Heathbar84 Posted June 2 Posted June 2 Has anyone ever done a hydro trans rebuild in the tractor? Have a weak hydro and looking at seeing if I can do it myself. Not seeing a lot of info online about it so I am assuming it’s a task. Thanks Quote
snoshoe Posted June 2 Posted June 2 I have rebuilt a few but never in the tractor. Remove center section same as you would for a ta. Have to ask have pressures been checked to verify it needs rebuilt? There are a number of things that can cause low drive pressure that don't require a rebuild to fix. 2 Quote
Heathbar84 Posted June 2 Author Posted June 2 1 hour ago, snoshoe said: I have rebuilt a few but never in the tractor. Remove center section same as you would for a ta. Have to ask have pressures been checked to verify it needs rebuilt? There are a number of things that can cause low drive pressure that don't require a rebuild to fix. I checked the charge pressure at 1700 rpms, holding the brakes down in forward and reverse goes from 450-470 psi to around 10 psi. New filters and fluid, don’t know exactly what to check next. Quote
HydroTek Posted June 3 Posted June 3 Yes -- testing pressures is a must before tearing into a hydro if you dont know what you are doing -- better take the tractor to Herr's Machine Quote
acem Posted June 3 Posted June 3 Often the hydro itself is not bad but the controls, lines, filters need help. First change both hydraulic filters and fluid to be sure they are not the issue. Inspect the filter media for metal and other contents. Remember to check the hydraulic fluid level with the engine running. If this dosen't fix your problem, you can begin further diagnosis. Quote
snoshoe Posted June 4 Posted June 4 On 6/2/2026 at 6:57 PM, Heathbar84 said: I checked the charge pressure at 1700 rpms, holding the brakes down in forward and reverse goes from 450-470 psi to around 10 psi. New filters and fluid, don’t know exactly what to check next. Three gauges at once. Charge pressure, servo pressure and drive pressure. Your high charge pressure must be with SR lever in neutral. Moving SR to either forward or reverse slot should drop that roughly in half(going over a different regulator as soon as the shuttle shifts). As you slowly advance SR and increase brake pressure. You should see drive pressure rise while charge holds steady or drops slightly until you reach a point where both suddenly drop. If servo pressure remains when this happens. Then oil supply to the pumps is good. If this is what happens. Then you are right. It needs rebuilt. If this is not how it acts report back. Quote
Heathbar84 Posted June 5 Author Posted June 5 6 hours ago, snoshoe said: Three gauges at once. Charge pressure, servo pressure and drive pressure. Your high charge pressure must be with SR lever in neutral. Moving SR to either forward or reverse slot should drop that roughly in half(going over a different regulator as soon as the shuttle shifts). As you slowly advance SR and increase brake pressure. You should see drive pressure rise while charge holds steady or drops slightly until you reach a point where both suddenly drop. If servo pressure remains when this happens. Then oil supply to the pumps is good. If this is what happens. Then you are right. It needs rebuilt. If this is not how it acts report back. Where am I hooking up the gauge for the drive pressure? Quote
snoshoe Posted June 5 Posted June 5 2 minutes ago, Heathbar84 said: Where am I hooking up the gauge for the drive pressure? Tee at back of foot&inch valve to start. Quote
HydroTek Posted June 5 Posted June 5 1 hour ago, snoshoe said: Tee at back of foot&inch valve to start. Charge dropping to 10 psi sounds like the plates are lifting off Betting drive pressure will also be really low ... wonder if the charge filter is the correct one ? -- assume it has been replaced Quote
snoshoe Posted June 5 Posted June 5 1 hour ago, HydroTek said: Charge dropping to 10 psi sounds like the plates are lifting off Betting drive pressure will also be really low ... wonder if the charge filter is the correct one ? -- assume it has been replaced Wouldn't be surprised. If drive pressure builds and then plummets with charge. Then that is what's happening. Quote
Heathbar84 Posted August 3 Author Posted August 3 On 6/4/2026 at 11:39 PM, snoshoe said: Wouldn't be surprised. If drive pressure builds and then plummets with charge. Then that is what's happening. Which would indicate needing to be rebuilt? Planning on splitting the tractor this fall, would love to get the unit to herrs but being in northern Michigan(40 minutes south of the bridge) would be a pain to get it there. I found a shop around Kalamazoo, MI that works on hydros. Just wanting to have some idea what’s going on with it before I drop it off. Quote
snoshoe Posted August 3 Posted August 3 If that is what the pressures are doing. Then the valve plates are worn and pressure is getting between them. Forcing them apart dumping the oil. Hydro will need rebuilt. Other hypressure parts will be worn as well. Quote
acem Posted August 3 Posted August 3 I had a small crack in a pilot operated check valve control line on my Hydro 186. It was inside the housing and hard to find. Caused serious problems but was a cheap fix. If you can't fix it yourself, find someone who knows how to diagnose IH hydros. Although hydrostatic transmissions are common, these tractors are set up different than most everything else. Quote
HydroTek Posted August 3 Posted August 3 Tractor needs to go out to Herr's Machine , about a 12 hour run from you if your rig is not up to the task -- hire it, may be "cheaper" to let some else have the headaches of hauling in the long run anyways Quote
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