

parts that have been replaced are heater core old one was 80% blocked. i have installed 2 thermostat first one was from autozone. then i saw on here people saying order a mopar one. so i installed that. radiator was replaced before heater core because it had a leak and we didnt even need heat then so we didnt know heater core was bad yet. then the last thing we replaced was water pump. my next idea is to hook heater hoses together (bypass) heater core and see if i get flow threw hoses. if i do then know its not the engine blocked up. it would be either i bought a bad heatercore or just trapped air.If i dont get flow then not sure how to remove what ever is in engine. also if i didnt get all the old green coolant out how would i go about doing another flush just to be safe. im starting to get worried theat maybe when i put the correct fluid in there maybe it mixed with some green coolant i havent noticed anything. like i said i flushed it pretty good i thought and i have ran water threw system multiple different times looking at flow and replacing parts making sure its not clogged.

 

[sota]

do you continue to have good air flow out the vents, when the heat stops?

 

[gbennett21]

yes there's good air flow and all modes work on control unit. you can also tell when you change temperature setting from hot to cold.

 

[JeepJeepster]

If you get some heat when revving, that tells me you have a flow problem. Are you 100% sure the antifreeze isnt low?

 

[gbennett21]

yea cant be low if i have it filled up all the way to the no spill funnel.

 

[mikelikesbbq]

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

I'm not sure if this applies to a Liberty, but some cars have a control valve that opens/closes the flow of coolant to the heater core as needed. These can malfunction due to getting crusty, vacuum leaks or electrical issues such as a faulty HVAC controller. Perhaps one of the more experienced guys can chime in and confirm if the Liberty has a valve for the heater core plumbing. Just a guess but hope it helps point you in the right direction. Good luck!

 

[LibertyTC]

A pressure test is required. If it won't hold pressure, that means air is entering the system & will cause fluctuating heat.
Check the reservoir cap, it should be 16 psi and look for any cracks in the gasket below the cap etc.

 

[gbennett21]

ok will check with pressure tester.not sure if it could be the radiator cap. I also replaced the tank on this when i did radiator because it was full of junk and i couldnt get it all out. it came with a new cap

 

[mikelikesbbq]

ok will check with pressure tester.not sure if it could be the radiator cap. I also replaced the tank on this when i did radiator because it was full of junk and i couldnt get it all out. it came with a new cap

I saw a recent video on YT where they had some issues and it ended up being a faulty sealing surface on an aftermarket ebay special coolant tank. They ended up putting a junkyard one on to solve it It may be unrelated, but worth checking the tank out closely for any burrs or poorly finished surfaces where the cap attaches, especially if it's an aftermarket unit.

 

[gbennett21]

do anyone know which is the supply line to heater core. when i looked it up it doesn't say but if i look up part on autozone website it says the 5/8 inlet and outlet is 3/4 the outlet if that is the case the outline line is the line that i pump and it gets hot then. is it possible i bought a heater core that is not flowing like it should. When i tested it water ran threw no problems.

 

[tommudd]

do anyone know which is the supply line to heater core. when i looked it up it doesn't say but if i look up part on autozone website it says the 5/8 inlet and outlet is 3/4 the outlet if that is the case the outline line is the line that i pump and it gets hot then. is it possible i bought a heater core that is not flowing like it should. When i tested it water ran threw no problems.

Problem with the heater cores is water can seem to flow through fine but be plugged
They have a sort of bypass in them where your coolant can go in but not necessarily go clear through the heater core itself
can seem to be flowing well . but not doing what it supposed to

 

[gbennett21]

thats what i was thinking but im not sure if coolant is even going to the heater core. if i pump the hose(squeeze) i can get coolant threw the heater core which then i have heat. but it goes away. with temp gauge in vent i can get the heat up around 140° out the vents but it slowly goes back down to around 70°. its like its no circulation to the heater core.

 

[DadOSix]

Problem with the heater cores is water can seem to flow through fine but be plugged
They have a sort of bypass in them where your coolant can go in but not necessarily go clear through the heater core itself
can seem to be flowing well . but not doing what it supposed to

I’m thinking he replaced the core at the top of the post.

 

[gbennett21]

yea just wondering if i got a bad one.i pre filled it with coolant when i installed it. but the funny thing is when i flushed the system the last time i can tell that the coolant i prefilled in heater core was still the same coolant. and thats after a full week of driving. so thats why i believe im not getting circulation. im going to try and burping the system in the morning again on ramps at the end of driveway. i was also thinking of pulling one of the heater core hoses off while at idle and see if i have any flow i know the smaller 5/8 hose has pressure but the larger 3/4 hose you can pinch shut and it seems like its kind of soft like its getting old. so one heater hose is firm the other is soft.

 

[tommudd]

I’m thinking he replaced the core at the top of the post.

Yes I know he did, but doesn't change the way things workout at times

 

[bump]

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