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hydro fluid change

clay duncan

LawnSite Senior Member
marion n.c.
i have a walker mower and was told by a very good mech. that a person should not change out the oil in the hydros unless the fluid is discolored or has a burnt smell to it. he said he has seen more hydros go out after an oil change and just to forget that you have them. i like to service things on a regular basis and was wondering if this is good advice or not. he said something about if you do change them then the mobile one oil needed to be filtered first. to me this sounds foolish but i wonder what you guys think.... clay

Albemarle Lawn

LawnSite Bronze Member
Usually an unscrupulous mechanic/ do-it-yourselfer.

Common cause: Getting dirt in at the filter base. Built up crud can get into the return circuit if not careful, sending it directly to the pumps.

Or, some schmoe uses the wrong fluid.

Or, air is not bled out of the system properly.

If you don't know how to change your hyrdro properly, 100% properly, you probably are best not to change it.


Fareway Lawncare

LawnSite Silver Member
The hydraulics are a self contained system. Frequent changes increase the risk of introducing contaminants & are unnecessary especially if running synthetic.

Mark P

LawnSite Senior Member
:) I change mine every 400hr, its very simple your manual should walk you right through it, I always let my new filter fill up and then drain system,screw on new filter add fluid make sure the back wheels are off the floor, then slowly push forward on the lever untill the wheel turns, then pull it back in reverse the wheel rotates then do the other side intill the air which is little will bleed out ive never had any problems changing hydro fluid.......Marks Mowing Service