I've searched and can't seem to find any info. I want to replace my stock 3.0 V6 tranny cooler with a larger capacity cooler.

Most likely a Hayden as that what's available locally.

What size fits, and any tips to installation.

Not sure about the size but what's wrong with the stock cooler? If the cooling system (both engine & tranny) is maintained, it's more than enough to cool a properly operating Montero.

I'm having the same issues that a number of people have on here. Fine running stock 3.0, but with a non-lockup converter in 90-100+ temps and 75mph+ on the freeway the fluid heats up dramatically, the pre 91 Monteros were never expected to go much above the then 55mph speed limit. Add in rolling hills and you have issues.

Also if I keep the speed down to 65 it never comes on, hit 75 and it a guarantee that it will eventually come on.

So now I need to get a bit more area for cooling. The fact that the light comes on and with 2-3 minutes of idleing will go back out is indictitive of a system design issue, not a parts failure.

I either need a larger cooler, or a smaller one in addition to the stock one.

I think you have other problems. I never had that kind of response in the same temps at the same speeds with a non lockup converter. Are you running throught the radiator and the air/oil coolers? Add that I was running at those speeds, then suddenly sitting still in ATL rush hour traffic, then running those speeds (and higher) again, up and down the local hills and dales, and pulling a trailer with a load. The only time I lit the lights was 4wdhi grunting at low speeds on extreme climbs in very hot weather, way down in the rpm range with almost no air over the cooler/radiator (the engine coolant was getting hot, too).

I'd be flushing my cooler/lines.

I dont agree that the Montero was not designed with speed greater than 55 in mind. I know that has been repeated lots of times, but that does not make it true.

On my Gen1 4 4 cly, when running only the cooler in the radiator I found that punching it on the highway op long grades did get the temp lite on. That was with a motor that makes 240 ft lbs of torque at highway speeds.

I also had a smaller converter. Once I hooked up the auxiliary cooler the unit never overheated. IT still ran too hot..

Factors I would look at.

Taller tires, past 31's add to the problem.

A temp switch that's coming on too early. I never hurts to check the pan temp.

As Eddy pointed out, a partially clogged cooler, either internally or externally.. Perhaps both.

What size tires are you running?

A larger cooler never hurts but it good to make sure you dont have some other problem.

Kevin

I also agree there's another problem.

I have a lockup torque converter behind a 3.0L that's probably putting out at least as much torque as Kevin's turbo - somewhere around 220HP/260lb-ft. I understand the heat-creating sustained highway slip on the non-lockup units due to weight and aerodynamics, but I drive my truck hard in the lower gears where there is no lockup. The additional torque created by the roots blower at low rpm surely puts a lot of slip on the 1-2-3 gears and I often thumb-shift the A/T to avoid the 3-O/D upshift until I'm above 4000rpm. I frequently hold the shift points until 4500rpm on hard acceleration, creating opportunity for heat buildup due to slip and reduced airflow cooling at lower speeds.

Before the blower was installed, I drove the truck (heavily loaded) from SC to Colorado and back..... with 32s.... at speeds consistently above 80mph..... on severe grades.... with a non-lockup transmission. If there was going to be a heat issue, I would have seen it then.

You might pull the temperature switch and check the accuracy. If you've installed a body lift, have you raised the radiator so it gets proper airflow? Are your radiator cooling fins clean? Is your radiator clean internally? Is your complete cooling system in good shape? It may make a difference which way you route fluid through the cooler - have you reversed the hose connections to the cooler?

Frank

I would 2nd that.......
Have you flushed the Tranny?
I would do that and then see what it does.

If you want some info other than "the stock system is the shizznit" refer to this thread:

http://www.4x4wire.com/forums/showflat.p...rue#Post1094678

I don't think anyone is suggesting that the OE cooler arrangement is the best there can be - but it does seem to work just fine at most any speed when everything else is in good shape.

Certainly a larger cooler is an improvement, but what some are suggesting is that a larger cooler that results in lower temperatures may only mask another issue that should/could be corrected. If the issue is one of insufficient airflow or truly overworking the transmission (as in towing), a larger cooler may be a good idea. Otherwise, the "fix" might be accomplished for less time, trouble and money.

Frank <img src="/forums/images/graemlins/cheers.gif" alt="" />

While the stock system is good, it heats up quick when crawling, towing, or long grades. Installing a temp guage has confirmed this for me. Just trying to help the guy out with his original question. I think an Aux cooler is a good idea for those that push their auto trans hard.

But yes first step is to ensure all other parts of the system are good to go. <img src="/forums/images/graemlins/cheers.gif" alt="" />