HOT! transfer case. Normal? Magirus Deutz D17 allrad

[wilco]

I have a Magirus Deutz D17 allrad 4X4 X-Swiss fire truck.

It have a 256 HP V8 12 speed trans and a ZF65? Transfer case.

I have up graded the tires to 14.00r-20 tires from 12.00R- 20 tires

On a long drive today with several extended runs at 90+ KPH I started to smell gear lube.

When I looked underneath I could see that gear lube has come out of the transfer case vent and the case was VERY hot.

The fluid was a little over full so that may explain the overflow from the vent, but is this much heat in the transfer case normal?

I am going to drain the transfer case and refill with Amsoil severe gear 80W90 Synthetic.

If this is normal has anyone come up with a way to keep it cooler?

Was thinking about a fan and ducting and some bolt on cooling finned......

[egn]

You shouldn't overfill, as this may cause the effects you have seen.

If the oil was to hot, you should replace it with the correct amount. If possible, you should also install a temperature sensor with an instrument, to recognize problems early.

[Pirx]

Overfill of a transfer case will rise its temperature!

Pirx

[Filly]

What is "very hot"?
If you can touch it with your hand only for a few seconds before it really hurts then it is approx. 70°C. This temperature is quite normal for a gear box and wheel hubs with planetary gears.
Maybe you can measure the temperature with an infrared thermometer. If it has more than 80°C, then it is really too hot.

Christoph