That is all great input. That write up was super helpful. Didn't get to pick up the filter until tonight and then had to mow (5 acres of grass), so I couldn't swing the tranny job tonight. I will be in the North country tomorrow so I'm planning to tackle this Sunday. If not, I'll take Monday off and make it happen. I'll post pictures once the pan is dropped. Hopefully the filter is hopelessly clogged and it's nothing worse. Not that that would be a good thing...

Okay, I found a few minutes tonight to mess around with the Montero. I pulled the transmission line as suggested, put the truck into neutral and ran for about 10 seconds. The photo shows the results. I'm not sure how much flow there should be, but it seems to be moving adequately. That said, I'm not a transmission expert, but this fluid looks pretty bad. Are there any insights to be had into my overheating issue from this?

From the looks of it, that's terrible. Hydraulic systems usually stay very clean, so I'd say something's gone wrong in there. Did you give the fluid a whiff? If it smells burnt, it is.

John B.

+1 on what Johnny said. Transmission fluid should be red, not brown. Hopefully a fluid and filter change will help with the problem and not cause more issues. Transmissions that have lived with the same fluid for many years become happy with it, and changing to new fluid can cause additional problems. The high detergent in the new fluid tends to clean the inside of the transmission, and while I don't know the exact reason for it, I've seen it cause problems on more than one vehicle with fluid as bad as yours is. Typically in a case like yours it would be wise to not change all the fluid at once, but to drain and replace a quart or two at a time over the course of several months so you don't shock the transmission. As weird as it sounds, I'd reuse about half of that nasty old fluid that you removed, replace the rest of it with Diamond SPIII compatible fluid, and drive it with my fingers crossed and lucky rabbit's foot dangling from the rear view mirror.

I've resolved to replace the tranny. It overheats too bad to drive and I don't want to run $120 in transmission fluid through it and waste a transmission fluid just to find out it doesn't fix anything. I found a used tranny for $350. I'm going to try to pick it up this weekend. That is, unless anyone wants a Montero with a nice body and bad tranny for $2k...

That sounds like a good choice. I'd pull off the pan and check the inside of the new trans before you buy it - it should be nice and shiny clean. Make sure you reverse flush out the transmission coolers and lines before you hook them up to your new transmission.

Okay, I went ahead and pulled the pan, changed the filter and flushed the trans fluid. The replacement transmission is 4 hours away so I figured, what the heck.

So, I test drove it and the AT light is still flashing... My driveway is 1/2 mile long. The AT light is coming on after I drive down the driveway, turn around and get about 2/3 of the way back. I can turn the ignition off, start the truck, and the AT light goes away. If I drive it down the driveway again, it comes on at exactly the same time, every time. Also, the front wheels on the 4x4 indicator are now flashing continuously as well...

I bought a non-contact thermometer and after letting the truck idle until warmed up and then driving up and down the driveway twice (2 miles) with the AT light flashing I checked the temperature on the trans. pan and it's about 145 F.

According to the service manual the temp sensor should have continuity at 289 - 304 F. With the exterior of the pan at 145, it seems impossible that the internal oil temperature is that high...

Thoughts? Maybe the TCM?

The ATF was pretty dark and the filter had some particulates in it, but not totally clogged. The pan magnets had a fair amount of pretty fine metallic residue on them.

By the way, I hope the Mitsubishi engineers added an exterior trans filter in later iterations. removing the oil pan was a PITA.

That makes it sound more like a bad trans temp sensor, or a problem with it's wiring.

Replaced the fuel pump today. While doing so, unplugged the battery for about an hour. Once everything was back together, not only was the truck running great, but the trans light is not coming back on. Pretty cool. Tomorrow I'm changing the spark plugs (which looks a little ridiculous at this point, what were the engineers thinking?) and changing the oil for the first time.

Also, the truck was leaning to one side and when I was working on the trans I noticed the previous owner had cranked up the torsion bar on one side only (why?!), so I figured, screw it, I'll raise the other one too. So now the truck is even, but the front end is way up. I'm ordering OME springs for the rear, any suggestions on regular or HD? I will be towing a 18' Lund from time to time.

I will also be ordering a set of 33" x 10.5" BFG AT's tonight. Things are looking up.

Things were looking up... The engine hesitation issue did not go away. I gave up and brought it to a shop. It saw with the shop for two days until they called and said they give up and told me to pick it up with no charges...

So we took it to another shop in a different town. It sat there for two days, and at first the tech was confident he was going to have it taken care of, but then we called on an update and he wanted to wash his hands of it. He gave me a list of the scan tool error codes, made some observations I had already made and basically told me he wasn't interested in trying to further diagnose it. Uhg. So, the codes are as follows:

- Code 11 - o2 sensor
- Code 12 - Mass air flow
- Code 14 - TPS
- Code 24 - Vehicle speed sensor
- Code 25 - Baro? (can't read his writing)
He also pointed out that the engine coolant sensor harness pigtail has epoxy on it like someone did a poor repair on it. Also says it needs a "rear axle speed sensor", which I didn't know it had, I assumed the VSS was in the transmission. and that he smoke tested it and saw a small leak on the "tuning valve"...

Help?