1951 Case Vac

I purchased a really nice Case Vac 1951 off Craigslist. The seller was the second owner. The lift was stuck up and would not drop. I purchased regardless and brought it home. Since then I have added a new exhaust, rebuilt the carb, and added a new sediment bowl. The tractor runs great. My issue is the lift will lift, fast and strong, but once up, leaks out from under the control lever when I put the lift down. Not only do I lose fluid, but it takes forever to lower. The hydraulic pump is good, but I am not well versed with the lift cylinder or depth control block. Has anyone else had this issue and or resolved it?
 
Your rockshaft housing is likely flooded with oil that has leaked by the piston seal. The vent/leak off tubing conveys any piston seal leakage back to the torque tube. If the tube is plugged or overcome by the volume of oil leaking by the piston seal, the oil in the rockshaft housing leaks out the control lever side since there is no shaft seal on that side. The piston seal may have leaked a little over time and the tubing is plugged or the piston seal is shot. Over greasing those 4 zerks on the back of the rockshaft housing can limit the free space in the rockshaft housing also, the grease can get hard and plug the vent/leak-off.

To check rate of piston seal leak bye disconnect the tubing at the vent/leak-off fitting on the rockshaft. Cycle the hitch up & down about 10 times to clear any residual oil in the housing and to check that the leak off fitting is not plugged. The leak off fitting/tubing can get plugged with old, hard grease, if the rock shaft housing is tight you should be able to feel air puff out as the piston is forced down to raise the draft arms and a slight vacuum when it moves back up. After the 10 cycles, leave the draft arms up with preferably some weight. Any oil dripping from the leak off fitting can only be some residual oil or leak bye of the piston seal. The residual drip will eventually stop and any further oil leaking is the piston seal leak bye rate. A slow drip piston seal leak may not be detrimental for you, but the leaked oil has to have a clear path back to the torque tube.

1951 was the changeover year for the piston with a cup seal to the piston with 2 O-rings. The pistons are interchangeable but the type seal required is dedicated to the piston type and you could have either piston so if you intend to renew the piston seal pull the cylinder and check which piston you have. Do not use the serial nr to determine which piston you have, the tractor is ~65 YO piston could have been replaced either way in the time. Changing the piston seal is an easy, fast fix.

Joe
a237053.jpg
 
Thanks for the quick reply.

Any idea what size those bolts are that hold the lift cylinder to the back of the tractor? Mine are giant Allen head bolts and I will need to purchase a wrench from fastenal to inspection cylinder. The tractor sat for a while, and it wouldn't surprise me that the seals on the cylinder are bad.

Jesse Filion
Keegan Filion Farm
Walterboro, SC
 
Memory is the hex wrench size is 1/2" but not sure and don't have a tractor presently available to check. An easy way to find size if you have an assortment of standard bolts. Select a bolt that the hex head fits in the socket head bolt on the cylinder, the wrench size for that hex bolt is the size socket wrench you need. Eggs ample aa 5/16" hex head bolt is generally 1/2" wrench size, if it is 1/2" wrench size and fits in the socket bolt then you need a 1/2" Allen wrench.

Clear as mud? I am not too together yet this morning.

Joe
 
Had to order the Allen wrench to take off the lift piston's cylinder. No one in town had one over 3/8", alone or in a set. It's supposed to be here tomorrow and hopefully I'll have time to crack it open. I did open the breather tube at the base of the cylinder and it was bone dry. I don't know if that means anything. I'm afraid if I need valves for the depth control, that case may not make them anymore
 
The vent/leak-off fitting is not plugged??? If you cycled the hitch several times with no oil from the fitting and can feel a slight air discharge while raising the draft arms and a slight vacuum when the draft arms are going down then your piston seal is not leaking.

The oil leak when lowering the draft arms can be from a seal in the control block, most likely the release valve. Here are a few pics of the control block. Read the end para of the last pic, 1951 should have the 2 stage release valve if not properly adjusted can account for a slow drop, leak can be a valve seal. You can operate the hitch with cover removed as long as the plunger actuating lever is still in place, that's how you find control block oil leak.

The link is to CaseIH site VAC parts catalog control block internals with part numbers.

Joe
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http://partstore.caseih.com/us/parts search.html epc::mr66944ar691323
 
Disconnected the lower line. Dry. Cycled hitch while tractor runs. No leaks, but slight vacuum...... And I could hear it.

I'm thinking the issue is in the hydraulic control block
 
OK Jesse, that eliminates the piston seal. Moving on to the control block you've probably already done a visual for external leaks like the fittings, the plug on the bottom is the lift check valve has a copper seal. Other than that it is teardown time.

Go to this link and read up on disassembly. Click on the page to enlarge for reading. The site belongs to Mike Johnson, posts as mj. Real nice guy and tractor savvy.

I already gave you a link to the control block parts list, hopefully the parts are still available. As for the seals a hydraulic shop may be able to provide. Note that some of the part nrs have changed over the years and some dealer's have trouble with cross-ref and assume the part is obsolete. I can come up with cross-ref into the mid 1980's. Most dealer's can take it from there. If you think I can help with anything post back and I'll give it a shot.

Joe
http://imageevent.com/skipjack/vamanuals/group7hydraulicsystemsjsessionid eioc5vi3a2.dog_s
 
I forgot to mention the control block is 2 pieces bolted together. The factory gasket is lead. Check for one or more loose bolts when you get into it that far and haven't found the leak.

Joe
 
Unfortunately the link didn't do anything. I plan on tearing it down Sunday. Can the lead gasket be reused or is there an aftermarket?

Also, anyone know where I can find some front mount cultivators and how they hooked up to the lift? I've considered welding a set but haven't seen any good photos to go by
 
I posted the link to mj's VA service manual hydraulic section on YT Case "Classic Forum" which link goes directly to the manual's hydraulic section. You are apparently using YT Case "Modern Forum" and the same link is being redirected to a page for members sign in. Look at that page again and click on the hypelink http://imageevent.com/skipjack/vamanuals and scroll down to the hydraulic section of the manual.

It is possible to reuse the lead gasket if it is in very good condition. It has been many years since I last split a control block. I used bulk gasket material from an auto supply store as lead gasket was not available locally. Thickness of gasket was probably 1/32" very light coat of very tacky, near dry sealant is optional but don't get it on moving parts. There is not likely any need to split the block if the gasket isn't leaking and alignment can be an issue if locator pins were not installed at the factory so just check the bolts.

I don't have any info re front mount cultivators. Start a new post for maximum exposure. There is also an implement forum here at the link, you might want to post there also.

Joe
http://www.yesterdaystractors.com/implment/wwwboard1.html
 

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