Transmission Oil Coolers

[nj swb]

When towing, what would be considered as an ATF temp that is approaching too high?

100 degrees is only significant because it's the boiling point of water - by definition.

Modern coolants boil significantly above 100 degrees, and oils can cope with higher temperatures again.

But 100 degrees is a nice round number to remember, so I start to pay close attention once temps exceed that. At 120 degrees I would be finding some way to pull over and let things cool down - if pulling over isn't an option, change down a gear or two, and go a little slower until you can pull over and/or temps drop back below 100.

By the time a warning lamp comes on (somewhere above 140, I believe) the oil is cooked, and needs to be replaced. The life of your transmission has probably also been compromised.

[Gwoolie]

Has any one fitted one of these?

Mitsubishi Pajero Sport QE 2015 - 2019 iDrive WindBooster Throttle Controller

Supposed to be better for towing and off road ??

[old Jack]

Has any one fitted one of these?

Mitsubishi Pajero Sport QE 2015 - 2019 iDrive WindBooster Throttle Controller

Supposed to be better for towing and off road ??

You do not get any extra power or torque from a throttle controller, all you do is decrease the response time of the electronic throttle.

OJ.

[BillS]

Before jumping to conclusion I would be checking the accuracy of the Scangauge, first thing in the morning before the engine is started, all the temperatures should be the same as ambient.

Also are you driving the PS in in Drive?
The factory AT programs tend to change up gears too early, by using a gear lower and holding a few more revs the load will be taken off the engine and the torque convertor in the transmission will remain locked up. This should reduce all the engine and transmission temperatures.

I suspect the "water boiling" sound was just the coolant going into the overflow bottle which is normal.

OJ.

On the long climbs I use manual mode, coming from a BT50 where I pretty much drove it in M all the time when towing, had to fit a cooler to it as well which worked well, oil temp where usually lower than water once cooler was fitted. I think you a right about the water sound, I lifted the bonnet and sound seemed to be in the overflow bottle it also stopped as soon as I started the engine again. Coming home yesterday I was watching the taco on climbs and there seemed to be
a bit of slip in third and fourth was locked from what I could tell.

I do like the transmission, as nj swb stated it dose tend use a higher ratio which is the opposite to the BT50 and the paddles are great for manual shifting.

I have the Boo's sump plates fitted, may cut cut a few slots in these to allow more air to escape from underneath. Have an ECB alloy bull bar fitted but this has more cooling holes than any others I looked at so I can't do anything there.

[old Jack]

The BT50 /Ranger has a very poor ATF cooling system from the factory and these are prone to high ATF temperarptes and transmission failures. The Pajeo Sport has a much better ATF cooling system from the factory, it has an in radiator ATF cooler and a separate ATF cooler fitted as standard.

The ECB bar has a lot of airflow openings so I would avoid cutting more holes in it.

Not sure about Boo's plates but I found on my Challenger fitted with Bushskinz plates, and both the Pajero Sport and Challenger front ends are very similar, that I was losing airflow through the sides of the front plate and through the slots!

My solution was to fit some rubber side baffles to the plate do air could not escape out the sides and to also cover up all the slots in the plate. My engine air inlet, engine coolant and ATF temperatures all decreased significantly. If you still habpve the factory front plarpte, try refitting it and see what happens. What you want to do is force all the air that enters through the front grille and vents to be forced through all the heat exchangers. Air will take the path of least resistance and escape out the sides of a flat guard rather than go through a heat exchanger. I also believe the slots in the plate combined with the plate angle can either suck the air out or disturb the airflow so it decreases cooling.

How are you knowing when the torque convertor is unlocked?

Have you checked the calibration of your Scangauge II?

OJ.

[Jasonmc73]

I thought tranny oil temps over 120ish degree was a problem?

Most service schedules do suggest shortening up the diffs & tranny changes along with engines in these condittions.

As a young fella grew up in Landcruiser utes & father was trucky, manual tranny's & standard practice pulling loads up hills was to drive to the conditions & stay within the vehicles limitations or they would get too hot.

A practice I still practice, lower gears higher revs will give cooler results.
I'm not talking redline revs either

Same principle for tractor pulling a plough be it manual or powershift trannny, or a tractor running the PTO in 540RPM, stick it in higher gear 750 PTO & lower the revs which we call economy PTO you still get 540rpm out the pto at lower revs, but the machine will get hot, tranny & engine & burn a stack of fuel.
Same as driving a vehicle up hills in a higher gear pulling its own weight/ load, I actually use that as an analogy to try & teach people the correct procedure for lowering fuel use & engine heat in tractors under load, machine or vehicle will get hot.

Just an opinion

[DibbyDibbyDJ]

Have an ECB alloy bull bar fitted but this has more cooling holes than any others I looked at so I can't do anything there.

Did they refit the factory air deflectors after fitting bar? Not having these fitted can lose you a few important degrees

[BillS]

Just checked the cold temps and seems you are onto something here Jack the out side temp was 24 water 26 trans 36! so it is out by 10 degrees. OK just checked my setup for the trans temp and I had the numbers for the wrong model, change to PS settings and temp went down by 10 degrees so a big jump already thanks for the heads up on that one Jack sounds like like you have struck this before. Anyway this makes a big difference and now a lot happier.

I will have a look at the baffling up front, I left the baffle of from the bottom of the radiator as I didn't have time to cut and refit it but that will be done first also the car came with a nudge bar and 2 plastic baffles on either side of the radiator had been cut down so will look at these also.

Going to Tassi in 3 weeks so want all the bugs out by then.

[BillS]

Car deferentially wasn't lugging on the hills am well aware of this.

Jack re torque converter slip I was just watching the taco it would move around a bit, this didn't seem to have once in fourth this was using sport mode which I tend to do on bigger hills.

[Jasonmc73]

Once you are sure your instrumenst are working correctly & your obtaining the correct data, try lower gears from the onset of load/ large hill just for comparison, see what the result is obove the normal operating temps?
Infrared heat guns are ot expensive if your worried, I use them a fair bit at work.
Not after the tranny has got overly hot as it won't cool overly fast & then you'll know if lowering the load on the drivetrain through mechanical advantage has any results on operating temps & fuel burns for your application for the particular machine.

[old Jack]

Hi Bill,

Certainly refit the bottom plastic baffle/air dam between the base of thr radiator and the bash plate. Depending on the bash plate you may need to trim the baffle so it does not touch the bash plate, it is important to have a small amount of clearance (3mm) between the plastic baffle and the plate because the bash plate attaches to the chassis and the baffle attaches to the radiator which is attached to the body. The body and the chassis move independently.

I have just had a look at the Boo's plates online and I can see they are a similar flat design like Bushskinz plates. This design allows incoming ram air from the front to easily exit the side of the plate rather than force to air through the bottom of the radiator and intercooler. Closing these open areas in with a flexible rubber baffle stops the ram air from escaping sideways, I would also be tempted to trial covering over the slots in the plate.

Here is the write up on the Challenger Bushskinz mod.

https://www2.pajeroclub.com.au/forum/showthread.php?t=50101

OJ.

[old Jack]

Car deferentially wasn't lugging on the hills am well aware of this.

Jack re torque converter slip I was just watching the taco it would move around a bit, this didn't seem to have once in fourth this was using sport mode which I tend to do on bigger hills.

Hi Bill,

Below is a speed vs rpm guide for the Pajero Sport for a given gear.
If the rpm is higher than that listed then your TC is slipping and generating a lot of heat quickly so it is time to change down a gear.

4th gear with TC locked.
90kph 3265rpm.
85kph 3084rpm.
80kph 2902rpm.
75kph 2721rpm.
70kph 2540rpm.
65kph 2358rpm.
60kph 2177rpm
55kph 1995rpm.
50kph 1814tpm.

3rd gear with TC locked.
70kph 3370rpm.
65kph 3130rpm.
60kph 2825rpm.
55kph 2589rpm.
50kph 2354rpm.
45kph 2119rpm.
40kph 1883tpm.

Torque convertor does not lock in 1st or 2nd gear so if climbing a very steep long hill with a heavy load, using these gears, you need to watch the ATF temperatures really carefully. The Pajero Sport has a 1.94:1 high slip torque convertor so it will slip for quite sometime before you get the torque convertor to stall, ATF temperatures climb very quickly when the TC is slipping.

I have not checked the Pajero Sport, but the 5 speed Jatco and Aisin autos in the Triton, Challenger, Gen 3 & 4 Pajero all unlock the torque convertor once you are coasting, this is to save fuel. However if you have just finished a long steep climb and the ATF has got hot then it will not cool down on the downhill run because the TC is unlocked so the ATF is not circulating through the ATF coolers.

We discovered this when working on Lockup and Auto Mate TC lockup kits, so Marshall from MM4x4 has programmed Lockup Mate to keep the TC locked up when going downhill. Auto Mate is programmed to unlock the TC when going downhill unless the ATF is 85C or above, if thenATF is 85+C then the TC is locked so ATF cooling can occur.

OJ.

[BillS]

Thanks for the info Jack. Fitting the bottom baffle doesn't leave much of it left so I might fit a rubber strip to the baffle as well to seal it against the sump plate, I saw the big gaps on either side at the front of the plate as well, thinking of closing that off with a plate on either side.

The slots cut in the front of Boo's sump plate start just below the radiator so with bit of rubber on the baffle they will be pulling air from behind the radiator with a bit of luck. There are 2 angled flats on the middle sump guard might cut a couple o slots there, might help with a bit more air flow.

I tend to drive it between 2000 to 3000 rpm on the steeper hills, below 2000 and it dies pretty quick if it's working.

[BillS]

Went for a drive yesterday and the oil temp was indication a much better number the highest it got to was 85 which is very good on a 24 degree day, this was without the van at freeway speed. Helps to have the scan gauge programmed right!

[old Jack]

Went for a drive yesterday and the oil temp was indication a much better number the highest it got to was 85 which is very good on a 24 degree day, this was without the van at freeway speed. Helps to have the scan gauge programmed right!

Hi Bill,

Not sure when and for how long you had 85C but typically on a mid 20C day at 110kph on undulating roads, TC locked in 5th in my Challenger I would see 65C to 70C ATF temperatures. I still think it is worth your time to experiment with covering the front bash plate vents and installing side gussets to prevent ram air from escaping. If you also monitor your engine air inlet temperatures this will give yo a good idea of how well the intercooler is working.

OJ.