Transmission Temperature Question:

Regnillub

New member
I've noticed that my transmission temperature runs quite a bit higher (25 degrees) in 5th gear than it does in 4th gear (for the same driving conditions).

Any suggestions as to why this may be?

I'm wondering if the clutch pack for 5th gear is worn and slipping under load generating additional heat. The 4th gear clutch pack does not, so it runs cooler? I'm trying to figure out if the tranny needs some work.

(2005 Sprinter Chassis, 2006 Winnebago View, aftermarket tranny cooler, electronic tap into the tranny temp sensor.)
 

Nautamaran

2004 140” HRC 2500 (Crewed)
If something was slipping the TCM would notice and set a fault code.
At higher RPM the fluids circulate faster, so the ATF sump gets better cooling than at lower RPM...

-dave
 

calbiker

Well-known member
I would get a second opinion. 25 deg difference (at same rpm?) is huge. Measure the temperature sensor voltage that goes from tranny to TCM. You need to remove drivers seat to access cable going to TCM.

You could have a measurement error.
 

Midwestdrifter

Engineer In Residence
In 4th gear the trans is direct drive. There is zero motion between the K clutches, and only the brake clutches will have any relative movement. This may result in some temperature reduction.

Also, does your engine temp change when you change the gear? The trans fluid temp is coupled to the coolant temp. If you are seeing an engine temp reduction in 4th, you probably have a cooling system deficiency, or are running at nearly full throttle.

I have noticed that the TC clutch slip rate may be slightly different when you limit the top gear instead of using the drive "D" setting. I could be mistaken though.
 

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