Coolant leak advice 96 SR (FIXED!)

[KarmannMarco]

Hey guys. I'd like to ask you guys for some advice before I start tearing my engine apart.
For the past year or so I've had the same constant slow coolant leak coming from somewhere on the front or rear of the engine on my truck ( 96 SR , 3.5L Dual Cam )
I've never been able to pin point it and I've never seen it physically drip but coolant spots on the driveway under the back of the engine/bellhousing area and disappearing coolant don't lie.
The coolant loss has been so slow that I've not put much effort into fixing it.
Until last week when on my drive home from Denver about 10 minutes from home I saw my temp gauge start to rise. It never got past halfway the middle and H but it was enough concern for me to pull over and let it cool down rather them forcing it home and possible causing expensive damage.
I popped the hood and observed what was going on. There was steam coming from underneath and back of the intake manifold and the truck was about 1/2 gallon low on coolant.
After a few minutes I topped off the coolant and drove home with no issues and just as I pulled into the driveway it did the same thing.
The obvious problem is that my small leak turned into a good flow of coolant coming out of the engine.

Now I had always assumed the leak came from the "O" ring in the pipe under the intake manifold.
Could you guys suggest every possible likely place coolant could leak from the top and back of the engine?
I'd like to order parts before I tear into the engine and take off the intake manifold.
Part numbers/ links / suggestions / pictures etc... are all welcome.
This was bad timing as I was about to sell this truck at the end of the month and I want to make sure this isn't an issue for the future owner.
Thanks in advance!

 

[JohnnyBfromPeoria]

Probably not heater hoses, right? There are two 3/8" flexible hoses that run to/from the throttle body: possible. There are two 1/4" flexible hoses that are on the front of the engine, but hidden behind the timing belt covers, however, a leak there would not (probably) show up at the rear of the engine. This leaves the coolant pipe that runs through the valley of the V-6, provided it isn't coming from somewhere more serious, like a head. The pipe has o-ring seals at the water pump on the front of the engine and at the back, where it joins...something...kinda foggy on that right now, but I think it connects to the flexible lines I mentioned before. At any rate, you're going to have to remove things to find the leak, and be equipped to replace the flexible hoses in the sizes I mentioned above, 2' of 1/4", 3' of 3/8" and 5' of 5/8" if you want to replace the heater hose with aftermarket. I used silicone hose from siliconehose.com as it was recommended to me by IncorpoRatedX as being the best option for durability. In the course of things, I replaced the metal pipe that runs through the v-valley; I think Mitsubishi is out of them by now, so I hope yours is good. My only source was a single dealership in Miami that was a disaster to deal with, and they were the only ones in the U.S. that had one left - come to think of it, they had three, but that was a year and a half ago from this post date.
Can you see any pooling in the "vee" of the engine?

John B.

 

[Salonika]

Look into putting UV dye in your coolant. This allows you to more easily locate a leak. Just don't wait too long after adding the dye before you start looking for the leak. I'd start by just running it at idle for 10-15 minutes, if you can't see anything then try a little higher RPM, maybe a short drive around a parking lot.....keep increasing drive time with frequent checks until you find it. The sooner the better. Also have a good pitch black dark garage to use the UV light, makes a world of difference. It works. Also you may need to go under the vehicle with the light and shine up along bell housing, sides, etc. I even keep a mirror on a stick handy.

 

[KarmannMarco]

Thanks for the advice guys! John , I cannot see pooling on the engine but with the engine cover on there is almost nos pace to see down there.
I'll tear into it soon and report my findings. Salonika , thanks for the dye Idea. I hadn't even though of it.

 

[KarmannMarco]

Alright , bought all the silicone hose to replace everything on the montero and the "o" ring on the water pipe going across and under the intake manifold.
Spend Monday morning starting to pull the intake manifold and got 90% of the way through it. Tuesday-Wednesday we got about a foot of snow and since my E24 BMW is tucked in the garage for the winter and the Montero is outside I had to wait before finishing the job. Now the snow is melting and its a beautiful 40 degree Colorado sunny day and I was able to finish pulling the intake manifold ( and what a bish it is to get to the back IM bolt and the back bracket bolt )
I pull the manifold off and this is what I see. One of the heater core big pipes on the back of the engine has a HUGE gash in it.
I think this qualifies as a leak spot.
Im going to replace every coolant hose and every vacuum line on this engine.

 

[Salonika]

I'd keep the Mitsu squeeze clamps wherever they are......it might seem nicer / easier to replace them with a different type, but the Mitsu ones never come loose. I prefer the security of those vs anything else, even though they are a pain to work with.

 

[KarmannMarco]

All done! Coolant leak completely stopped. I replaced all accessible vacuum lines , PCV valve and a few other things while I was in there and it now runs and drives like a dream.
That intake manifold was such a pain in the *** but now I could easily do it in half the time (not that id want to)

 

[snare]

Glad to hear ! All coolant/heater hoses replaced with silicone?

 

[JohnnyBfromPeoria]

So let's review. The leak was coming from a coolant-carrying HOSE, not a pipe (which in my mind would be metal), right?

John B.

 

[KarmannMarco]

Yep , the leak came from the hose on the right. Not the metal pipe. I went ahead and replaced both hoses while I was in there anyways with silicone hose from siliconhose.com Nice quality stuff by the way.

 

[JohnnyBfromPeoria]

I assume you meant these guys: https://www.siliconehose.com/ as you left out the "e" in silicone and the link you posted was an site in the U.K., I believe. I had a great experience buying from the company I linked above and would recommend them. Good to know you are back on the road.

John B.

 

[SD_Montero]

Yep , the leak came from the hose on the right. Not the metal pipe. I went ahead and replaced both hoses while I was in there anyways with silicone hose from siliconhose.com Nice quality stuff by the way.

Hey I just had to find this thread again I got a drip in this same hose. These are new hoses though I got in from autozone(they don't fit quite perfect) . Anyways I'm wondering what size hoses you ordered and did you get their nice hose clamps and if you like them? Thanks much!

 

[MummifiedCircuitry]

If these are the crossover hoses on the back of the engine like the picture implies, I replaced mine about 6 months ago as well. I didn't need to pull the manifold or anything and local parts house didn't have them for Montero SR, so I just bought the ones for the Sport which were basically identical but 2" or so longer and cut off the excess.

 

[JohnnyBfromPeoria]

Anyways I'm wondering what size hoses you ordered and did you get their nice hose clamps and if you like them?

Did you read page 1? I responded about hose size and length and someone else suggested (wisely) to retain the stock clamps.

John B.

 

[SD_Montero]

Did you read page 1? I responded about hose size and length and someone else suggested (wisely) to retain the stock clamps.

John B.

I did read that I forgot you listed the sizes , thanks ...i lost the original clamps though, wishing I still had them now

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