Engine Overheating

[nj swb]

Update...

Went to radiator specialist and had it removed and checked.
He found radiator to be at least 60% blocked and small crack in top.
I opted for new radiator and have given it a good test over the weekend.
Very happy with results, gauge did not move on climbs that previously went into limp mode.

That's a good result, thanks for posting the outcome.

Any theories for how / why the radiator was so badly blocked after 35,000 km? Understanding the source of your problem might help others avoid it.

[old Jack]

Update...

Went to radiator specialist and had it removed and checked.
He found radiator to be at least 60% blocked and small crack in top.
I opted for new radiator and have given it a good test over the weekend.
Very happy with results, gauge did not move on climbs that previously went into limp mode.

Good news Leon.
Did the radiator specialist give a reason why the radiator had reduced flow even though it was only 35,000k old?
Was it gelling through mixing coolants?

OJ.

[Leons pb]

Sorry I didn’t ask for a reason why it was blocked, just happy it’s fixed.
I have owned for last 25k and have noticed overheating the whole time when doing any soft sand or steep hill climbs.
Don’t know history other than it was set up for touring and towing.

After overheating on the beach and a few times on highway hills
I took it to Mitsubishi to get serviced and told them to check all the cooling system as I was concerned about it.
Service came back good no issues so was pretty happy as second owner.
They pressure checked the system for leaks and did a coolant flush for me.

Since the issue was still there I assumed I’d have to put up with it and adjust my driving style to suit as lots of others had similar issues.

So I upgraded intercooler, installed automate and engine data scanner to monitor temps and ease off if it started getting up too high.

Got sick of watching the gauge all the time so came here for advice because it just didn’t seem right to have to put up with it.

I guess before thinking the worst get the radiator removed and cleaned or replaced before spending on other things, not that I regret getting automate it really makes a big difference to drivability.

Thanks O.J and others for helping diagnose the problem

[old Jack]

I had been thinking it was a coolant flow problem but since the radiator was near new and had had a MM dealer flush and check the next step was to suggest changing the water pump. I do not know of an accurate way to check the flow rate of the cooling system in situ, does anyone know if this is possible?

OJ.

[Steve76]

I had the issue of coolant getting pumped out the overflow bottle after towing my camper for about 2 hours in my 2012 pb . It didn't overheat , I stopped in time . I let in cool down and refilled radiator and was fine after that . I booked it in at the local Mitsubishi dealer for a stress test . Which it failed . A goodwill claim was put in to Mitsubishi. 2 weeks later I got a call saying they would replace the engine , new long motor . Was great service , the original motor had done 205k . Never been serviced at a Mitsubishi dealer . Very happy with that outcome .

[old Jack]

I had the issue of coolant getting pumped out the overflow bottle after towing my camper for about 2 hours in my 2012 pb . It didn't overheat , I stopped in time . I let in cool down and refilled radiator and was fine after that . I booked it in at the local Mitsubishi dealer for a stress test . Which it failed . A goodwill claim was put in to Mitsubishi. 2 weeks later I got a call saying they would replace the engine , new long motor . Was great service , the original motor had done 205k . Never been serviced at a Mitsubishi dealer . Very happy with that outcome .

Thanks for sharing. Great outcome, great customer service from MMAL

OJ.

[acem8]

An update on my overheating issue that began in November last year. I agreed to pay the 'diagnosis fee' at the dealer but ended up paying nothing because it failed and a new motor was ordered under warranty. It went in for the fix mid-January and 3 courtesy cars later I got it back mid-June. They couldn't get it started and run smoothly and it was eventually traced to a faulty plug on the wiring loom so they managed to source a second-hand one.



The timing belt was due on the 90k service so that was done for free and all the failed starts hadn't done the battery much good so I got one of those as well. So you would think it was a reasonable result but it still isn't running anything like the previous one. There is a secondary noise coming from the passenger side of the engine bay, most noticeable then idling and when the engine is up to temperature. It is not linked to the engine rpm, it seems worse when there is no load on the engine but maybe I just can't hear it when it is being revved. I've been through 3 fresh tanks of fuel and an additive but it is getting worse rather than better. Also fuel economy is 15-20% worse compared to the old engine - even when it was brand new.


It is going back in tomorrow, does anyone have any idea what may be the issue? My only guess is the injectors need to be adjusted or calibrated.

[picard]

Hi guys on the subject of overheating, Iv had an ongoing issue with it and running out of options.

2010 pb 146,000km, bullbar, winch, spotlights,bash plates up front.
Platform roof rack, dual battery’s, LT265/70/17 AT tires, LRA 135L long range tank.
Don’t think it could handle towing is current state but has towed previously.

Iv had coolant flush and pressure check by Mitsubishi, 127kpa cap on since I’ve owned it 20,000km I’m 2nd owner so not eligible for 10yr drivetrain warrenty

Never looses coolant just odd few splashes to show it got up a bit from overflow and radiator cap.

I have a scangauge which I watch religiously and back off if gets too hot.
2 times I have hit the warning CEL light on at approx 115°

Temp keeps rising if on steady incline even on a fairly flat highway.
It actually heats up quicker at high speeds than short sharp hills.

Temp drops just as quick once I ease off throttle so seems like radiator can’t keep up with demand while loads on.

On slight hills it is common for temp to rise up to 95-105 with extended or steeper stuff continuing to raise it.
On short hills in hinterlands I can control the temp well with sport mode and automate keeping gears low and revs high.

I have installed forefront intercooler and piping, new coolant temp sensor, AUTOMATE
And still overheating.

I feel like new radiator thermostat and condenser is final chance to fix it before something worse happens, love the car but don’t want to be constantly be worrying about the temp rising.

What’s your thoughts OJ?

Hi Guys,
just posting that ive just had the same situation today ,as above, whilst towing a 1200kg camper. 113000 ks. on clock.

On long ascents my EDS recorded temps of up 108 degrees (although the needle never went to the red zone it crept close.
Checked coolant checked when temp was 105, no bubbling but coolant splash noted.
history of car is cooling campaign done 85000.
New radiator as original was blocked although the radiator cap would be the lower kpa type.
My question is could it be a combination of ironman bullbar with winch larger tyres and a lower kpa radiator cap.

Also after hour thirty drive had to top up radiator with approx 350 to 450 mil of fluid


Any info would be appreciated, cheers

[old Jack]

Hi Guys,
just posting that ive just had the same situation today ,as above, whilst towing a 1200kg camper. 113000 ks. on clock.

On long ascents my EDS recorded temps of up 108 degrees (although the needle never went to the red zone it crept close.
Checked coolant checked when temp was 105, no bubbling but coolant splash noted.
history of car is cooling campaign done 85000.
New radiator as original was blocked although the radiator cap would be the lower kpa type.
My question is could it be a combination of ironman bullbar with winch larger tyres and a lower kpa radiator cap.

Also after hour thirty drive had to top up radiator with approx 350 to 450 mil of fluid


Any info would be appreciated, cheers

Auto trans or manual?
If Auto do you have a TC lockup fitted, if so what type?
If Auto are you using sport mode or just "D"?

Split pan design bullbar, winch and larger tyres will all be adding to the stress the cooling system is under as will insect screen, driving lights and aftermarket under body guards. That said 1200kg is not a huge load and I have towed just under the 2000kg mark, in hot 36C + heat up sustained very steep hills whilst testing Lockup Mate and Auto Mate and I have not seen engine coolant temperatures that high.

I would expect to see coolant flowing into the overflow bottle but it returning to the radiator overnight when the engine cools down. Is this happening?

Is there any chance the coolant could have been mixed at some stage? Some coolants gel when mixed with other coolants and this greatly restricts the coolant flow through the radiator.

OJ.

[Scooby]

In regards to water pump coolant flow testing.
On earthmoving machines I used too measure the water pump outlet pressure.
Not sure if the Pajero has fittings that you can get into.
Generally looking for about only 5 to 10 psi. Hi revs. (Radiator cap off)
Not an exact science and may have to measure a few to get a base line.
But too high means a blockage or too low pump problem. ( depending on engine configuration.)

[picard]

Auto trans or manual?
If Auto do you have a TC lockup fitted, if so what type?
If Auto are you using sport mode or just "D"?

Split pan design bullbar, winch and larger tyres will all be adding to the stress the cooling system is under as will insect screen, driving lights and aftermarket under body guards. That said 1200kg is not a huge load and I have towed just under the 2000kg mark, in hot 36C + heat up sustained very steep hills whilst testing Lockup Mate and Auto Mate and I have not seen engine coolant temperatures that high.

I would expect to see coolant flowing into the overflow bottle but it returning to the radiator overnight when the engine cools down. Is this happening?

Is there any chance the coolant could have been mixed at some stage? Some coolants gel when mixed with other coolants and this greatly restricts the coolant flow through the radiator.

OJ.

Hi OJ,
Its Auto with no TC fitted was using sport mode for most of trip always on gradients
.
A few hours of cooling i noted that the coolant bottle was empty, crack the radiator cap, no pressure noted, top up both radiator and overflow to with approx 450 ml of water.


The after market radiator was installed by Natrad can only assume that it was completely flushed of old fluid. although they used there cap of lessor kpa.


I am thinking that part of the issue is at least the winch which blocks up a significant amount of air flow...
thanks Picard

[old Jack]

Hi Picard,

I would be checking the easy and cheap things first before drastic measures about bullbars and winch removal. Up until the Natrad visiting were things ok?

If you have a genuine radiator I would be fitting a new genuine cap, either the high or low pressure it does not matter.
I would be replacing the hose that runs between the radiator neck and the overflow bottle. This hose must have a 100% seal to both the radiator overflow outlet and the overflow bottle, these hoses age and lose tension and are not vacuum tight, in some cases they can collapse on the inside so when the cap opens to allow the coolant to be sucked back into the cooling radiator the hose collapses and restricts coolant flow.

Park the car with the nose up or put the front wheels on car ramps, remove the radiator cap (when cool enough to safely do so) and then run the engine until coolant temperature is up and the thermostat is open and you can see coolant moving through the radiator. Run for a further 5 minutes then turn engine off and refit radiator cap and ensure there is coolant in the overflow bottle up to the mid to high level. When the engine has cooled down to ambient you should see the coolant level in the overflow bottle drop and when checking the radiator level it should be full. This procedure will ensure there are no airlocks in the cooling system.

Then keep a daily diary of the cold coolant level in both the overflow bottle and in the radiator. Once you a have a weeks of observations then we can look at these.

OJ.

[spot01]

I'd also check the engine oil for correct level &/or any sign of contamination by coolant, eg, milky residue inside filler cap.

[Challenged1]

Also check the condition of the radiator hoses, top and bottom. They should be reasonably firm at ambient temperature and a little spongy at running temperature. Observe both hoses while increasing RPM and make sure they are not being "sucked" smaller. If they are too soft, they will collapse under increased coolant flow and eventually restrict the flow.

You can also observe the condition of the coolant. DO NOT REMOVE THE RADIATOR CAP when the engine is at running temperature. Serious burns can occur! With the engine cool, start the car with the radiator cap off. Is there any brownish residue "floating:" with the coolant? Stick a piece of tissue
paper (holding onto it of course) in the coolant and observe the colour when you remove it. Is it coolant colour only or is there another colour with it?

If there is any colour on the tissue paper other than that of the coolant, there is a leak into the cooling system somewhere. Most likely an internal leaking head gasket.

Any exhaust gasses or oil leaking into the coolant will "stain" the coolant.

This is a test that was given to me by an elderly mechanic many years ago now when I was having problems with a Ford V8 in an early L300 Mitsi van. Sure enough, the tissue had brown spots on it that indicated exhaust gasses leaking into the cooling system.

If there is no other colour, let the engine warm up so the thermostat opens (you will see the coolant flowing through the radiator) and do the same tissue test. Still no other colour than that of coolant, then refer to previous suggestions.