# Ingersoll 4120 Onan hydraulic tractor



## Farmergirleh (May 6, 2019)

Need help with my ingersoll onan tractor. Does anyone know about this tractor? Ever since i replaced the mower deck belt dueing mowing it vibrates and loses power especially when turning.


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## RC Wells (Dec 26, 2008)

These have a true hydraulic transmission. As such they are sensitive to having clean oil, the correct oil level and clean oil filter in the drive system. There is a forum for the owners of these units that is quite helpful, and may be able to provide an Operator's Manual: https://casecoltingersoll.com/forum.php
The hydraulic system calls for 20W40 hydraulic oil, but 15W40 T4 Shell Rotella engine oil is often substituted due to cost and availability of hydraulic oil. The oil level should be approximately 4" below the cap to the oil tank.
A parts manual is available online here: https://salempower.files.wordpress.com/2015/05/8-3200-all-hyd.pdf It will help you locate the oil filter for the hydraulic system. The filter itself is available through NAPA, but take your old filter in for a match.


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## Jssec (Oct 6, 2018)

I purchase the same tractor last fall with the same problems.
Told by previous owner it had a bad vibration slow or no power he thought the pump or engine was locking up. So I decided I would separate the pump from the engine to see which was the culprit. What I found is these tractor Do Not have a pump mounting bracket bolted to the engine and then to the pump like a Case. It has a mount that bolts to the fly wheel and the pump shaft goes in the other end and the pump is supported by the pump shaft not the pump housing. The bore in the mounting coupler had worn out allowing the pump to move about off center and vibrate. The coupler is on the left in the 1st photo. I put a new coupler some lock tight and a new key in it all good. 2nd photo is my bad coupler with the worn key way. The flat plate between the couple and the pump keeps the pump housing from rotating. I am working on a 4018 now with the same problem. Is yours power steering? If so it has a Siamese pump like the 1st photo with the power steering pump behind the regular hydraulic pump which would explain the vibrating while turning.














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## thomasvet71 (8 mo ago)

I have a 1993 or 94 Ingerscoll Mode 4120 and iv'e found out that a 10-30 wt. Motor is recommended instead of hydraulic oil.
I did try the AG #32 hydraulic oil and it was way to thin. Say would any one know the length of the hydraulic line for the trotiller?


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## unsquidly (Jul 13, 2021)

thomasvet71 said:


> I have a 1993 or 94 Ingerscoll Mode 4120 and iv'e found out that a 10-30 wt. Motor is recommended instead of hydraulic oil.
> I did try the AG #32 hydraulic oil and it was way to thin. Say would any one know the length of the hydraulic line for the trotiller?



This is an old post................You will have a better shot or getting a reply to just create a new post..........


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