Viscous Coupling Longevity

[buster]

Is there an average life expectancy for the more traditional, VC based AWD systems, such as the one used by Subaru? Occasionally you read of torque binding issues during the high mileage life cycle of cars that have VC's. I've even read that higher mileage VC based AWD systems lose their ability to transfer power back and forth as they age.

The fluid does shear over time. Air can also create problems.

 

[Volv04Life]

My scooby has 205k on it and still "couples Viscously" lol. But seriously it kicks [censored] in the snow especially with the new firestones Ive got. I cant get it stuck. But Ive changed my diff fluids and need new axles cuz theyre clanking. So the subaru systems seem to last a good while.

 

[JHZR2]

Is the fluid not replaceable? I would imagine that blades and vanes could wear down a bit... Not sure exactly how the system works though...

 

[147_Grain]

In my 2013 Outback H6 with 5-speed automatic, the viscous coupling is inside the transmission and is serviced whenever the ATF fluid is changed. Grateful Subaru included a drain plug in the transmission oil pan to take care of this every 20K or each spring. Only cost $21.50 for 4-quarts of ATF-HP which is cheap insurance.

Differentials are serviced every 30K with Amsoil Severe Gear Oil (75W-90).

 

[bvance554]

I have a manual transmission forester. It started the torque binding at about 100k. I had the transmission replaced at 147k because it was dead in the water. Apparently manual transmission sube's aren't the most durable. I can't speak for the auto's. in the manual the viscous coupling is sealed and its lubrication is separate from the transmission fluid.

 

[buster]

Yeah the trans and VC are different. The 4EAT is reliable as are the MT's.