# Mtd 990 hydro problem



## Robmc (10 mo ago)

I picked up an mtd 990 this winter and shined it up a bit. It runs great. The 3 point hitch will not raise the tiller. It lifts without the tiller but a bit slow. It lifts the mower but slow also. It does not go nearly as fast as it should and struggles to climb a grade. I changed the hydraulic oil and filter. The 3 point will stay up for hours without the tiller attached. I am thinking my eaton hydrostat has internal problems. Any suggestions other than replacing it with another used one?


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## pogobill (Jan 31, 2012)

Welcome to the forum. Nice looking tractor, hope you can solve your issue here with the help of some of our knowledgeable members.


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## Robmc (10 mo ago)

Thanks Bill. I have an 8n also


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## BigT (Sep 15, 2014)

Do you know which model Eaton Hydrostat transmission your MTD 990 has???


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## Robmc (10 mo ago)

I cannot find the model number on the internet. I would have to remove the trans and clean it to find a number if there is one.


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## Bob Driver (Nov 1, 2017)

I believe it's an Eaton 10 (MTD # 717-168, Eaton # 11868)..... Sounds like a weak charge pump. There are all kinds of Trouble-shooting/test guides on-line for an Eaton 10, they were petty common. Plenty of parts are still available and they aren't that hard to take apart and fix if it's not just a stuck relief valve. There's a test port right above the spin-on filter housing to plug in a pressure test gauge. Depending on what low pressure relief valve you have, it runs anywhere from 220-380PSI


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## TractorRookie (Dec 6, 2021)

Im sorry I cant help you with your hydraulic issue but I just had to to tell you what sweet tractors you have !!! I really want an 8N like that.


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## Robmc (10 mo ago)

Thanks Bob. I got a service manual on line. It says it is a peerless 2503. I will see if there is a port above the filter. I will strip the sheet metal off so I can see the trans and try to find the relief valve


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## Bob Driver (Nov 1, 2017)

Robmc said:


> Thanks Bob. I got a service manual on line. It says it is a peerless 2503. I will see if there is a port above the filter. I will strip the sheet metal off so I can see the trans and try to find the relief valve


The _TRANSAXLE_ probably is a Peerless 2503. The actual hydrostatic unit (it serves to drive the transaxle, and gives you hydraulic pressure for the hitch/accessories) is more than likely an Eaton 10.

See page 88 in the attached Tecumseh/Peerles manual.....

CHAPTER 16. 2500 SERIES HYDRO POWERED TRANSAXLES
GEAR REDUCTION AND DIFFERENTIAL UNIT

GENERAL
_*"Most 2500 Series two speed gear boxes are run by*_
*an Eaton ® *_*Model 10 hydrostatic unit." *_

Is there something like shown in the picture below bolted to the front of the transaxle?

Eaton 10 Hydrostatic unit









Tecumshe/Peerless Transaxle Manual


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## Robmc (10 mo ago)

Yes mine looks like the picture. Thanks


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## Bob Driver (Nov 1, 2017)

Robmc said:


> Yes mine looks like the picture. Thanks


Yep.... Eaton 10 Hydro unit, bolted to a Peerless 2503. Read the Service Manual on the Eaton 10. Pay close attention to the "relief valve" and the "check valves" they are prone to stick if the unit has sat for a long time. You're going to need to tap into the hydraulic pressure and get a gauge reading to know what's going on inside the Hydro unit. A problem with the Peerless is only going to affect the transaxle frunction. A pressure problem in the Eaton will affect both the transaxle and the way your 3-point works


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## SidecarFlip (Mar 25, 2021)

Bob knows....


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## Robmc (10 mo ago)

My service manual says my pump is a marshallmatic m10 model 717-0344. The schematic shows a charge pressure relief valve. (# 56). I cant see that it is accessible through the case


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