77 m880 trans cooling question

[Weezer4117]

Just picked up a 77 m880 with a western plow. I noticed that the transmission cooling lines were cut and one hose connects each port that should run to the radiator. There are two nipples that are on the transmission that go to the radiator, does it matter wich nipple they connect to on the radiator? On the transmission there is one nipple towards the front and one towards the back, wich one does the fluid leave the transmission and wich one accepts the cooled fluid in?

 

[m880 unimog]

i know it matters which way they go round,it was around 20 years ago i found that out the hard way-all i did was to swap them around and it,s been good to go since.

i just looked in my hahaynes manual=nothing

 

[Weezer4117]

Im pretty sure the nipple in the front is where the fluid leaves the transmission and the one towards the back is where it enters after being cooled. Can anyone varify this? I dont want to learn the hard way!!!!!

 

[Elwenil]

The tube toward the front of the 727 is the pressure tube. From the factory it should go to the passenger side of the radiator. The fluid returns from the driver side of the radiator and goes back int eh transmission from the rearmost port.

 

[Weezer4117]

Elwenil- Thanks for your reply, saves me a headache and possibly a transmission!!

 

[Weezer4117]

I have hooked all of the cooling lines up as mentioned. The transmission and floorboard of the cab still are getting hot. Im at a loss as im sure this isnt normal. Would low levels of ATF cause this?

 

[Bob H]

Make sure to check the level with it in neutral, not park.

 

[Weezer4117]

Make sure to check the level with it in neutral, not park.

I can never get the same level on the dipstick. I have even kicked around with putting a external cooler on the trans, since i push snow with it and all. I dont drive it alot in the summer, maybe 200 miles to haul firewood.

 

[Bob H]

I can never get the same level on the dipstick. I have even kicked around with putting a external cooler on the trans, since i push snow with it and all. I dont drive it alot in the summer, maybe 200 miles to haul firewood.

The 1st step should be to address the inconsistent dip stick readings.
Verify that you are not the cause of the variances, then on to what else could be causing this.
Vehicle parked level.
Transmission at normal operating temperature.
Transmission in neutral (wheels chocked/parking brake set)
remove dipstick and clean it off
insert the dip stick fully, the cap will fit over the tube.
wait a second then remove the stick and get your reading.
If you are noticing that the fluid mark is higher on one side of the stick than the other, I have found that the bottom side of the dip stick picks up fluid from the tube and will read higher than it is.

Now after controlling the above level check and it is still inconsistent, I would recommend a fluid and filter change.
Normal trans oil temp is usually around 200°F.

If you do put a cooler on it, you still want it to run through the radiator, especially in the winter.

 

[Weezer4117]

What drives the fluid from the trans to the radiator? Is there a specific pump for this? Please excuse my ignorance....

 

[Weezer4117]

Anyone??

 

[Bob H]

Only one pump in the trans, which is turned by the torque convertor and creates the pressure for operation.
again a trans should run 200°F under normal conditions, 250°F if your working it. 300°F is too hot.

 

[abh3]

Make sure the rod from the carb to the pressure valve on the tranny is hooked up and adjusted properly, that'll make 'em run hot...

 

[Weezer4117]

Valve on the carb to the tranny?? I just rebuilt the carb and I dont recall anything going to the trans. Could be my problem then, ill have to find a diagram somehow... Thanks

 

[N1265]

Also, I would Check the oil level in the transfer case .