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Modified JK TechTech related bulletin board forum regarding subjects such as suspension, tires & wheels, steering, bumpers, skid plates, drive train, cages, on-board air and other useful modifications that will help improve the performance and protection of your Jeep JK Wrangler (Rubicon, Sahara, Unlimited and X) on the trail.
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I thought I'd chime in here as I have had similar issues here in Phoenix. My '14 JKUR has 35s w/ 4.88s, steel bumpers front and rear plus RSE steps. Climbing out of Phoenix to Payson or Flagstaff during the summer always makes me nervous. Some of the grades can be several miles and they're decently steep and when it's 110 degrees outside, I've hit 245* while pulling my ~2k lbs. trailer. I will turn off the a/c and blast the heat with the windows down to help now. It gets hot whether I'm pulling the trailer or not. I've never ever overheated, but I don't want to be the guy on the side of the road with small kids and a dog trying to figure out what to do when it's blazing hot outside. I will say that several weeks ago, we drove to Payson for a camping trip and the second I pulled in to town limits, my CEL started flashing and it was running like shit. I scanned it and it was a cylinder 2 misfire plus an open circuit on injector 2. I had it towed to the dealer and they said my cylinder head was cracked and needed to be replaced. Because of the cracked cylinder head issues in previous years, they called Chrysler and were able to get it mostly covered. I've since gotten it back and it still runs the same even though I was hoping that could have been part of the problem. I just think these engines run hot and the additional load that we end up putting on them with tires, weight, restricted airflow to the radiator only exacerbates the issue.
Who said it was the bumper and winch and everything in front restricting airflow.....you were right (knock on wood).
took the bumper off and drove around up the mountains and up grades on the freeway at 75/80 and hottest it got was 225-230.
Who said it was the bumper and winch and everything in front restricting airflow.....you were right (knock on wood).
took the bumper off and drove around up the mountains and up grades on the freeway at 75/80 and hottest it got was 225-230.
It's interesting to see that direct comparison. Depressing at the same time since I am not negotiable on bumper/winch combination . Griffen seems to be helping my situation for the time being, but I suspect if I did what you tired I'd probably see cooler normal operating temps.
Here's a trick I came up with to check the thermostat opening temperature against the engine coolant sensor. It won't necessarily tell you which one is in error, but if they agree, chances are that the temp sensor, and at least the thermostat opening temperature are correct.
First step is find the spec for the tstat opening temperature, which looks like 203F (ref motorad cut sheet).
With a cold engine, startup, let it idle, and watch the engine coolant temperature digital readout (use a scan tool for OBDII engines without a digital dash readout like the 3.8L Jeep). When the tstat initially opens, cold water (from a cold radiator) will rush in and the temperature will drop a few degress. For example, at 204F (increasing) the temp suddenly decreases to 197F -- that's when the tstat opened and let in the cold water, which would be about perfect in this case.
Thanks for sharing!
My brother had a similar problem some time ago. Probably he still hasn't found any solution. Maybe it will help.
It's nice to see that some older threads still add some value to people searching and reading. I guess I'm 1 year into my Griffin. My feelings are still about the same and that air flow restriction to the rad is the biggest issue most of us have. I'll be keeping a close eye on things as summer heats up again. I just completed a ~3k mile trip up through Moab and Colorado towing my little overland trailer. When I know I'm going to be going over passes or really revving that engine I just use my tuner to turn the fan on high and leave it on. That really seems to help keep things cooler. If I don't have it on high I'll will see the coolant temp rise up there towards 240*.
Last edited by resharp001; 07-19-2021 at 10:42 AM.
Russ one of the biggest cooling issues people can have is that airflow bypasses the radiator. What I mean is that the fan to rad seal should be 100% so that all air going in through the rad ends up passing through the fan. When I adapted the SS Camaro fan to my Jeep rad I spent lots of hours doing that with custom made plates and 1/2 square HD foam seal. Paid off because even crawling/climbing a steep hill offroad in 100F heat it does not over heat and that is a Jeep rad cooling a Chev V8. Most I ever hear the fan is about 20% speed. Someone asked about changing the setpoint temperature - this can be done with programs like HP Tuners (there are others) and it is simple. You change the thermostat down to around 195-200 and state in the program what the thermostat is. Then there are multi-levels of fan setpoints that you simply revise to lower temps. I know that will give a 3.6 Pentastar more power as they pull timing back to 24 degrees due to impending detonation from high temps (pollution thing) right at the moment where the more timing the better.
Russ one of the biggest cooling issues people can have is that airflow bypasses the radiator. What I mean is that the fan to rad seal should be 100% so that all air going in through the rad ends up passing through the fan. When I adapted the SS Camaro fan to my Jeep rad I spent lots of hours doing that with custom made plates and 1/2 square HD foam seal. Paid off because even crawling/climbing a steep hill offroad in 100F heat it does not over heat and that is a Jeep rad cooling a Chev V8. Most I ever hear the fan is about 20% speed. Someone asked about changing the setpoint temperature - this can be done with programs like HP Tuners (there are others) and it is simple. You change the thermostat down to around 195-200 and state in the program what the thermostat is. Then there are multi-levels of fan setpoints that you simply revise to lower temps. I know that will give a 3.6 Pentastar more power as they pull timing back to 24 degrees due to impending detonation from high temps (pollution thing) right at the moment where the more timing the better.
Do you have a couple pictures of what you did? The things I have in front of my rad just are what they are in general and not changing. I know you're a proponent of the HP Tuner, but I'm also at a stage 8.5yrs in that I'm less likely to dumb another several hundred of the HP when I have both my Bully Dog and Jscan. What you say about the bypassing makes a lot of sense though. On this 4k mile trip I just too pulling my trailer over many passes, if I had that fan on high I'd hardly see the temps creep up whereas if the fan wasn't on high they would just as I'd expect. There's no doubt that having that fan draw the air back really helps. My issue is that with the Bully Dog I have to turn it on high every time the ignition cycles. I will say that in Tx when it gets up over 100° it seems my temps will still creep up even with the fan on high. I'd bet really ensuring all the airflow is making it over the rad would help somewhat though.
I am not sure if BD/JScan can do what I talked about in couple posts back. What I am referring to is the attached screenshot of HPT for a 3.8 Jeep which of course is non-functional because of my Chev install which runs on its own ECU. But the ideas are there and these are access to the code setpoints right in the ECU which I am not sure if the BD or JSCan will allow similar access. But the important thing is to change the TStat to the desired temperature first then go into the program and match the tstat rating then make the fan settings.
I do not have great pictures but the suggestion is to investigate if air is bypassing the rad or the fan. What I suggest is to start with the entrance to the rad from the front of the vehicle. Place a very bright light inside the engine bay near the rad tanks sides where it attaches to the front support (do once for each side) and see how much light you can see outside with the hood closed and at night of course. Even siliconing small gaps helps immensely. Once you are happy with as many gaps sealed as you can you need to see if there is air turbulence outside the grill. Best way to do that is the same way they fixed the aero's on the 1964 GT40 for LeMans. Use bits of wool or string on the outside across the bumper on top of the winch etc and see if you can get your hands on a Go Pro, mount at the front looking across all the strings and go for a drive. That will tell you if the air is disrupted. Last thing is to inspect all the gaps around the fan frame to rad mount and ensure all the gaps are filled. the light works here too and in the dark of course. Again fill the gaps with sealer that is easier to remove should you need to change parts. Larger gaps in mine I used 1/2" x 1/2 or 3/8" High Density foam tape sticky on one side but use silicone to hold it in place. Was your Griffin rad the same shape as the factory unit? Try those things and let us know if there were gaps. I fixed a friend's kitbuilt floatplane once using similar theories as he had crappy airflow past the cylinder heads and they were getting to 450F (max temp) in climb. When we were done it never got over 280 in same climb. He was ecstatic. Guy who built the plane was not the best for these things.
Hope this all helps
07-29-2020, 07:15 AM
. Griffen seems to be helping my situation for the time being, but I suspect if I did what you tired I'd probably see cooler normal operating temps.
