Engine running hot (2001 Gen 3 Limited)

[Dartmouthbrian]

Hey folks.... Bought a Gen 3 a few months back. Low miles, granny owned. In heaven here.

I've been having the temp gauge issue since I bought it, however as of a few days ago I was driving the AC was working then it stopped working, then it started working again etc... And on and on.

So I went home, popped the hood and heard gurgling/bubbling noises coming the vicinity of the upper radiator hose/water outlet. I get the bubbling gurgling noise whether Im in stop and go or on the highway. This morning I drove it all over the place and kept the heat on the whole time. Got home and no bubbling/gurgling noises like I've been experiencing, which tells me keeping the heat on kept it cooler. The thing that boggles my mind is that is typically indicative of a radiator problem or thermostat, but it doesn't appear that either are the problem in this case.

Here are the things that I know

1. I replaced the thermostat & rad cap (did this shortly after I bought it)
2. No signs of a clogged radiator
3. No sounds from the heater core
4. No sounds coming from the water pump and water pump pulley
5. Upper rad hose gets hot pretty fast
6. Lower rad hose is also hot
7. I can look through the radiator it is externally clean.
8. Overflow tank is properly sealed (no cracks etc...)
9. No coolant in oil (so its not a head gasket issue)
10. The fan is working just fine


Im at a loss here... Any advice would be greatly appreciated. I've searched high and low on the internet for answers and can't find any.

 

[coffeegoat]

Could be a bad fan clutch - they can look like they're working but it doesn't lock up correctly.

Air in the system is another possibility, the standard fix is to park on an incline (engine up hill), open the radiator cap, and run it for 10-15 minutes adding coolant as necessary.

 

[01MontyLtd]

Sounds like air in the radiator if you can hear the liquid flowing. Try topping it off all the way until the reservoir tank flooded then drain the excess radiator fluid back to normal level. This process worked for me.

 

[122andy]

I'm in the process of replacing a bad fan clutch. Out of nowhere it started overheating when sitting still. I noticed that I no longer heard the "roar" of the fan on startup or at operating temp or overheating. As mentioned make sure its bled properly. This is the first vehicle I have ever had that uses bleed screws. Do you have an obdII tool to read actual coolant temp while driving?

 

[SirFrancisDrake]

I would also recommend getting an Ultra Gauge or Scan Gauge... something you can plug into the OBD port to get exact temps. Give you a little peace of mind. My coolant temps sit at 200-205 and don't go over 210-215 even when it's 110+ degrees outside here in PHX.

 

[Dartmouthbrian]

Hey folks thanks so much for the thoughts here. I meant to say in my original post that I bled the system, so to the best of knowledge its not air in there.

Clutch fan is not something I looked at before. I will take a look at that.

Also, I have Carista which is a bluetooth plug in OBDII tool, but unfortunately it doesn't give a temp reading grrrrr... Thanks for the reco's on the others.

Anyone else, if you have ideas or thoughts, please share them.

 

[Dartmouthbrian]

112Andy: Where are you from in Virginia? I am also from Virginia (Chesapeake/Va Beach), but live out in Seattle now.

I'm in the process of replacing a bad fan clutch. Out of nowhere it started overheating when sitting still. I noticed that I no longer heard the "roar" of the fan on startup or at operating temp or overheating. As mentioned make sure its bled properly. This is the first vehicle I have ever had that uses bleed screws. Do you have an obdII tool to read actual coolant temp while driving?

 

[Michael Brown]

Do you have coolant in the valley behind the water pump housing?

 

[Dartmouthbrian]

I meant to state in my original post that I do not have coolant there. One of the first things I checked. Thanks

Do you have coolant in the valley behind the water pump housing?

 

[haolepinoy]

Sorry to hijack, but quick question related to cooling system:

Does anyone know if the Gen3 have a brass/copper radiator like the previous generations of Monteros, or is it now aluminum from the factory? The one in my '03 is aluminum with a plastic top, and has "Toyo Radiator, Made in Japan" on the top left, but I don't have any way to know if it's the original (I'm the 27th owner, or something like that). Thanks.

 

[Dartmouthbrian]

Alright... So it appears that there may be some coolant in the valley. What's the diagnosis? Water pump? Im at wits end with this truck. It is starting to give me Land Rover flashbacks.. .EEEEEK!

 

[Monty85]

Sorry to hijack, but quick question related to cooling system:

Does anyone know if the Gen3 have a brass/copper radiator like the previous generations of Monteros, or is it now aluminum from the factory? The one in my '03 is aluminum with a plastic top, and has "Toyo Radiator, Made in Japan" on the top left, but I don't have any way to know if it's the original (I'm the 27th owner, or something like that). Thanks.

Mine came with Brass Top radiator. So I assume yours has been replaced

 

[Monty85]

Alright... So it appears that there may be some coolant in the valley. What's the diagnosis? Water pump? Im at wits end with this truck. It is starting to give me Land Rover flashbacks.. .EEEEEK!

Okay, sounds like you are in same battle as I was in.
I had issue with losing coolant every couple of weeks. When the coolant leven goes low enough, it would start overheating, specially while going long uphill.
Could not find the source for very long time and Valley was the start.
Waterpump and the Oring for the pipe that goes from Waterpump to the back of the engine was also replaced when I did timing belt job, but it FAILED!
So there was slow leak forming a puddle in the valley every now and then.
I did not want to take water pump out again, so I went from top revoming intake manifold to get access there. (it was good reason to do my valve cover and spark plus at the same time).
Just make sure to get Oring that fits nice and tight.

Hope this will fix your problem, but for me there was one more. Even after replacing the mentioned Oring, waterpump and such there was still a bubble that pops up in radiator.
I assumed I had bad headgasket, but one day I lost all my coolant all of sudden.
It was a broken plastic T-joint right under the car on passenger side, after the wheel area.
This is the line that circulates coolant to the rear heater core and that snapped !

After replacing that, I have not had any coolant loss or heating issue. It has been about a month, so I belive that did the job.

Good luck!

 

[Dartmouthbrian]

Hey! Thanks so much! I will check that O-Ring. I'll report back.

Okay, sounds like you are in same battle as I was in.
I had issue with losing coolant every couple of weeks. When the coolant leven goes low enough, it would start overheating, specially while going long uphill.
Could not find the source for very long time and Valley was the start.
Waterpump and the Oring for the pipe that goes from Waterpump to the back of the engine was also replaced when I did timing belt job, but it FAILED!
So there was slow leak forming a puddle in the valley every now and then.
I did not want to take water pump out again, so I went from top revoming intake manifold to get access there. (it was good reason to do my valve cover and spark plus at the same time).
Just make sure to get Oring that fits nice and tight.

Hope this will fix your problem, but for me there was one more. Even after replacing the mentioned Oring, waterpump and such there was still a bubble that pops up in radiator.
I assumed I had bad headgasket, but one day I lost all my coolant all of sudden.
It was a broken plastic T-joint right under the car on passenger side, after the wheel area.
This is the line that circulates coolant to the rear heater core and that snapped !

After replacing that, I have not had any coolant loss or heating issue. It has been about a month, so I belive that did the job.

Good luck!

 

[Michael Brown]

Alright... So it appears that there may be some coolant in the valley. What's the diagnosis? Water pump? Im at wits end with this truck. It is starting to give me Land Rover flashbacks.. .EEEEEK!

Try to determine if it is a slow leak or fast leak. Also you may be able to see a drip in the pool while running, but it is hard to tell without an inspection camera. If it is leaking from the o-ring that mine was, then you have about 4 hours of work.

This is how I repaired it:
Check lines to the overflow tank and clean out if necessary. Mine was clogged and would not pull extra coolant out of the tank. This plus a constant leak leads to low coolant and overheating.
Everything else below will require you to unscrew the tap valve in the radiator and drain all the coolant.
Next, you will have to get to the water pipes below the intake manifold. Disassembly is tedious, but the FSM has all the info.
2003 Gen 3 FMS pages 11B-6 to 11B-8 covers the upper plenum assembly and spark plugs (do not need to remove, but good time to change if you want).
Pages 11B-17 to 11B-20 covers the lower intake manifold and fuel injector rails.
This is also a good time to replace the intake gaskets.
You can order MAHLE https://www.amazon.com/MAHLE-Original-MS19533-Engine-Manifold/dp/B00H7RDKI8/ref=sr_1_11?ie=UTF8&qid=1501859687&sr=8-11&keywords=2005+montero+intake+gaskets
or DNJ http://www.ebay.com/itm/Engine-Intake-Manifold-Gasket-Set-DNJ-fits-03-06-Mitsubishi-Montero-3-8L-V6-/252960343074?fits=Year%3A2005%7CModel%3AMontero&epid=110037304&hash=item3ae59c8422:g:lO0AAOSw32lYntxh&vxp=mtr

Once all that is removed you should be looking at a pipe that runs from the back of the water pump housing to the rear of the engine. It is held on by bolts at the back of the engine. I took them off with a box end wrench and pulled it out of the back of the water pump. More water will leak out.
There is an o-ring labelled 13N on page 14-15 in the water pump diagram. This is the one that needs to be replaced. Over time, they wear and then leak.
The o-ring on the steel pipe is this one. https://www.amazon.com/gp/product/B008RJN2SS/ref=oh_aui_detailpage_o08_s00?ie=UTF8&psc=1
The larger pipe that runs over the passenger bank uses 2 of these. Mine was not leaking, but I already had ordered the wrong ones. http://www.ebay.com/itm/Genuine-Mitsubishi-Water-Pump-Tube-O-Ring-MD030764-/263070107538?fits=Make%3AMitsubishi&hash=item3d40334792:g:2isAAOSwLsBZWqH2&vxp=mtr

Reassemble following torque specs in FSM as possible. They are most important for the fuel rails and intake manifold. Follow the manifolds torque procedure to prevent leaks.

When refilling with coolant, make sure you loosen the 2 bleeder bolts in the assembly that goes to the thermostat housing.