Auto trans heating when towing

[CptClinac]

Hi all,
I have an elderly Safari which I use for towing my weighty boat. The auto has a trans cooler fitted.
The system gets hot when towing uphill.
I imagine the heating is basically energy loss in the torque converter. Thinking on from there, a TC lockup switch could reduce that significantly.
I have read that factory TC lockup can happen in several gears. Which ones? In all models??
What issues could I expect with TC lockup in lower gears??

Also, what differences in the internals of the engine between turbo & non turbo diesel? (piston cooling oil jets etc.)

Also, is it the same auto trans unit for turbo & non turbo? (Beefier innards?? Different computer/settings?)

Thanks
Dave

[jff45]

I note the term "elderly" so wonder what sort of mileage you have on the auto trans. Age can also be a factor in heat being generated through general clutch slippage.
I'd also like to ask you how you know it's getting hot. You don't mention any specific temperature so I'm wondering if you have a temp gauge.
If it's the trans temp light you're seeing in the dash then you're already in trouble because that comes on at 140C and means trans fluid is well cooked.
Factory trans coolers are generally insufficient for heavy towing.

I would imagine it's the same trans for diesel versions, turbo or not. They are quite strong but, like us, have a limited life..
Do you know the service history of this trans?

[Chubba]

G'day Dave
I have a '98 GU 4.5l petrol auto and it locks up in 2nd, 3rd and OD when the TCU senses all the parameters have been met for a lock up. OD at highway speed I find that it will lock up easily enough but will also easily unlock. On some steep hills on the highway I will put it into 2nd and sit on 80kmh and the lock up comes in and will tend to stay locked. Both situations are in a fully loaded car. The OD at highway speeds I find the trans temp rises the most and I would drop it back to 3rd to allow it to cool down for a bit. I have since installed a manual lock up for this reason and find it works great at temp control.

[CptClinac]

Thanks guys,
No temp gauge, using engine (radiator) temp and assuming that one effects the other. Also there's a hot trans oil smell. Never had the warning light lit.
No idea of heritage of machine. I think it was parked up at a farm and disused for some time. 300,000 on clock. Apart from a clean and check I had done a little while back, service history also unknown.
I've never had unit lockup apart from in top gear at open road speed. Mind you, it may be doing it and I think it's just another gear change.
PS elderly = 1988
Greypower rulz

Dave

[Chubba]

Oh. So engine temp rising, that's another matter. 1988, might be time for new radiator.
I had a heating problem when I first got my GU. I went full hog and replaced radiator,AC condenser,thermo fan and upgraded trans oil cooler. No more heating problems.

[jff45]

Dave, it might be an idea to drop the pan to see what you find then wash the gauze strainer and put new fluid in.

A temp gauge on the trans is a must, IMO, if you're towing heavy. Also a big trans cooler.

[Chubba]

Yeah 100% agree.

[tuckertrucker]

Hey Dave, I have a '92 Safari and use it for towing heavy loads too. I've noted that the floor around the trans and the centre console can get warm (not hot) when towing heavy loads for extended periods up a hill. Had a local diesel tech check out my trans oil cooler which turned out fine, and he said I just have to keep an eye on it. Agree with jff45 on transmission temp guage as the thermometer under the hood gets its temp from the engine cooling fluid (in mine any way) so wont get a temp form the tranny. He did say though that the auto transmissions used in my era of safari do tend to heat up quite a bit when under load, especially when in overdrive.
My auto trans will go into lockup in 2,3 and overdrive when its warm. You can feel it and hear it in 2nd and 4th, but never really noticed it in 3rd. But in my experience it wont lockup if the overdrive button is off. I'm not sure of the '88 transmission, but the auto in mine (factory) is a 4speed, with the 4th being overdrive.
Hope this helps,
Dylan.

[CptClinac]

Thanks TuckerTrucker,
I went down to the bloke who did the last trans service to check on when next service due. Also picked his 'expert' brain.
He flushed with synthetic fluid which can stand a higher temp 180+ rather than 130+. This puts the danger temp well past the over temp light turn on.

Also talked about TC lockup. It appears in the early versions (mine) the clutch in the TC is not very significant, and therefore should not be locked up unless engine is lightly loaded. Hence my machine locks up only in top.
Temp gauge is underway - thanks JFF & Chubba

Dave

[FNQGU]

I also find that the full synthetic fluid does not get to the temps that standard ATF fluid gets to either. That said, I would not like to see my tranny temps get anywhere near 180C, or even 130C for that matter. Even when towing the boat my temps rarely get into the 90's now, and at highway are in the high 70's - low 80's.

You'll know whether you have an issue once you get your temp gauge in.