Paj heat issue on a long hill

[Turgon]

Problem:- driving at a park in QLD on the weekend ( temp - 32ish). Got crossed up on a long dusty hill, pushing for a while to get it up ( high revs) and Paj started to heat up, temp went up to 2/3 - 3/4 and sounded like it had dropped a cylinder. it lost all power and then wouldn't idle. Got it down the hill and back to camp. Left in shade with bonnet up for two hours and all good again.

Cause:- ECU shutdown? vaporization issue? sensor overload?

solution:- extra fan? hood scoops? stop driving like a loon? Understand it is not a comp truck?

Anyone else have this one:-
Note:- Water pump and belt changed 12000 ago and no problems, car seems fine and mech looked and can't see any problems. He was the one with the loon comment.

[ferret]

I'd have to say I probably agree with the mechanic, big revs and low speeds will make most cars overheat pretty quickly. The loss of power and not wanting to idle would most likely have been caused by a sensor playing up or the ecu compensating for the thrashing and big temps that it was seeing by dropping a heap of fuel into the engine and retarding the timing.

[-Scott-]

I'm happy to accept that the dropped cylinder was caused by the overheating, but I don't accept the overheating is normal. In my experience, Mitsubishi cooling systems are excellent, certainly better than anything I've experienced from GM. In high 30s ambients, slogging at low speeds through soft sand, I've had underbonnet temps cause my battery controller to shut down - but the temperature gauge showed normal.

The most common fault is the fan hub - it doesn't "lock" when it get's hot, so the radiator doesn't get sufficient air flow at low speed.

You haven't mentioned your vehicle's model/age - is it time to recon your radiator?

Good luck,

Scott

[NJV6]

I agree Scott - I'd have the radiator out and get the top and bottom taken off it by a specialist and cleaned out. Cheap insurance and they will tell you how blocked it was.

The cooling system is very good on My 3.5. Long 1st low climbs (15mins) and the gauge never moved from half, I could smell the exhaust and everything getting hot and it made me wonder if the guage actually can go above half

[Reddo]

Yeah agreed, must be some issues with the cooling system. Our NJ never has had an issue with engine overheating even when towing hard. Auto box overheating - well that's another storey...

[Turgon]

Thanks boys, I will get the radiator checked. I had it flushed when we did the timing belt but will have a good look.

The mech didn't comment on that and thought he would know ( A friend who worked on Mits for 15 +years with the factory and is a big lover of Paj's)

Scott, the viscous fan coupling was replaced 6 months ago, so I hope its not that, they are quite expensive for the size.

I have never seen it do it before and couldn't make it do it again later.

Oh, sorry 93 V6 3L, 212000K. 2+ish spring/tb lift,30mm body lift ,Ball joint flip,31 simex CMT, Commodore injectors, exhaust upgrade.

Just your usual stock little PAj......

[J Top]

Also dirt, seeds, pollen trapped between the aircond rad and the rad, the rad needs removing regularly for an extrenal clean as well.
J Top

[hudson44]

Oh, sorry 93 V6 3L, 212000K. 2+ish spring/tb lift,30mm body lift ,Ball joint flip,31 simex CMT, Commodore injectors, exhaust upgrade.

Just your usual stock little PAj......

Did you find the commodore injectors made a difference? And which model are they out of? VN or ECOtech?

[Turgon]

Hudson,
They made a huge difference when towing ,It became very responsive. He did a fair but of tuning with it as well.

I think a ECOtec ( my Mech did it when I had the injectors out to clean them, said he would replace them, cheaper than sonic cleaning, I think it was an excuse) But I will check with him.

Thanks JTop, I will do.

[Locknut]

i have a NH auto and mine gets hot while in 4wd going up hills,and i have done it all new davis craig viscus hub,raidiator pulled out and cleanned,cooling system flushed and pressure tested,but still it keeps getting hot.
So i wired up the air con thermo fan with a switch in the cabin so when it gets hot i turn it on and it brings the temp down.
I have just put on a high flow muffler to see if the exhaust was blocked and causeing the temp prob but haven't been off road with it yet,all i know its a dead set pain in the arse seeing the gauge up near the 3/4 mark

[Overkill]

When we brought our NJ 3.5, I took the radiator out to do the body lift and took it down to the reconditioners for shits and giggles. Just to have it cleaned and tested. We were blown away with the amount of build up of grime in the core. The guy asked if it was overheating, due to the amount of grime in the finns, they were like a "smokers arteries". From looking inside the radiator you could see a small amount, but not enough to worry about. It wasn't till he added water that you could see how blocked it was, less than a litre to fill , I was amazed that it hadn't over heated or at least got real hot.

I would definately recommend getting the rad serviced, our guy recommended changing the fluid every 2nd oil change to keep the cooling system clean and working!

[-Scott-]

a switch in the cabin so when it gets hot i turn it on and it brings the temp down.

There's your answer. I'd say your Davies Craig hub needs to be returned. The A/C fan should not make that much difference to your engine temp if your engine driven fan is working properly.

Sufficient airflow will cool your engine, so the rest of your cooling system is working properly.

The A/C fan is there to supplement the airflow when your A/C is on and pumping hot air across your radiator. If you need your A/C fan when your A/C is not on, I'd say you still have a fault. And I've heard too many bad experiences with Davies-Craig products to assume their fan hub is flawless. Their electric fans may be OK, but I have doubts about the rest of their range.

My 2c,

Scott

[Reddo]

this is off the topic a bit, but a mate who has an NL Paj (2000 model) said they were all recalled to have the radiator replaced cause some were having overheating problems.

Just thought I'd chuck that in!

[Turgon]

Thanks Guys, A lot to do and so little time...... before the next drive.

Note to self remember to replace CV's as I now have a shot one on the left from the same weekend.


Has anyone tried to replace with an aftermarket radiator? but little room in there for a thicker core.

I did think of the switch for the thermo fan but thought " is it a bandaid solition for a bigger problem"

[-Scott-]

this is off the topic a bit, but a mate who has an NL Paj (2000 model) said they were all recalled to have the radiator replaced cause some were having overheating problems.

Just thought I'd chuck that in!

There have been some problems among Gen 3 Pajeros with overheating due to coolant gelling and blocking the radiator - I think it was something to do with incompatible coolants. I thought that was only affecting DiD era vehicles, but if it's a coolant issue it could be a problem in a Gen 2 - and it doesn't hurt to press a Mitsubishi Service Manager.

And while I'm on the subject, the Pajero Club Forum is reporting more and more instances of Mitsubishi Service Departments dismissing problems. This is a worrying trend, not good for any of us, so it's important to be prepared to fight them until you're happy your concerns have been properly addressed.

Good luck,

Scott

[Locknut]

so with the clutch fan is this how it supposed to work>>when its cold the clutch is tight and when its hot it is a lot looser ( if i can put in those terms)
when i turn off the car the fan only spins about id say a couple of turns and stops the old one would free spin for a while and slow down to a stop,
My thoughts of the clutch fan should be freeish when cold and nice and tight when hot..as you can tell no idea

[-Scott-]

My thoughts of the clutch fan should be freeish when cold and nice and tight when hot..as you can tell no idea

This is precisely how it should work - slip when cold, not when hot.

[Locknut]

well i have looked at a few clutch fans and they all seem to be the same slip when hot and tight when cold?
I know with my fan that when i run it from cold and hold the throttle open you hear the fan pulling the air across the motor and after a while you can really hear the noise diffence as the viscus coupling starts to slip.
This is what the gregorys manual says about it:
with the engins stopped,rotate the fan by hand a slight resistance should be felt.If no resistance or a very high resistance renew the coupling.
still have no idea of what the go is....but would be nice to find the answer as to me it all works the wrong way

[NJV6]

When it is cold it is tight and will like you say 'roar' on first start up for maybe a minute or so. Perfectly normal & every vehicle with a viscous fan I've come across is like this. *Edit - every vehicle with one that works properly.... *

If it is working properly you will hear the thing start up when things get hot. The fluid in the clutch gets thicker as it heats up, causing the fan to spin faster to catch up with the engine rotation. When the car is cold, the fluid in the clutch remains cold and the fan spins slowly.

It is hard to tell becuase of how they react when fully cold (tight) but when on your gauge it reaches say 3/4's it should engage. I don't recall my Pajero one coming on but the RR one when it did, you definately knew it (say climbing in low 2nd), sounded like an aeroplane taking off and the hot air would come rushing past the windows.

[Noisey]

Mine has been overheating aswell lately - so I decided to take the coupling to pieces and clean it out. Went to Toyota and picked up a tube of silicon oil, removed the fan assembly and took it to pieces. The "oil" inside had turned to glue and my guess is it was not doing its job.

I have not had any overheating issues since although I think that the 18ml of oil that Toyota supply may not be enough and maybe a second tube would be a good idea. For the price of $10 (per tube) it is a cheap fix and if it does not work then at least you know the problem lies elsewhere.