Improving the cooling on our TJs

MountaineerTom said:
I don’t think so, however I didn’t have engine cooling problems. I installed it to see if it would help make the A/C a little cooler when idling or slow driving. I don’t really think it’s doing anything noticeable there either. Maybe a couple degrees on the little dial thermometer I have in the A/C vent.

I can feel a bigger drag on the engine than I feel cooler air. 🤣
Click to expand...

When I idle for long period of times in Houston heat, my temperature on engine can reach 231F.
I have 3 electric fans (one 6 inch and 2 4 inch) in the grill, blowing Air on the AC condenser. This keeps the AC working OK (not too cold, but still acceptable) even with engine running at 231F.
The electric fans in the grill can be switched on and off from the switch in the cabin, so if I shut them down, AC starts to be really weak pretty immediately.
 
  • Wow
Reactions: MountaineerTom
TexasTJ2004 said:
When I idle for long period of times in Houston heat, my temperature on engine can reach 231F.
I have 3 electric fans (one 6 inch and 2 4 inch) in the grill, blowing Air on the AC condenser. This keeps the AC working OK (not too cold, but still acceptable) even with engine running at 231F.
The electric fans in the grill can be switched on and off from the switch in the cabin, so if I shut them down, AC starts to be really weak pretty immediately.
Click to expand...

I'd check if you have an exhaust leak at the header.
 
LittleTankTJ said:
I'd check if you have an exhaust leak at the header.
Click to expand...

I don't hear anything coming from the exhaust manifold. No ticking and no smell of exhaust in the engine bay. I have visually inspected it, as good as I could.
What indication causes you to think that there could an exhaust leak?
 
TexasTJ2004 said:
I don't hear anything coming from the exhaust manifold. No ticking and no smell of exhaust in the engine bay. I have visually inspected it, as good as I could.
What indication causes you to think that there could an exhaust leak?
Click to expand...

I’m guessing due to you’re high IAT temps.
 
TexasTJ2004 said:
It always runs fine for me as long as I am driving, even in heavy traffic jam. The idle when engine temp goes into above 220F area and transition into 190F is where my problem is.
Click to expand...

I think your main problem is heat soak. You said your idling for extended periods of time and that is when the temps start to climb.
Also, at idle in park you are not flowing anything through the trans cooler. Try putting your jeep in neutral to see if the trans temp comes down some.
 
  • Like
Reactions: tr21triton
Just some usual options

Flush it with new coolant
Put a new thermostat in it
Water pump aged and decrepit??
Higher speed electric fans (& with that comes the necessary Alternator upgrade)

No vents up top trap the heat that rises
Some have done that vented hood and claimed it did help
 
Last edited:
When you mention extended periods of idiling.. are you talking about like 5-10mph crawling in traffic kind of idling in the middle of the day? Sorry if this has been answered already I skipped around the thread as well.

I'm in Houston and have never had any issues with my temp gauge climbing outside of anything normal. No special mods or anything to my airflow.
 
williambmac said:
I think your main problem is heat soak. You said your idling for extended periods of time and that is when the temps start to climb.
Also, at idle in park you are not flowing anything through the trans cooler. Try putting your jeep in neutral to see if the trans temp comes down some.
Click to expand...

It was maybe true for older transmissions. 42RLE (the auto for 2003 to 2006 TJs) oil pump works in park or in neutral.
 
CreepinDeth said:
Just some usual options

Flush it with new coolant
Put a new thermostat in it
Water pump aged and decrepit??
Higher speed electric fans (& with that comes the necessary Alternator upgrade)

No vents up top trap the heat that rises
Some have done that vented hood and claimed it did help
Click to expand...

Coolant is ~1 years old, same as thermostat, fan clutch and water pump.
I don't want to convert to electric fan, planning to stay with my mechanical, mainly because of reliability issues.
I do have hood vents, poison spider hood louver. It does help, judging on the amount of heat that comes through them.
 
  • Like
Reactions: CreepinDeth
jeepins said:
When you mention extended periods of idiling.. are you talking about like 5-10mph crawling in traffic kind of idling in the middle of the day? Sorry if this has been answered already I skipped around the thread as well.

I'm in Houston and have never had any issues with my temp gauge climbing outside of anything normal. No special mods or anything to my airflow.
Click to expand...

No, I am talking about idling for 50 minutes outside of a place where I take the kid for activities. This with AC and automatic transmission. Before I started idling, the engine temperature was 205F, manifold temperature was around 150F, and transmission was around 160F. Then idle, and temperature starts to climb slowly.
After ~40 minutes manifold reaches 237F (based on IAT sensor, which is in the manifold, old reading), engine 231F (based on old reading) and the transmission to 188F (I have sensor in the pan, routed to glowshift gauge).
In any form of traffic, as long as I move once in a while, it will be fine.
 
  • Like
  • Wow
Reactions: freedom_in_4low and MountaineerTom
TexasTJ2004 said:
It was maybe true for older transmissions. 42RLE (the auto for 2003 to 2006 TJs) oil pump works in park or in neutral.
Click to expand...

Have you thought of bypassing the radiator trans cooler and just run your auxiliary cooler? Also the cooler circuit in most auto transmissions does not pump all the fluid through the cooler like a cooling system does.
 
TexasTJ2004 said:
deal fellow TJers, I am looking into my TJ (4.0,42RLE) in which I am running new radiator, new coolant, new Hayden fan clutch, with properly working AC, and a winch mounted in the front. Thermostat and water pump seems to operate as expected, so don’t believe that I need to replace them.
What I see is that in stop and go traffic it gets always beyond 210, the same when parked in idle, even at the evening, with 87F outside.
I am in Houston area, so temperatures here easily reach 100F during the day. Also, as we all know the summers are getting hotter, so I am thinking about how to improve the cooling.
I have one step already on my schedule,. Which is adding Derale cooler for 42RLE, which will prevent the 42RLE from overheating.
Other step that is planned is to install louver (Poison Spyder), that will help to reduce the heat soak and heat buildup in the engine bay.
But, I am thinking about enhancing the engine cooling, using the following;
To tap into hot coolant line that go into the cabin, add a 3 way valve, that enables to route t he coolant into cabin or to additional cooler, and additional small radiator, with electric fan. I want to put somewhere near the Derale cooler for transmission, so that it takes away the heat from the engine Bay Area.
Before I jump into anything like, wanted to hear the opinion of experts here, I am sure that a lot of folks through about it before.

View attachment 344947

When you are idling with the a/c on all the heat removed from the cab is going into the engine compartment.
Click to expand...
 
MountaineerTom said:
I have the Derale 6 blade fan on a Hayden 2771 right now. It’s significantly louder that the OEM fan on the same 2771. I don’t think it has slipped any though.
Click to expand...

Louder doesn’t mean more airflow, remember the offset fins on a stock fan are intended to make it more quiet.

The slip sounds like a ringing bell, and only does it at max lock

I just got a mopar fan clutch and it feels about as aggressive as that Hayden heavy duty, and looks exactly the same BUT it must be tuned ever so slightly less aggressive when cold because it doesn’t cause my belt to squeak …
 
  • Like
Reactions: MountaineerTom
MountaineerTom said:
I’m guessing due to you’re high IAT temps.
Click to expand...

Fwiw, my true IAT temps are ridiculous from the turbo in my 05/06, and my coolant temps hold up just fine.

And the IAT sensor in the manifold is known to heat soak and read higher than what the IAT would read in the tube for the 05/06.

@TexasTJ2004 did you end up installing a mopar radiator?
 
  • Like
Reactions: MountaineerTom
Mikee024 said:
Fwiw, my true IAT temps are ridiculous from the turbo in my 05/06, and my coolant temps hold up just fine.

And the IAT sensor in the manifold is known to heat soak and read higher than what the IAT would read in the tube for the 05/06.

@TexasTJ2004 did you end up installing a mopar radiator?
Click to expand...

Not yet. Radiator still in the box.
 
TexasTJ2004 said:
Not yet. Radiator still in the box.
Click to expand...

That’s the move to make imo.

My previously amazing Mopar radiator got plugged up recently…and after a scale removal and thermocure I went from running too hot in idle and the highway to now being good again.

If your radiator isn’t flowing as well as a stocker, I’d throw the Mopar in immediately.

Edit: Btw my system held up this week when my IATs were 230* from the turbo and PHX was like 116* outside. Thankfully I flushed everything before making that trip.
 
Mikee024 said:
That’s the move to make imo.

My previously amazing Mopar radiator got plugged up recently…and after a scale removal and thermocure I went from running too hot in idle and the highway to now being good again.

If your radiator isn’t flowing as well as a stocker, I’d throw the Mopar in immediately.
Click to expand...

I am running AutoZone radiator now. I know, this is garbage:)
 
  • Like
Reactions: MikeE024
Top Bottom
Back