Transmission Pressure

[newinlet]

My 37C has Twin Disc Model MG-506
One of the gears has very high oil pressure the guage is pinned and it works
I know that to much pressure could damage seals. I have a service manuel for the gear and it says that if oil PSI is high the parts from the main regulator valve should be removed and cleaned. It appears to be the parts the shift lever is attached to held down by to screws. Its a spool valve,piston regulator and some springs and a washer. It looks fairly easy has anyone done this. Any advice would be great. I dont want a simple job to turn into a disaster. BTW this is the only remedy for high gear pressure in the guide.
Thanks Jim

 

[Boatsb]

What is high? Mine run about 300-350 PSI. A bit lower when shifting and warmed up.


I was told that was normal.

 

[Dan Mapes]

For our gears (Capitol HE10200's) they recommend draining the oil and filling with Kero. Run about 5 minutes and then flush that out and refill.
It could be you have some burrs jamming up the regulator.

Check your manual again, and change the oil as well. Look for some debris and don't be surprised to find some small stuff. When you lift off the regulator parts go slowly and rock the parts. That way you stand a chance of saving the seals/gaskets from damage. Ditto with the hold down parts. Rock them back and forth to loosen the bolts/nuts and go easy on it.

 

[Blaine Thorpe]

Has it always been high, or did it just change?

First thing I would do is measure the oil pressure with a mechanical oil pressure gage to verify that the sending unit is not the problem.

If it is truly high, then you can look at the valve group. It is easy enough to remove. Just the two bolts. there is some spring pressure behind it, but not alot. You will need a small magnet to get the springs, poppet and shims out.

If it has always been high .... Depending on the vintage of the transmission, the washer you mention is actually a shim(s) used to adjust oil pressure. You maybe able to remove a shim and bring the pressure back in line.

A change of oil wouldn't hurt either.

Blaine

 

[Brian Degulis]

The relief or regulating valve in the valve body is stuck. You remove the entire valve body to work on it. It's pretty simple but definetly get a service manul before you start you will also need some gaskets and seals. If your not comfortable with that just remove the valve body and bring it to a service center.

Brian