5.3 solution for overheating on highway please help!
Thread Starter
Teching In
Joined: Feb 2009
Posts: 4
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5.3 solution for overheating on highway please help! I have been searching and trying to find an answer for this on multiple sites, but no luck. I have had the swap done for over a year and a half now, but every time I drive on the highway in excess of 65 when its 110 out the thing will get to 250 degrees, as verified by the dash gauge and the GM PCM. As soon as I pull onto the side of the road it quickly cools down to about 220 within a minute.
I I will add after a night of wheeling driving home at 70 or so the temps will not go over 215. I can crawl around all day at the mall and it doesn't get over 210 as well.
And all the basics have been covered, new water pump, new 195 t-stat, its not running lean, no air in the system......etc.
Some specs, 2001 TJ with 2002 5.3, 4l65e, Novak radiator, Novak spal fan with shroud. The fan is controlled by the pcm, but of course on the highway with the temps staying so high the fan never shuts off.
It has to be down to a airflow problem at speed interfering with the running fan. I even tried a new shroud that Novak sent me with 4 trap doors on it, and driving it without the winch on but still no luck. So has anyone tried installing a switch that will shut the fan off while going down the highway, or do you think that will even work? I'm at a loss at this point.
I I will add after a night of wheeling driving home at 70 or so the temps will not go over 215. I can crawl around all day at the mall and it doesn't get over 210 as well.
And all the basics have been covered, new water pump, new 195 t-stat, its not running lean, no air in the system......etc.
Some specs, 2001 TJ with 2002 5.3, 4l65e, Novak radiator, Novak spal fan with shroud. The fan is controlled by the pcm, but of course on the highway with the temps staying so high the fan never shuts off.
It has to be down to a airflow problem at speed interfering with the running fan. I even tried a new shroud that Novak sent me with 4 trap doors on it, and driving it without the winch on but still no luck. So has anyone tried installing a switch that will shut the fan off while going down the highway, or do you think that will even work? I'm at a loss at this point.
Typically cars shut off electric fans once the vehicle goes above 40 to 45mph. Are you missing an air dam? At highway speeds if an air dam is missing that can cause overheating.
The fans should not be running at highway speed it impedes airflow and will cause overheating.
The fans should not be running at highway speed it impedes airflow and will cause overheating.
Thread Starter
Teching In
Joined: Feb 2009
Posts: 4
Likes: 0
Typically cars shut off electric fans once the vehicle goes above 40 to 45mph. Are you missing an air dam? At highway speeds if an air dam is missing that can cause overheating.
The fans should not be running at highway speed it impedes airflow and will cause overheating.
The fans should not be running at highway speed it impedes airflow and will cause overheating.
Also the rad is sealed tightly against the core support.
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On The Tree
Joined: Aug 2012
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Maybe try and pull the fuse to your fans and go on a highway run to eliminate the fans as your problem. Really weird, usually overheating happens in stop and go/slow driving not when there is 60mph airflow (5000+CFM per square foot of radiator) hope you get it figured out.
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I remember awhile back Stu-Cool had this problem on his LS-swapped Stude. I may be wrong, but I think he traced it to the heater core loop in which he was using a blocking type valve to stop flow through the core. This caused no issues around town, but on long uphill pulls the engine would overheat...
