coolant leak and O-ring
 

I think I have coolant leak by O-ring where the water pump is connected to the tube going to the back. Do I need to take off timing belt and water pump to get to it or can I just take off plenum to replace the O-ring? I have 2000 Montero Sport XLS 3.0.

Sorry but your diving in kind of deep to replace this.

There are several 0-rings.
Posts 80 and 82 show the o-ring at the back of the water pump
https://mitsubishiforum.com/forum/mi...l-48920/page8/
https://mitsubishiforum.com/forum/mi...l-48920/page9/

Post 88 shows the pipe with 0-ring to back of pump below the plenum
https://mitsubishiforum.com/forum/mi...l-48920/page9/

Post 110 shows the crossover pipe which also has o-rings
https://mitsubishiforum.com/forum/mi...-48920/page11/

Sounds like your leak is at the water pipe to the back of the pump.I think if you pull the plenum and the intake then you can remove the water pipe to replace the o-ring and leave the timing belt alone. See Post 83 last picture which shows how the water pipe is attached at the rear of the engine.
https://mitsubishiforum.com/forum/mi...l-48920/page9/

Good luck!

HEy there man, i know its an old post, did you ever get to change the oring going from the top of the engine? Was the oring the problem? I have the same problem wondering if is possible to avoid removing all belts.

Thanks in advance!

You do not need to touch the belts at all, but all the inlet manifolds need to come off to get access, which is a big job as there are a lot of multi length bolts that hold it on.

Thank you
 

Thanks man, was just waiting for confirmation to start, i have to say is much better than removing belts... Hopefully is only the oring what is bad there, one can see the green blood over the block. Cheers and thanks again.
https://cimg8.ibsrv.net/gimg/mitsubi...286d8a7768.jpg

Figuring out a similar leak issue, after replacing the water pump and noticing coolant pooling on top of the block and dripping down the transmission. Removed the Plenum and manifold to get access to the water pipe, which is pretty easy and straightforward, not that big of a deal. Following the FSM steps but can't seem to get the water pipe to seal to the water pump. Is it a bad idea to put gasket sealer around the pipe? It seemed like someone had done that on the old WP.

I just did this job also, i can say the pipe had no sign of dripping coolant, but as you can see from the picture, looks like in mine the coolant is dripping from the head gasket... At least thats what i can see, i reasembled all back again with new gaskets, and still have coolant leaking same place, above the transmission ans some infront of engine, my suggestion for anybody with this issue is to insert a camera to that area of the engine when the engine is running, and check where the coolant leaks, interesting thing about my issue it only leaks when i turn off the engine, and not when is running. My 2 cents.

https://cimg3.ibsrv.net/gimg/mitsubi...0e039f8e24.jpg

We have very different shaped coolant passages. I have the 6G72 3.0L, so older engine but same concept.

Mine was 100% coming from the water pipe as the end is a little corroded and was not fitting snugly. But I could see how you get the same issue if it leaks from one of the front two coolant passageways. I noticed on mine that the coolant was pooling under the water pipe flange, then running down the top of the engine and off the transmission like a gutter.

My solution is by no means the correct way (replacing the pipe), but it worked. I put the old o-ring behind the new o-ring with a bead of gasket sealer in between so I could fill the voids and get a water-tight seal. Been cruising around for a week with no leaks.

https://cimg7.ibsrv.net/gimg/mitsubi...13d665a5bf.png
https://cimg9.ibsrv.net/gimg/mitsubi...3e3e785b2d.png
https://cimg1.ibsrv.net/gimg/mitsubi...1efa640a46.png

That is a very nice solution, ill try to get a camera to that area and let the engine run to see where exactlly the leak is, when i check that pipe area in mine was no signs of leak there but could be same situation. I was noticing your gaskets, mine was using metal gaskets for the intake, also the gasket kit i got was metal ones, i didnt use any sealant, do you know id is better to use some?
https://cimg0.ibsrv.net/gimg/mitsubi...fd0f31ba1c.jpg