Hi, This is my first post here but I have been lurking around for a bit. This forum is full of great information.

I have a 1998 5.9 Grand Cherokee and my questions are about keeping the 46RE cool off road.

I overheated the trans while I was 3 hours up into the mountains on a steep climb about 5 months ago which prompted me to add an additional transmission cooler in front of the condenser plus a temperature gauge and a change of underwear.

The temp sender is plumbed into a T in the hot line going into the cooler so I can see how hot my oil gets and prevent it from sheering. It is a Hayden HD tube and fin rated for 23000 GVW. I originally had it running throught the radiator cooler then the Hayden and back to the trans but I recently bypassed the radiator and now the transmission lines are running only through the Hayden. The reason I did this was because a friend of mine had his radiator rupture inside the trans cooler portion and ruin his transmission.

Yesterday I went out into the desert to check out an abandoned cabin near the Carol Lombard crash site and there is a 3 mile rocky grade we traversed and the transmission oil temp reached 250 towards the end. It may have gotten hotter because my trans temp gauge only goes to 250. The temp outside was around 84* and sunny and we were moving about 2-3 mph. It was hanging around 190- 200 for the most part prior to that in the flat areas which is around what the motor temp stays at.

How can I get this hot side oil temp to stay lower? Could my E fan not be pulling enough air over the cooler at these low speeds to cool it efficiently?

I also was not in 4lo. Would putting in 4lo made a noticeable difference in the oil temp coming out of the converter?

I am looking at different styles of coolers now and I would like to have one with a fan on it but I only have a couple of inches to work with behind the grill. I would have to get creative with mounting options.

The Hayden is mounted to the right side of the condenser I am going to move it to the center to see if it gets more air across it.

Would a plate and fin style cooler be a better choice? I know they are smaller and rated more GVW's.

Thanks,

Mike

 

Probably need a bigger cooler. And the fin style is better than tube. Anyway. here's this. You probably don't want to see it.

 

The cooler I have is a tube and fin. What do you mean by just fin? Are you talking about stacked plate?

No offense but I think that chart may be a bit outdated. ATF-4 is rated for about 300* before it starts to degrade. Also that chart is for internal transmission temps. I am only measuring the oil temp after the TC where is gets the hottest. It's much cooler inside the transmission before the TC. If my trans had gotten to 250* then there would be a problem. ATF-4 reaching that number isn't a problem. I just want it cooler so I have more wiggle room when I'm off road where temps reach 115* or more.

 

Your e-fan only runs when engine coolant is hot enough to warrant it, so, there are probably times when it isn't doing anything at all for the trans....

You could mount a fan to the front of the trans cooler (pusher), and that would help.... crawling in 4Lo would more than likely also reduce the load on the trans. Regearing the diffs wouldn't hurt either.

What size tires, and what gear ratio are you running currently?

 

Sorry I forgot to fill that out. It's nothing big, I have a 2" puck lift and 245x75 16 tires with 3:73 gears. Nothing crazy, I still use it as a DD. I was looking for a sort of beater that I could cut into but I found this 5.9 in great shape and low miles so I am reluctant to start cutting sheet metal.

I really like the idea of putting a fan in there on top of the cooler but it just won't fit. I'm going to have to locate a safe spot with some more room. This motor and everything in the engine compartment was shoehorned in there. You can't even check the oil without bumping something. I wonder it I turned on the ac that it would kick the fan into high and cool it more.
Thanks for the replies. The only things I can think to do are to get a better cooler and or somehow make room for a fan.

On a side note, I did find this late model Dodge 1500 with the 318 that somebody rolled off the cliff of this old volcano! It was being held there on the edge by a couple of large boulders. The interior was stripped and the tires and rims were gone. I am still puzzled over that. I climbed down and took the alternator and throttle body. Everything looked clean and preserved. I wanted the intake and valve covers but it would have been crazy trying to get those up the cliff.

 

They make various size coolers that come with a fan, that you can mount wherever you can find the space.... or, you can simply do the same thing to yours. They even make thermo-controls for them.... (which you can also do yourself without too much trouble.) Plumbing thru the radiator first, and then the aux cooler is actually more efficient...... the in-radiator coolers rarely fail. (but yes, it DOES happen.....)

Tires vs. gears is actually pretty good for you. 4Lo would probably still help though. (so long as the trans isn't limited to first or second gear, simply because you are in Lo range..... I don't think the jeep does that trick though.)

Truck had been there a while huh? Any gas left??

 

Haha we didn't check. To get to the rear of the truck would have been suicidal and I hate heights! No the 4lo doesn't lock it in 1st. Although we could only go about 2-3 mph tops on that trail. It was filled with softball and volleyball sized rocks. Terribly annoying. I want to get the fan and wire it to come on at 180* or so. I will probably get a thinner nicer stacked plate/ fin cooler with a thermostat. I hear those allow more airflow. Thanks for the suggestions.

 

Ok well I did some measuring and my cooler is .75" thick and with removing part of a brace and a piece of header I can fit a 2" thick fan on top of it. I saw a 6" x 2" thick fan someplace online but can't find it now.

 

Here's a 5 inch.....

 

That is exactly what I need! They get more and more expensive the smaller they get. None the less that's it. thanks a lot. I have been sitting here searching so long I'm getting the evil eye from the wife lol.