The Mitsubishi Pajero Owners Club®

[SteveMilner]

Following on from this thread regarding problems with the cab heater: http://www.pocuk.com/forums/viewtopic.php?t=165087&postdays=0&postorder=asc&start=0

I have recently had issues with overheating. This only happens when I tow my caravan (about 1.7T) uphill for longer periods.

I've spent a month touring round Europe and this was when the problem became apparent. I toured 2 years ago on the similar long climbs in Europe (Central Massif, Pyrenees) without problem.

During long climbs the car heater gauge moves from normal and towards the right. At one point I had to pull over to prevent the gauge from going into the red. When that happens the reservoir bottle fills with fluid from the system. When the engine cools, this fluid is not returned back to the system (although I have potentially identified a hole in the pipe within the bottle which may be the cause of this).

Mitsubishi in Spain and have had a look at the vehicle and indicate that the flow through the radiator is fine.

I have a feeling the problem may be related to the viscous fan coupling. Even when the car was significantly towards the red on the temperature gauge I could easily move the fan by hand (it seemed to have exactly the same resistance when the car was cold).

However there are some other thoughts that I've been having.

The heater matrix works better when the car is at higher revs.
I can't tell if the heater matrix problem has been fixed, but in an attempt to to cool the car during the up-hill runs I was turning the heater to 29 and the fan to full and it certainly blew out hot air, but without the outside temperature being below 6 degrees it's difficult to be certain
When I stopped due to overheat risk the engine did not cool down down until I ran the engine in neutral at about 1500 rpm
The air conditioning does not get nice and cold unless the car is running at higher rpm (2000+)
I can not make the car overheat without the van attached.
Fuel consumption towing the van is normal for what I would expect and there is no evidence of the van brakes binding.
A pressure test of the coolant system shows no leaks.

My mechanic has checked the tension on the belt for the fan, and it seems to be fine. I'm assuming it's the same belt that operates the fan and the air conditioning compressor. Could something have been sipping, such as the pulley that drives the belt, but to be honest it seems unlikely.

Any thoughts gratefully received.

Regards,
Steve

[Google]

[MARKS600K1]

Hello  Steve

   I had this problem when I got my MK3 the final cure was a new radiator.  Although they pass water through some of the passages get blocked which reduces the thermal capacity of the radiator if they are blocked you can stand there all day flushing backwards or forwards won't make any difference. If you get some one to rev the engine while you watch the fan then switch off the fan should stop dead with the engine ! you should also be able to hear the fan roar at low revs.  If it is the viscus you can re-fill them there are threads on how to do it.

 Regards Mark

[Dmcmylor]

The back fill from the header tank to rad on cooling may be a problem with the valve in the rad cap sticking. Worth changing it for new with what they cost.

[assassin]

I always begin by cleaning the cooling system as you will be surprised how dirty they get, if you can get hold of a commercial or industrial cooling system cleaner then do so, and always follow the instructions to the letter as this is powerful stuff and can actually eat through metal if it is left in for too long, and I dropped some onto a car boot and it ate through the metal overnight.

Always drain the system by removing the bottom hose as any larger particles will not come out through the drain tap with its small bore and will remain in the system, and remove the lower rear heater rubber pipe to remove more water.

Flush your cooling system with water several times as the system has several voids and these trap water and cleaner in them, so do it more rather than less, I recommend flushing with plain water and draining three times and running the engine temperature between flushes.

[SteveMilner]

Well.

All eventually became clear.

I started getting overheating when not towing, and when I checked the radiator was leaking.

The rad had blown to such an extent that the sides of the rad were bowed out.

New rad, problem fixed and no more overheating either towing on otherwise.

Also, my lack of heating was resolved at the same time (See the link to the other thread in the first post of this thread)

Steve

[DI-Dick]

Thanks for the update Steve

Where did you get the new rad from?  Genuine or aftermarket?  Just wondering for info.

Couple of years ago I had to change the intercooler on my 2005 Shogun because it was so corroded and in areas had become paper thin.  New prices were horrendous and in the end I took a chance on a used one off Ebay which luckily turned out to be excellent.  Main radiator I would always go for new, but quality and fitting of aftermarket rads can be so variable.

[SteveMilner]

I'm not sure I remember.

I think my garage got it aftermarket.

Regards,
Steve

[SteveMilner]

Well.

The problem seems to have returned. Increase in temperature towing a 1.7t caravan up the hill on the M62 towards Saddleworth

I have read in other forums regarding a failing resistor in the gauge control unit as well as problems with EGT increasing connected to faulty injectors. These seemed to be older models though.

I've done 125K miles or thereabouts.

I guess it's back to the drawing board but I have within the last 12 months replaced a lot of stuff.

[SteveMilner]

My local garage is on hols at the moment and the car is behaving when not towing, despite crossing the Pennines twice daily, so I'll wait for them to get back.

Within the last 12 months I have replaced:
Radiator
Water Pump
Overflow bottle and pipes.
Thermostat
Rad cap (x2)
The car's coolant system has been flushed on more than one occasion.

Putting a list together of things to get checked when the guys get back:

If anyone wants to chip in any suggestions please do so.

1) Check coolant colour for contamination (less than 12 months old). If dirty flush and cleanse system, using commercial cleanser.
2) Check coolant levels, top up as required. Monitor for further loss.
3) Inspect coolant system for leaks and bubbles in overflow tank while running. (Cry if this is the case)
3a) Check thermostat replace if needed. (Thanks Craig SM)
4) Check all engine belts for correct tension.
5) Check viscous fan clutch for proper operation
6) Examine water pump for signs of wear/impellor damage/slip
7) Pressure test coolant system
8) Flush and cleanse oil system(service required anyway).
9) Check diesel injectors for correct function (not sure how to do this, would error codes be recorded)
10) Check EGT (is this possible?)
11) Change ATF/diff oils?

[Craig-SM]

Put a new thermostat in too. Normally fail in the open position but some don’t open.

[SteveMilner]

Thanks for that.

Forgot to mention that - Check Thermostat, although it is less than 12 months old.

Will edit the list.

[SteveMilner]

Updated List

1) Check coolant colour for contamination (less than 12 months old). If dirty flush and cleanse system, using commercial cleanser.
2) Check coolant levels, top up as required. Monitor for further loss.
3) Inspect coolant system for leaks and bubbles in overflow tank while running. (Cry if this is the case)
4) Inspect radiator & aircon- radiator for cleanliness & airflow blockages
5) Check thermostat replace if needed. (Thanks Craig SM)
6) Check all engine belts for correct tension.
7) Check hoses for integrity - vacuum collapse can cause impaired flow
8) Check viscous fan clutch for proper operation
9) Examine water pump for signs of wear/impellor damage/slip
10) Pressure test coolant system
11) Flush and cleanse oil system(service required anyway).
12) Check diesel injectors for correct function (not sure how to do this, would error codes be recorded)
13) Check EGT (is this possible?)
14) Change ATF/diff oils?

[SteveMilner]

1) Check coolant colour for contamination (less than 12 months old). If dirty flush and cleanse system, using commercial cleanser. All fine
2) Check coolant levels, top up as required. Monitor for further loss. System full.
3) Inspect coolant system for leaks and bubbles in overflow tank while running. (Cry if this is the case) No sign of bubbles. Chemical test for hydrocarbons negative
4) Inspect radiator & aircon- radiator for cleanliness & airflow blockages Visually all OK
5) Check thermostat replace if needed. (Thanks Craig SM) Tested and fine
6) Check all engine belts for correct tension.
7) Check hoses for integrity - vacuum collapse can cause impaired flow
8) Check viscous fan clutch for proper operation Tested and fine
9) Examine water pump for signs of wear/impellor damage/slip
10) Pressure test coolant system Tested and fine
11) Flush and cleanse oil system(service required anyway). Done
12) Check diesel injectors for correct function (not sure how to do this, would error codes be recorded)
             I have run a cleaner through the system
13) Check EGT (is this possible?)
14) Change ATF/diff oils? Done

I need to go towing to test again

[SteveMilner]

Problem has hopefully, finally, been resolved.

The last 3 things done -

Fitted additional ATF radiator
Replaced my main radiator (which was a non OEM) with an OEM Radiator
Refilled the viscous fan clutch with oil (hardly any left in it)

The car has just done 3K Miles round Europe up and down the Pyrenees and Massif Central without as much as a tiny rise in the water temperature above normal.

[kbike]

Hi Steve, the burning question is just how much silicone oil did you use to fill the fan clutch?