Bad heating issue (sorry for another thread!)

[John3seventeen]

It's not opening , good you caught it!

 

[Birdman330]

As I used to tell customers, there's a reason why you have warranty on parts. There's a good 50% chance it won't work right out of the box.

 

[TwoBobsKJ]

Double check that you're installing the thermostat pointed the correct direction - many install it backwards. Check the other heating thread - LibertyTC posted a pic from the FSM showing the correct orientation. The long cone needs to be pointed into the block not into the lower hose.

To answer the other question posed: the upper hose returns the coolant from the radiator to the block and the lower hose sends hot coolant from the block to the radiator.

Bob

 

[uss2defiant]

https://www.youtube.com/watch?v=Nv0HpH2ymB4

 

[USCGjeep]

I know the thermostat is in the correct way, it's definitely facing into the block and i know that the bleed hole is also facing the correct way up because there was a specific way it would only fit into the hose with a small grooved part. But I'll be able to double check it once I see this weekend if it's defective or not. It's been single digits and negative the past three days so working on it is a no go haha

 

[profdlp]

...It's been single digits and negative the past three days so working on it is a no go haha

Ironic, isn't it? Too cold out to fix the heat. :shrug:

 

[USCGjeep]

UPDATE: So, took another shot at it. The thermostat is good, the original thermostat we decided to test too and that was good. They weren't the issue. The water pump is good to go, the impeller and everything is good and works.

Newest thought though, the fan. Obviously the purpose of the fan would be to cool down the coolant once it comes back out of the block into the radiator to cool it and put it back into the block and then it heats up again and repeat. So the fan should only be on once that thermostat opens and that hot coolant flows into the radiator, but my fan is on almost the full time. It'll kick on for about 60 seconds when i start the jeep, but it will come back on most of the time, even before the temp is up and anything and without that thermostat opening....any idea if this could possibly cause an issue?

 

[ltd02]

The fan relay would usually fail and the fan wouldn't work so maybe the coolant temp sensor (ECT)? If the ECT is messed up that way you'd probably not get a code. I think when, say something like a Tstat is stuck open it will sense the engine being cold after a period of time and send a code. Could use something like a scanner with live data and see how the temp output changes with run time. If its fubar then the temp probably is reading high relative to true most of the time.

Maybe someone else has a trick for testing this?

 

[USCGjeep]

Well i mean we replaced both the thermostat and coolant temp sensor so.... haha and i drive from cape may, nj to syracuse, ny (350~ish miles) with no issue. Temp has been sitting around the middle in both hotter weather in fall and colder weather before and after the new tstat and ect. Maybe just because it's been so cold and with the cold air circulating over the engine the coolant fluid just isn't hitting enough to open the tstat?

 

[ltd02]

Doubt it. Why did you replace the ECT initially? That would have been useful to know. I'd always go with Mopar sensors. New one could be defective too.

So is the fan running all the time or not? Do you have the defrost or defog on? That'll turn the fan on automatically too like having the AC on. Best to just have the heat on or turn everything off completely and see if the fan still runs. Mine hardy ever runs when I'm moving and seldom when stopped in the colder (10-30F) temps around me.

 

[tjkj2002]

To answer the other question posed: the upper hose returns the coolant from the radiator to the block and the lower hose sends hot coolant from the block to the radiator.

Bob

Got it backwards,I know for a fact since I have done more coolant flushes then I can count on 3.7's/4.7's.We use a short piece of clear hose in place of the machine while bleeding/getting the system at operating temps(t-stat open) so I know the direction of coolant flow.

 

[tjkj2002]

UPDATE: So, took another shot at it. The thermostat is good, the original thermostat we decided to test too and that was good. They weren't the issue. The water pump is good to go, the impeller and everything is good and works.

Newest thought though, the fan. Obviously the purpose of the fan would be to cool down the coolant once it comes back out of the block into the radiator to cool it and put it back into the block and then it heats up again and repeat. So the fan should only be on once that thermostat opens and that hot coolant flows into the radiator, but my fan is on almost the full time. It'll kick on for about 60 seconds when i start the jeep, but it will come back on most of the time, even before the temp is up and anything and without that thermostat opening....any idea if this could possibly cause an issue?

Need a scanner to see what the PCM is seeing as far a coolant temps,the electric fan should not engage till the coolant temp reaches 219(+/- 2 or so degrees),the fan will engage when any selection that involves AC operation and that does include defrost(both modes for the '02's).


If your system was as clogged as you say you most likely have a plugged heater core(might be leaking if you smell coolant).The way the heater core is setup flushing it will not clean it out,maybe 10% of the cores will have flow which will look like good flow but it's not just because of the design of the heater core.

 

[TwoBobsKJ]

Got it backwards,I know for a fact since I have done more coolant flushes then I can count on 3.7's/4.7's.We use a short piece of clear hose in place of the machine while bleeding/getting the system at operating temps(t-stat open) so I know the direction of coolant flow.

I had a "Doh" moment - thanks for the correction Troy. The upper hose gets hot first so of course it's sending hot coolant to the radiator.

My bad :shrug:

Bob

 

[USCGjeep]

Hmm...well i guess given everything that we've done i just will have to wait until summer and do the job and a half that is replacing the heater core. Probably take a couple days of leave to do that haha

one last question though, can somebody explain how the tstat works then, if the top hose is block to radiator and bottom is radiator to block...that confuses me haha Since the tstat is facing into the block i figured once the coolant heats up to temp, the tstat triggers and opens, and that hot coolant flows to the radiator and the top hose brings the cold coolant in and once that cold stuff reaches the tstat it closes?

Thanks again everybody for all of the help! From everything it sounds it's just that we flushed part of the core, but it's still plugged so i'll just have to do that come summer. I have better heat after the flush. Doesn't seem as though i have any sort of leak. I don't smell coolant nor do i have the dampness/fogging issue that i believe comes with a leaking heater core, correct?

 

[mx3_ryder]

I've been here!! Replaced my radiator which had a pin hole leak, thermostat and flushed system only to still have no heat. Culprit-heater core. Even though it was circulating, it was actually bypassing the core cause it was clogged. My mechanic did the job in 6 hours and charges $30.00/hr. Not even worth the headache imo to save a $180.00 plus an $80.00 core from NAPA. I'd find someone local that might do work on the side that knows what they are doing and save yourself the hassle.

 

[CalcityRenegade]

I had a "Doh" moment - thanks for the correction Troy. The upper hose gets hot first so of course it's sending hot coolant to the radiator.

My bad :shrug:

Bob

You're turn to get things backwards

 

[USCGjeep]

I've been here!! Replaced my radiator which had a pin hole leak, thermostat and flushed system only to still have no heat. Culprit-heater core. Even though it was circulating, it was actually bypassing the core cause it was clogged. My mechanic did the job in 6 hours and charges $30.00/hr. Not even worth the headache imo to save a $180.00 plus an $80.00 core from NAPA. I'd find someone local that might do work on the side that knows what they are doing and save yourself the hassle.

Well luckily my uncle has worked on cars for 30 years and he's the one who has been pretty much troubleshooting everything. I've just been watching, have to learn somewhere. But he'll be the one doing everything. All I'll have to do is buy the heater core! haha

I'm also a big fan of learning how to do things myself too. Manuals. youtube videos. Doing it myself or helping/watching are my ways to learn so I'd much rather watch it be done/help! :waytogo:

 

[mx3_ryder]

Well luckily my uncle has worked on cars for 30 years and he's the one who has been pretty much troubleshooting everything. I've just been watching, have to learn somewhere. But he'll be the one doing everything. All I'll have to do is buy the heater core! haha

I'm also a big fan of learning how to do things myself too. Manuals. youtube videos. Doing it myself or helping/watching are my ways to learn so I'd much rather watch it be done/help! :waytogo:

Even better, always nice having a mechanic in the family. There are just some jobs not worth the hassle and busted knuckles. Would way rather tackle an engine swap myself though which I am currently in progress on then change out a heater core... Funny I guess. I do most work my self, but send those can't even justify for the price jobs to my mechanic. Good luck!!

 

[tjkj2002]

Hmm...well i guess given everything that we've done i just will have to wait until summer and do the job and a half that is replacing the heater core. Probably take a couple days of leave to do that haha

one last question though, can somebody explain how the tstat works then, if the top hose is block to radiator and bottom is radiator to block...that confuses me haha Since the tstat is facing into the block i figured once the coolant heats up to temp, the tstat triggers and opens, and that hot coolant flows to the radiator and the top hose brings the cold coolant in and once that cold stuff reaches the tstat it closes?

Thanks again everybody for all of the help! From everything it sounds it's just that we flushed part of the core, but it's still plugged so i'll just have to do that come summer. I have better heat after the flush. Doesn't seem as though i have any sort of leak. I don't smell coolant nor do i have the dampness/fogging issue that i believe comes with a leaking heater core, correct?

The t-stat just blocks flow through the radiator,it can be placed on either end for the same effect.

 

[f4phantom.jw]

I don't want to hijack this thread but, I have a somewhat similar situation. My heater works fine until I get to a stoplight (or anywhere else it's just idling) and it immediately turns cold... Any thoughts on what the cause is?