Hey everybody! I'm fresh to the forum here and am stoked I found it. I'm really out of the loop on what support there is out there for me and my truck so I'm wicked happy I found this.

Aside from that, here's what's goin on: I've got a '90 V6 that I love to damn pieces. The truck is a tank, a representation of true, tough, durable crafstmanship. He's gotten me through everything and anything, even when there's been problems. Now, I like to do all the repairs myself. I don't want to pay anybody if I don't have to, obviously. I'm going to be taking him on a cross-country road trip from California back home to Maine. But the latest and greatest problem has hinted that it's there and not going away.

Essentially, when I'm driving on the highway and come to a stop, either in traffic or exiting to drive city streets here, the temperature gauge starts to rise. Usually, it sits a nice 1/8 of an inch or so above the first yellow rectangle. When it gets to the top of the second one, I rev it to about 3000 rpm which then cools the engine off and then everything is ok, if I start driving, traffic-permitting of course... My intuition is leaning towards a water pump issue.

Here's what I've done prior to this issue to help alleviate some of the stress:

1) replaced the original radiator
2) replaced the hoses
3) replaced the thermostat
4) flushed the system

Now, I noticed that when I parked the truck, the reservoir, which was full at the beginning of the trip, was bone dry. Unfortunately, I have neglected to check if the reservoir filled back up any as work tends to distract me quite a bit, but I doubt it has. I have seen a pool of coolant before in the skid plate, dripping from the block close to the water pump. I want to say that the seals have gone and that the water pump might be rusted internally because I know the system was full of rusty crud. But I really cannot say for sure. I don't want to buy parts that I may not necessarily need.

ANY ADVICE OR TIPS OR KNOWLEDGE? Thanks!

Hey vegatank6,

Welcome to the forum and count yourself lucky to have a montero. It's one of the most underrated 4x4s in this part of the world.


I am more inclined to think you may have a bad mechanical clutch on your fan since you are only getting warm at slow speeds/stopped. Its a viscous fan. when engine bay is hot, the fluid thickens somehow and the fan will have some good resistance in turning. Spin with your hand, it should stop no more than 1/4th turn after you take your hand off it.
When engine is cold, the fan will have less resistance and spin more freely.

If you haven't done so already, go to mitsubishilinks.com and get yoyrself a copy of the FSM. You will find the exact test procedure for the fan.

If it does require replacement, I don't recall it being very expensive, < $50, when I had to buy one from auto parts place. Check rockauto.com as well.

Good luck.

Depending on the number of miles on the truck, it might be about time to replace the timing belt. Replace the water pump at the same time.

Hey 90rustymontero! First off, I appreciate your response! Definitely gives me something to look at, WHICH I DID! And basically, completely cold, sitting for a day, the fan was hard to turn. It didn't free flow at all. AND, the reservoir was still empty as well as the radiator being low, at least when you look at it from above... It's got 205,000 on it and I hope the head gasket isn't going... Where could all the coolant be going? I didn't notice any puddles underneath the truck...

That's what my thought was. When it starts up, it ticks for a minute or so and it's a bit shaky. Even just a regular idle it jiggles a little here and there. Kinda sporadically

It was early when I read your post, didn't even see the talk about the leaking coolant. I'd replace the water pump as part of a timing belt job. It's probably leaking from where the tube that runs between the heads connects into back of water pump, theres a little o-ring seal that goes in there.

When this happens there's usually a small puddle underneath back by the transmission as the coolant has no place else to go once it's caught in the V between the cylinder heads.

Ahhhh gotcha. That makes sense. I had a feeling. I'm going to replace the fan clutch as well and I'll get back to you on the result. I really appreciate the help here!

I will look for it. I really appreciate the info! I'll get back as to what the result is after I do the work

Check the radiator cap also. I had one that didn't seal any more and the coolant would steam out past the seal once it got hot. It took me forever to figure out where the coolant was going.