Overheating issues

[red87]

Hey all,

I just got back from a fun weekend trip up to monache meadows via Sherman pass trail. Trip was awesome except I started having some serious issues staying cool on the trail. I have never had a problem before this weekend. For much of the way back, I had to run my heater on full blast to keep it from overheating, even though I was on an easy trail. I had to watch the gauge and run the heater on the pavement on the way home and my gauge skyrocketed when I parked. I'm not sure what the problem it. My fan is blowing so I know it isn't that. I'm thinking maybe thermostat and fresh coolant. What do you folks think?

 

[tatuedrednek]

I recently had the exact opposite problem on my Cherokee. It did fine on the trail but would overheat on the highway. Curious if yer rig has a fan clutch. That turned out to be the problem with my Jeep. If it does, you will hear the fan make a ton of noise moving air when you first start the thing. That and a t-stat would be my first guess.

 

[off-roader]

To check if your engine fan clutch is working, simply shut down the engine after it's been properly warmed up and while looking at your fan. It should come to an almost immediate halt. If it doesn't, then the clutch (viscous coupling part) has failed.

Alternatively, if you have an Automatic Transmission it could have been heating up and since it's cooled primarily by your coolant radiator, it could in turn have made it look like your engine is overheating. You need to check your AT temps to confirm this.

If that was it, then one thing you may try doing is wiring your AC fan so you can turn it on at the flick of a switch or alternatively disconnecting your AC so that when you turn it on, only the fan activates while the AC remains off. When you are done wheeling, simply reconnect and you have AC again.

 

[red87]

Yeah, the fan has one of those thermocouple thingys. I know that's the wrong name but hopefully someone can step in and correct me

 

[off-roader]

I just updated my post mentioning the main engine fan's Clutch. I suspect that's what you're talking about?

 

[red87]

I just updated my post mentioning the main engine fan's Clutch. I suspect that's what you're talking about?

Yes indeed

 

[red87]

To check if your engine fan clutch is working, simply shut down the engine after it's been properly warmed up and while looking at your fan. It should come to an almost immediate halt. If it doesn't, then the clutch (viscous coupling part) has failed.

Alternatively, if you have an Automatic Transmission it could have been heating up and since it's cooled primarily by your coolant radiator, it could in turn have made it look like your engine is overheating. You need to check your AT temps to confirm this.

If that was it, then one thing you may try doing is wiring your AC fan so you can turn it on at the flick of a switch or alternatively disconnecting your AC so that when you turn it on, only the fan activates while the AC remains off. When you are done wheeling, simply reconnect and you have AC again.

Problem is, I like having AC when I wheel. Call me a baby but it's hot here, haha.

I also thought these trucks had an external trans cooler up front, by the oil cooler

 

[off-roader]

Problem is, I like having AC when I wheel. Call me a baby but it's hot here, haha.

I also thought these trucks had an external trans cooler up front, by the oil cooler

Don't get me wrong, I like my AC too but sometimes it's 110 out when you're driving off road and uphill and slow. Only so much heat your radiator can dissipate in those situation.

Solution? Assuming radiator's good, add another row to the core. Alternatively if needed, rod the radiator to clear the calcium deposits from inside the core. Much more effective than a simple flush and not as costly as a recore/extra row.

They do have an extra transmission cooler but heat's heat. You heat up the air going into the main radiator with the transmission and oil coolers.

 

[red87]

Is this a common issue with our rigs or no?

 

[off-roader]

Is this a common issue with our rigs or no?

It's a common issue with a lot of rigs, not just mitsu's. It's why the aftermarket radiator market is doing well.

 

[red87]

It's a common issue with a lot of rigs, not just mitsu's. It's why the aftermarket radiator market is doing well.

Ha, fair enough.

I'll start looking into these ideas things next week when I have some time.

 

[m3at333hp]

Speaking of overheating issues, I have a question:

My A/T light comes on while wheeling, and it is not low or anything. I have just recently done a flush and use Mobil1. I should note, it did this before the flush also in Cleghorn. It only comes on while wheeling. So, could a filter cause this (even though it is just a mesh filter)? I doubt a clog in the tranny cooler since the oil is not that thick. Bad torque converter? Bad sensor? I will check if oil has turned brown tonight.

 

[off-roader]

Speaking of overheating issues, I have a question:

My A/T light comes on while wheeling, and it is not low or anything. I have just recently done a flush and use Mobil1. I should note, it did this before the flush also in Cleghorn. It only comes on while wheeling. So, could a filter cause this (even though it is just a mesh filter)? I doubt a clog in the tranny cooler since the oil is not that thick. Bad torque converter? Bad sensor? I will check if oil has turned brown tonight.

I'd send a sample of the oil off for analysis just to be 110% sure it's not harming your transmission. But that said, it's likely due to the hot temps and reduced airflow at slow speeds. Have you done the AC fan mod to allow you to turn it on w/out running the AC so it allows you to better cool your fluids?

 

[mike5]

The timing on this thread is perfect. I can add some light to these two questions. So a couple of months ago, I went Coyote Flats in the Eastern Sierras. We ended up around 10,000 feet. When we went the weather was cold (probably around 50 during the day and down to 25 at night). While on a slow/long/steep ascend my coolant temp started rising and my AT light came on. So I pulled over and gave the car a break. Later on while stationary after some slow 4low stuff, again it started climbing.

I had serviced the cooling system so I was a bit surprised. It never happened to me on the streets. But something I'd notice occasionally was stains on the expansion tank...meaning some fluid and over flowed. After my trip, I had the mechanic go through the cooling system. The issue was the thermostat. It was "sticking." But they only figured this out by removing it and testing in hot water. After changing it, I went on another trip with a lot of climbing in 85+ weather. No a single cooling issue. In my case I knew the radiator was good, it had been flushed, cracked fan replaced and coolant drained. So not hard to figure that one out.

With respect to the AT light, my educated guess is this: at higher elevation while off roading and very slow speeds, if you leave the car in drive it will usually use a higher gear than it should. This results in more torque converter slippage (by design) which generates heat. Instead if you deliberately use 1st and 2nd gear, then slippage is eliminated which reduces heat. On trips where I've done this, I had zero issues.

 

[red87]

Sticking thermostat was my best guess too. Hopefully I'll find some time next week to test it. That AC fan mod is a good idea though. I do have an unused switch now that I am on OME suspension...