AAIIIC

iTrader: (19)

The rate of heat transfer is proportional to mass flow rate of the fluid. "Slow the coolant down so it spends more time in the radiator" is one of those suggestions that pops up in every engine cooling thread on the intarwebs, but it is flawed logic.

Now, if the pump is being spun too fast and cavitating excessively, thus reducing the flow rate, then slowing the pump down could help.

knaffie

Makes sense. It's the OEM water pump and crank pulley, so that should not be the case.

I edited my link to include the fan I have. I'm waiting on a call back from Spal with any recommendations.

BLKMGK

What's timing look like under load?

knaffie

I don't have the ability to look at timing. Turnkey Engine Supply tuned it on their dyno. I can only assume it was done correctly.

BLKMGK

No obdii port onboard? Tried removing the winch just to see if there's a difference?

knaffie

I have OBD2 port, but nothing to use to look at timing.

I could remove the winch, but it's somewhat irrelevant. It has to be on there and there's no way to mount it any lower than it already is.

knaffie

From Spal: "You are using the recommended fan for this type of application. To gain higher airflow you need a dual fan setup which I don’t think you will have room for on the Jeep. If you think there is room for a dual 11” or 12” fan setup let me know and I can make some recommendation."

gpphantom

Was a solution or solutions ever found? I have a 2006 LJ with a 5.3 LH6 that has heating issues. They seem to be at speed rather than RPM(?) Over 68 mph it heats up. If I drop back to 60, maybe 65 it cools off some. Tried all the obvious fixes and wonder if it’s a cavitation issue, but could be airflow. BTW, mine was Turnkey’s first LJ. Thanks

LS1 TJ

Seems so odd the heating problems. I have a LS6 in my 98 Wrangler. Single 16" Spal fan. No shroud around the fan. Never had a heating problem. 187 degree stat. Fan on at 210 and off at 195 controlled by the ecm.

Are you sure all the air is out of the cooling system? Maybe a bad stat?

I've had my Jeep in 100 plus heat and still no problem. I do not have AC.

knaffie

I didn't read back to see what I posted or didn't. I have a L92 (6.2) in my Jeep with a Novak radiator and single 16" Spal fan. I spent thousands of dollars throwing parts at it and trying different things to keep it cool. It keeps cool (under 210) unless I push it hard. Uphill for 15+ minutes @ 55+ MPH on the highway (think Sacramento to South Lake Tahoe) or really running hard for 5+ minutes in the sand or offroad, it's at 240. Every person I've talked to that actually runs their Jeeps hard and have a similar setup (swap radiator and single fan) have the same problem, but many of them don't speak out about the problems, presumably because of pride. A lot of the JK Hemi swap guys report similar experience. JK has more grille width, so it's easier for them.

If you want to race it or run it hard, like at the dunes, you need a $$$$ custom setup. Ultra 4 guys put a radiator overhead behind the passenger's heads with two 12" or 14" fans. It'll never get hot. Two guys I talked to paid $$$$$ to have a custom radiator made with two 12" fans or three 10" fans in the OEM location. Lots of $$$$$$ labor to make that fit properly, but it works.

I just drive mine reasonably knowing that if I really get into it, it's gonna get hot and I need to let it rest to cool down. I'm fine with that.

Q8y_drifter

Bumping this thread back up since we're having the same issue here with my friend's TJ and I don't see a solution yet.


First, let's get the current setup and all the specs out of the way:

- 2001 Jeep Wrangler TJ with a 5.7 aluminum LS1 sitting on Novak engine mounts, truck accessories and belt spacing, F-Body water pump, AX-15 trans with 3.73 gears and 33" AT tires on a mild lift.
- Engine has a mild truck cam, Novak shorty headers, no cats and free flowing exhaust. Professionally dyno tuned making good N/A power (300ish whp? I don't recall).
- Cooling system consists of a Novak 2 row aluminum radiator, a fan shroud and a Derale P/N 18217 2-speed 17" 2400cfm single puller fan.
- Heater hoses connected to heater core and verified clean and free flowing. New front steam vent pipe connected to radiator under top hose. All hoses new in good condition and coolant system purged of any air. Brand new water pump verified good flowing, new GM 195F thermostat verified working, 2-speed cooling fan activated by PCM, operates as tuned, rotates in proper direction and flowing lots of air.
- Factory hood has been modified with Poison Spyder vents to maximize extraction of engine bay heat. In front of the radiator sits the factory A/C condenser and a small power steering cooler to the side. The grille is factory and all the stock plastic shrouding has been retained. Two KC Daylighters sit in front of grille.

Now onto the driving conditions and overheating issue:

- No issues to report when idling or in stop and go traffic. Driving around town the coolant temperature is perfect.
- No issues cruising at highway speeds (tested upto about 75mph driving continuously for hours).
- BUT driving in heavy sand and mud, or driving steep uphill inclines for more than a couple short minutes or driving in any condition which puts excess load on the vehicle, engine and cooling system and the coolant temperature starts to climb up quickly and go above 240F unless you stop and cool down.

The issue to me seems as if the combination of cooling system components on all our setups (Small-core Novak radiator, small grille opening / frontal area, a single 16~17in fan on most setups) is already working at its limits in normal driving conditions and any additional load situations quickly pushes the system above its cooling capacity.

I currently do not have any input or solutions that are not the typical band aid ones already covered in this thread and unfortunately the Jeep is currently sitting in storage two countries away and is inaccessible due to current travel restrictions,so we can't really try anything until we drive it back home.

If any one has any additional input or solutions to this common issue I'm all ears.

knaffie

One of my friends had his run cooler by installing a mechanical fan. It's loud, but it doesn't overheat anymore. I'm ordering a different OEM fan that moves more air. There's a shop in Indiana that has been swapping in 2.8 Cummins engines into everything and they fought similar issues until they started moving more air with larger fans. The aftermarket has nothing better to offer in a single fan.

LS1 TJ

On my first TJ LS 5.3 swap I used truck FEA and a mechanical fan. TJ 4.0 radiator and shroud. Never had a heating issue.
As I said above it seems so odd the over heating issues. My LS6 is few less ponies than a L92 but the same physical size. More hp more heat?
Could the ac condenser be blocking just enough air flow to cause the over heating problems? I haven't had my TJ in any high load high rpm situations, mine is truly a mall crawler and my winter time snow plow. My transmission cooler is in the radiator no external.
Do you think turning the fan or fans at a lower speed would help? My fan comes on at 205 degrees and off at 197. Stock 197 thermostat. It does cycle on off a bit but it's never failed in over 10 years.
I haven't looked into it but are there "high flow" water pumps that are more efficient that might help?
Just looked at my TJ and the Novak radiator takes up most of the grille space. If you mounted the radiator from the top and bottom instead of the stock side mounts you could gain about 2" of radiator width on the passenger side. Thickness wise there is about 1"-1.5" before the fan hits the water pump pulley. So maybe a custom 3 core radiator?
Just throwing out ideas because I have a L92 on the engine stand and I'm considering a new TJ Rubicon swap. I'd like to retain the AC if it doesn't cause over heating problems.

Michael Yount

iTrader: (1)

Q8 -- What is the size (L" x W") of the radiator CORE? Sounds to me like you need either more fan or more radiator - or both.

Q8y_drifter

Assuming the fins are straight and clean, I doubt the AC condenser would cause any airflow issues.

As for the fan settings we currently have the low speed operating at just above the t-stat opening temperature, which is lower than factory GM. It helps overall but does little to combat high load situations.

Current plan of action is to change the FEAD from truck to corvette spacing to gain additional clearance (~3 inches or so) and then try a bigger fan and vented shroud. Haven't managed to find anything specific yet but will do. The Novak radiator appears to be the biggest/thickest available so for now that will remain as is. We have also purchased a 160F tstat which we will be installing as well as re-tuning the fan settings a little lower than before to give us a bigger buffer zone.

Q8y_drifter

I'm not 100% sure but I've seen 17" x 18" core dimensions mentioned here before and that sounds about right. I agree that the radiator and fan setup are on the small side. That's my conclusion with this swap. Works fine for daily driving low load duties but not for the purposes and environments which the Jeep was designed for unfortunately.

EDIT: Assuming the above radiator core dimensions are correct, I might just be able to squeeze a Taurus 3.8 cooling fan with enough trimming of the Taurus fan shroud. This should improve airflow by quite a bit especially with the thick 3-inch core on the Novak radiator. I will also have to run a standalone fan controller like a Dakota Digital since the Taurus fan requires the low speed signal to be off before high speed kicks. This is all dependent on running a shorter FEAD.

Q8y_drifter

Picture of the engine bay below if anyone is curious. Many layout changes were made since then but the radiator and fan setup is the same.

bobcratch

yikes. That rad is small. A few things you can try before making radical changes to the rad setup. might help if all you need is a few extra % of cooling capacity

-run 75/25 water/coolant. Water cools a little bit better than ethelyne glycol. This will lower the boiling point and raise the freeze point though, so mind that before you try it
-add a pressurize de-aeration (surge) tank - see the diagram here - http://www.billavista.com/tech/Artic...20numbered.jpg the continuous de-aeration provided by this can significantly improve the performance of your cooling system, if bleeding is a problem.
-looks like your steam vent actually runs down, then back up? hard to tell from the pic, but if you could make it not do that it might work better
-also " Two KC Daylighters sit in front of grille." Just for giggles, i would take them off and try a hill on the interstate again. depending on how big and what they look like, that could significantly change the airflow over the rad

just a few thoughts, good luck and i hope you get it sorted out soon!

Q8y_drifter

Thanks for the input!

- We ran all kinds of coolant/distilled water mixes with little to no effect unfortunately. Currently has something in the 70/30 range of water/coolant mix.
- A pressurized coolant tank was a consideration we had in mind which we'll have to revisit and try implementing. Unfortunately the cramped engine bay does not make this easy but hopefully it helps.
- Steam vent runs parallel and goes upwards slightly to the radiator port. No venting or air bubble issues there.
- We temporarily removed the fogs but unfortunately made no difference in low speed heavy load situations. The fogs are mounted a few inches ahead of the grille so the fan has no problem pulling in air from around the fogs.

Michael Yount

iTrader: (1)

If 17x18 is correct -- I think you're going to struggle with that under load.

Also, does this vehicle have any kind of air block or "splash shield" (misnomer) below the radiator? Those devices are there to create an area of low pressure behind/below the radiator to help aid in air flow across the radiator at speed. The old Fox body Mustangs had a black plastic air dam that sat well back of the bumper cover almost underneath the radiator. They were known for getting knocked off or just being removed on lowered cars. Symptom that usually followed was a thread with a title "why does my car overheat on the highway?"

edit - sometimes with a limited core size because of sheet metal, etc., the tendency is to go with a thicker radiator - 3 row, 4 row, etc. That is a less effective approach than most think it will be. As the ambient air picks up heat crossing the first row, the air temp delta it has to work with is continually decreasing as you move across the rad. So the 3rd and 4th rows don't do much. The numbers I've seen go something like this and let's use 17x18 as an example -- call it 300 sq inches of core area. If you double that to 600 sq inches (24 x 25) you get twice (or 100% more) the heat rejection capability. If you go from a 1-row 17x18 to a 2-row - you only get 50% more capability. Adding a 3rd row gives you 25% more on top of that. Adding a 4th row - 10% more on top of that. Probably not an option in this case anyway as I think you're limited on room that way - but perhaps it will help someone who's scratching their head over a similar dilemma.