Thread: Zf auto cooling

Im wondering if the radiator tank heats the oil from transmission up to temp quickly then the purpose of the front mounted cooler is to help when temp spikes may occur .

YES. Too cool fluid is as bad as too hot so it is regulated around 88C .
I have never had my overtemp light come on except once when the sensor got wet and that includes towing 1ton in 45C.
Regards Philip A

Originally Posted by PhilipA

YES. Too cool fluid is as bad as too hot so it is regulated around 88C .
I have never had my overtemp light come on except once when the sensor got wet and that includes towing 1ton in 45C.
Regards Philip A

First time I have ever heard this. I did a search and here is a quote from a trans specialist.

Tests have shown that the typical original equipment oil cooler is marginal at best. ATF that enters the radiator cooler at 150 degrees C. leaves at 115 to 135 degrees C., which is only a 10 to 20% drop in temperature, and is nowhere near good enough for extended fluid life.

Their website.

General Information - The Transmission Centre

I think I believe land rover before a trans specialist. I also think they have mixed up f and c.

My D2 does not run cooling through the radiator so how does it heat the oil?

What about some cars(Falcons come to mind) that have known failures of the radiator transmission cooling so it is recommended that it be bypassed and a separate air cooler be fitted?

I have seen it written that most auto transmission failures are related to high oil temps or oil overheats .
Aftermarket tow packs fitted to many vehicles include additional oil cooling capacity .

Sent from my GT-I9305 using AULRO mobile app

My D2 does not run cooling through the radiator so how does it heat the oil?

It doesn't but a D2 TD5 has a 2800RPM stall speed which will heat the oil pretty quickly.
The D2 TD5 cooler is also enormous vs a RRC cooler so you can assume that cool oil is not a real problem in D2 TD5.
The D2 also has electronic control of the lockup which ensures it does not lock if too cool, and unlock will always heat the oil.

One reason I use full synthetic as its obvious that the D2 TD5 trans runs hot and Transmax z is much more stable at over 100C than Dex2 or 3.

Regards Philip A

Originally Posted by PhilipA

It doesn't but a D2 TD5 has a 2800RPM stall speed which will heat the oil pretty quickly.
The D2 TD5 cooler is also enormous vs a RRC cooler so you can assume that cool oil is not a real problem in D2 TD5.
The D2 also has electronic control of the lockup which ensures it does not lock if too cool, and unlock will always heat the oil.

One reason I use full synthetic as its obvious that the D2 TD5 trans runs hot and Transmax z is much more stable at over 100C than Dex2 or 3.

Regards Philip A

Its a pretty standard part from LandRover. I understood the same cooler is used in the D2 V8 and the P38 4.0 and 4.6V8. Despite its size, I think it is marginal still and I run an additional inline ATF cooler which now does a really good job.

My 300TDi does not run Auto Trans. oil through a cooler in the radiator tank and I haven/t noticed any other TDi 300 that does.
I have a later model oil cooler on mine, twice the size of the original 94 Disco, If I had a choice and I had trans oil cooling in the radiator, I would fit an aftermarket or larger later model disco cooler.
But I would tap into the rad. cooler outlet pipe and connect it through the air cooled aftermarket/later Disco cooler and then back to the box.
With just an air cooled cooler up front when idling or driving real slow in traffic or on a rough track, there is NOT enough air to cool the oil in the oil cooler.
So IF you have a radiator cooled trans oil cooler, plumb it as above and you will get cooler trans oil at crawling speed and sitting in traffic, or fit some fans to your air cooled cooler, Regards Frank..