Repairs HELP - 2004 Exmark CT puking hydro oil

[Firescooby]

Bought mower used. After about 45 minutes, hydro oil starts coming out of hydro reservoir filler cap. Within about 5 minutes, I'll lose right side hydraulics. After it sits and cools it's ok for a little while.

Hydro oil DOES look milky and starts coming out after running about 30-45 minutes. Right motor still seems weak.

The screw that adjusts/ frees hydro motors will only turn about 1/4 turn either way on right motor.

I have done the following:
1) replaced hydro res cap and seal
2) changed hydro fluid and replaced with M1 15W50
3) Replaced suction/feed lines going to hydro motors

 

[RDA.Lawns]

1 of my zmasters did that once. Changed filter fluid and bleed the system . Worked fine

 

[cruzenmike]

The fluid in your drive system will expand when it gets hot which would explain the overflowing from the cap had it been overfilled cold by the previous owner. The froth or foam may be from moisture or air getting into the system from a leak in a connection or hose. There could also be some cavitation or aeration going on due to a failure of the pump or it's internal components. Also, I have been told by more than one reputable ExMark dealer that M1 is no longer recommended for use in our mowers. The formulation of the oil changed a while back (due to epa regulations) which is when ExMark started offering their own hydro oil. Good luck with your fix.

 

[RDA.Lawns]

I have actually never heard the bit about Mobil 1 I may look into that. I've been using M1 for years with no issues on 4 machines. This year I replaced the oldest ones with bobcat.