# IH 3500A - Hydro-static questions



## Jan Siegrist (Apr 3, 2018)

Greetings all
I just purchased a 72 IH3500A for real cheap. It seems to run well, although it can be tough to start. The hoe, pads, and front bucket all function.

I got it knowing that the machine would not move, the previous owner had someone start to try and fix it but did not get far. I found one of the small steel lines near the top center of the trans to be completely clogged, and a badly leaking hose on the LH side - center - of the transmission.
I'm in the process of fixing those, frankly I cannot believe it could be that easy. 

According to the PO, the circumstance of the trans failure was, he went to push a trailer, and it would not move, then when he went to backup - nothing moved in that direction either.
He claims he did not hear any grinding noises or feel anything break.
From that point on it has been sitting in a field - six years now.

I'm a total newbie to hydro-static drive systems, I'm currently going thru the manuals but it's tough to get a handle on how it all works.

Generally when something major goes wrong with a hydro-static drive system what is the most common issue(s).

Thanks in advance
Jan


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## BigT (Sep 15, 2014)

Hello Jan, welcome to the tractor forum.

You might get lucky, but when it won't go forward or reverse, it's more likely a major problem. I copied the following comment (post) by Joseph Remesch on the SSB tractor forum:

"* It's probably the forward/reverser clutch. It's a difficult job, at least it was for me. The easiest way is to pull the motor out and pull the clutch pack out through the front of the tranny. 
You can get the parts though. Make sure the clutch is working properly before you put it back together."
*
I question his comment regarding getting parts. It is becoming increasingly difficult to get parts for IH tractors.


*
*


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## RC Wells (Dec 26, 2008)

You are undertaking a complex task.

Spend some time on this website: https://www.herrshydro.com/ The hydrostatic transmission is the same as the IH 574 ag tractor and a number of other IH tractors. Their videos on pressure testing will be helpful.

On the IH hydrostatic transmissions the most common failures are clogged filters and stuck valves from lack of maintenance, worn out TA pump, selector valve and clutch pack failure, broken lines, etc. 

You need a service manual for the 3500A, that manual will give you the pressures required for normal operation of the FORWARD/REVERSE hydraulic assembly and how to troubleshoot the transmission.

Parts are no longer available in normal channels, so you will need to chat with full rebuild service providers like Herrs Hydro, and possibly Steffen Inc.

A bit of advice, do not go shopping the tractor salvage yards for parts, these hydrostatic transmissions are best rebuilt by a professional with a drive bench so they verify they truly are functional and have the updated components that eliminate repeated failures before they roll out the door.

If it is the pump and rotor that is scored, http://www.waterstractor.com has a substitute pump system.

The tractor is the same frame as the IH 674. It was also available with the same 8 speed manual as the 674. It is at times far more cost effective to locate a good 674 and swap components if the operator can live with a manual transmission.


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## Jan Siegrist (Apr 3, 2018)

To everyone, thanks so much for the great information. I do in-fact have the manuals which I've been going thru. Knowing the PO, I would not be at all shocked to find that it was for lack of maintenance. So far I have fixed one clogged line and am getting a hose to replace the one leaking. 
I'll certainly check the pump and anything else I can. I'm sure I'll be posting a lot of pic's as I get into this.
Frankly I know nothing of hydro-static transmissions but in the automotive world I've re-built more than a few old Oldsmobile / Pontiac automatic transmissions. Once I helped a friend swap an automatic trans on an old diesel bus - that was a job...
If worse case and it needs a clutch re-build - any idea what one is worth? Can you get the parts to re-build yourself? I have access to a complete machine shop.
If it is the clutch assembly and I have to pull the motor, that may be ok as it has a leaking rear-main seal.
As far as switching to a manual trans, I'd do that in a heartbeat if the hydro-static parts are not available.

Thanks so much for the info, expect many more questions.

Great group BTW. 

Jan


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## RC Wells (Dec 26, 2008)

Crosscreektractor.com has the 11" Laycock pressure plate and corresponding disc, as does tractorpartsasap.com and Tisco. This firm can locate most parts, some new and others used, http://www.aisequip.com/contact

You are going to want this manual if you go after the internals such as O rings, pipes, reverser, clutch packs, valves, and pumps: https://www.ebay.com/itm/INTERNATIO...KHOE-SERVICE-REPAIR-SHOP-MANUAL-/182157149981 It provides the transmission detail the repair manual does not.

If your local machine shop is experienced with hydraulic pump rebuilding they should be able to handle the charge pump (usual pump that fails). I would expext the price to be over $1,000 for the work. If they are not experienced, you will just spend money and end up with a downrigger weight. I would try Herrs Hydro first.

The internal clutch pack components (discs, steels, seals) are a snipe hunt. Again, Herr Hydro will get you an answer.

I have one of these systems for supporting a split tractor, does require a 6 inch minimum reinforced concrete floor, but safe: http://klineind.com/documents/AT31000-200.pdf Some work through the front and top of the transmission after removing the loader and engine, but I find that inordinately difficult and time consuming (adds week or more to job).

Good luck.


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## Jan Siegrist (Apr 3, 2018)

Hi All,
To RC Wells, thanks for the link for the hydro manual, that was missing from the ones I have, I do have the parts and service manuals for the engine but the hydro manual is what was missing.

I have since found more information on the machine, it does in-fact have a blown hose along side the transmission, I'll be fixing that shortly, also from a friend of the PO, he states that the actuator lever connected to the two foot pedals was very difficult to move and the forward pedal took a lot of force to get it to move.
Off hand do you know if it's safe to remove top cover and check things out? Is anything going to 'fall in' ? I'm currently waiting for the manual.

One manual I do not have is the owners manual - any links on where to get one of those would be appreciated.

and a newbie question, does the hydro-static transmission have it's own oil source?

Thanks in advance

Jan


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## RC Wells (Dec 26, 2008)

The top of the transmission can be removed, not particularly difficult, but you want it clean before you remove it, and where no rain or dust will blow in the transmission. When it is opened up, look at the piping that runs inside to make sure there are no cracks.

The transmission is filled with oil that lubricates and serves as the hydraulic fluid. Most universal tractor fluids are approved for this application, the standards met will be on the label.


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## Jan Siegrist (Apr 3, 2018)

Thanks again for the reply, so the hydro-static transmission has it' own oil separate from the main fill of hydraulic oil behind the seat correct? How do I check the level of that? Also what kind of oil is required by the hydro-static drive transmission? Does it have a filter than can be replaced or cleaned somewhere?

Can I use the $ 40 / 5 gal oil from Tractor supply? Is anyone else using that?
I don't mind spending $ when necessary but at the same time I need to be a bit frugal.

I'm still waiting on the transmission manual but I'm not having much luck finding an owners manual. 

Again, sorry for the newbie questions...

Thanks in advance.
Jan


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## RC Wells (Dec 26, 2008)

It is a common sump in transmission for transmission and hydrostatic pumps and clutches. Case IH recommends their own brand called Hy-Tran Ultra. Nearly all universal tractor fluids carry the same specification, just need to read the label.

I use the cheapest UTF that meets the Case standard in my Case crawler, no problem at all.

Also keep in mind the worst cheap tractor fluid of today is far better than the stuff the equipment dealers sold decades ago. Just need to read the specifications and certifications on the label. Naturally the dealers will specify their own product.


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