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View Full Version : Scag hydros slow down once warm


97firebird
02-24-2007, 06:40 PM
Hey guys, I have been doing a lot of searching but I can't seem to find what I am looking for. My STHM 61" 3-wheel rider runs strong and the hydros work awesome until they are running for about 5 minutes. So they are strong and perfect, then heat up after 5 min, and are slow and weak. I can hear the pump still pumping, but the speed is dramatically decreased especially when going up hills. My question is...Do I have a hydro pump problem or wheel motor problem? How can I check to make sure? From what I have read it is better to just replace the entire motor, since rebuilding isn't more than just seals. Any input would be appreciated. Thank You.

khouse
02-24-2007, 08:20 PM
I would try running 50 weight oil in the hydros. Worth a try and cheaper than new hydro's.

Steppenwolf
02-24-2007, 08:29 PM
A shot in the dark but are your dump valves closed completely?

lucforce
02-24-2007, 11:41 PM
Belt slippage?

Mr Priceless
02-24-2007, 11:49 PM
Belt slippage?


do you know what hydros are?:hammerhead:

lucforce
02-25-2007, 12:11 AM
I believe that a hydraulic motor is one which would be delivered a viscous fluid under some pressure and at some velocity. This pressure and velocity delivered by hoses, tubing or some other conduit, but first created some other portion of the system (less we defy energy balances); this other part usually defined by the general name "PUMP." This pump must be driven mechanically by some method to produce "WORK." Now, to make this "PUMP" "WORK" let us say that an Internal Combustion Engine (I.C.E.) is used to take a combination of fuel and atmospheric gases and convert the stored energy in the fuel through the combustion process and translate the force of the expanding gases of the combustion process acting on the piston and then translated to a crankshaft via a connecting rod. Of course "WORK" can then be done by the crankshaft of the I.C.E. so long as it connected to say, a "PUMP."

Now, if only...we could devise some method to connect this I.C.E. to this pump...

XB 2002
02-25-2007, 07:56 AM
Boy, That was Good !!

MowerMedic77
02-25-2007, 08:08 AM
very nice lucforce:clapping:
the only other thing I may also inspect is if you are seeing air bubbles in your hydro tank, you may have a suction side leak in you hydro system. Start by inspecting all your hoses and their connection at the pumps and also at the line into the hydro filter and also the filter itself. I have seen this issue more then once and the filter was the loose and sucking air around the oring. This will at least give you some easy things to check and eliminate before moving on to more expensive repairs. I hope this helps:)

Restrorob
02-25-2007, 08:49 AM
.


http://www.gtr-game.com/forums/style_emoticons/default/tup.gif :laugh: :drinkup:

jrc lawncare
02-25-2007, 07:07 PM
Belt slippage?Yes!!! A worn out hydro belt will result in slippage, not good when you are looking for maximum output at speed from your hydros. Good post.

97firebird
02-25-2007, 09:45 PM
Thanks for all the great info guys. I will have to do a few things once it warms up, its about 18 degrees here in CT right now.

mpm32
02-26-2007, 09:09 AM
I had almost the same issue with my Scag 3-wheel rider. Mine seemed to be the dump valve. I figured this out while riding along, I pushed down on the dump valve lever with my foot and the mower took off at full power. It just won't stay closed so I used a zip tie to hold the valve closed.

battags
03-03-2007, 11:11 AM
I had almost the same issue with my Scag 3-wheel rider. Mine seemed to be the dump valve. I figured this out while riding along, I pushed down on the dump valve lever with my foot and the mower took off at full power. It just won't stay closed so I used a zip tie to hold the valve closed.


I have the opposite problem. I can never get mine open by hand in the field if I need to pull the mower out of a ditch or something. I ALWAYS have to run back to the truck for some pliers.

I guess, all things considered, I'd rather have mine stick instead of always popping loose.

B

Mic_bug
03-04-2007, 02:03 PM
Have you checked your belt lately?

battags
03-04-2007, 04:09 PM
Have you checked your belt lately?

Only one hole left on mine. Time to start landscaping and get back into shape.....:)