Hydrostat issue...with video

[Billy-O]

Originally Posted by sawdustdad

Your Locktite idea is a good one. Red, right? Maybe I should epoxy it, LOL. Locktite makes a super glue version I think.

A copy and paste below.... I think this stuff is green:

Loctite® Bearing Mount 609™ bonds cylindrical slip-fit or press-fit parts to prevent loosening. Excellent for keeping bearings in place in housings or on shafts. Bonds gaps up to 0.005" (0.13mm)

[Ambush]

Loctite makes a cylindrical bonding compound which works good for that. Just be aware that you'll have to use heat to remove the bearing/shaft in the future. And red Loctite requires a lot of heat. Not sure I'd use anything.

Seems you have enough barrel spring pressure. This is a puzzler.

If it wasn't for the shipping cost, I'd say send it to me, I'd love to figure it out. In 28 years there's been a number that we couldn't repair, but I don't think any that we couldn't find out why it didn't work.

EDIT: Billy-O has your number.

[ICOM 756]

iam stickin to the swap the blocks .. your not runnin at 3000 rpms. i dont feel drill would do any damage. the plates look good in your video. i dont see a issue for a test.

[Ambush]

Do you have a spare, stripped out diff housing you could just set on the bench for testing purposes. You only need it for the reservoir. Cover the sides with plates and a square of gasket material. And being a woodworker, you for sure have plenty of clamps to hold them on.

How would switching the blocks show anything? If the pump block assembly is bad, you put it together and turn the input and the pinion does not turn. If the motor block assembly is bad, you put it together, turn the input and the pinion does not turn. If you swap the blocks around, assemble and turn the input and the pinion doesn't turn, you still wouldn't know which one was bad. And how would it turn if one was bad. Unless you are swapping in blocks, one at a time, for known working ones. Or you're saying that the block assemblies are different and just in the wrong place? I can't remember off the top of my head if the piston slippers and or block are slightly different, but I don't think so. And with the physical difference sometimes found, it would still work but be noisy, inefficient and soon fail.

I will add though, that after bench testing thousands of pumps and motors, we have seen cases that totally defied any sense, reason or science. So hey, I guess "why not", nothing to lose but maybe a valve plate or two. This could be one of those mystery cases.


107, you forgot to put the little floppy-doodle thingy's on the end of those pistons. lol

[ICOM 756]

with the way things are goin with this issue.. that it was a working pump then started doing this.. whats to lose..... its for some reason building pressure then letting it go or its not building and then bang full pressure.

anyways ill goto my corner.. ding ding ding

Originally Posted by Ambush

Do you have a spare, stripped out diff housing you could just set on the bench for testing purposes. You only need it for the reservoir. Cover the sides with plates and a square of gasket material. And being a woodworker, you for sure have plenty of clamps to hold them on.

How would switching the blocks show anything? If the pump block assembly is bad, you put it together and turn the input and the pinion does not turn. If the motor block assembly is bad, you put it together, turn the input and the pinion does not turn. If you swap the blocks around, assemble and turn the input and the pinion doesn't turn, you still wouldn't know which one was bad. And how would it turn if one was bad. Unless you are swapping in blocks, one at a time, for known working ones. Or you're saying that the block assemblies are different and just in the wrong place? I can't remember off the top of my head if the piston slippers and or block are slightly different, but I don't think so. And with the physical difference sometimes found, it would still work but be noisy, inefficient and soon fail.


107, you forgot to put the little floppy-doodle thingy's on the end of those pistons. lol

[Ambush]

ICOM, I did edit my post to concede some points. Also sawdustdad is talking about two totally different pump motor combos on the same machine. The added gear pump/motor combo was the one doing the jumping around, I believe?

We've had it where a rebuilt component didn't work on the test bench, The unit is very carefully taken apart, looking hard for clues, find nothing, reassemble and it works fine on the bench.

When this would happen and we would stand around scratching our heads, I'd tell the young guys, "Not everything can be explained, somethings you just have to accept on faith.".


And a tip for removing and installing bearings. In this Sundstrand, the case is aluminum. With a small propane torch heat the out side of the bearing bore to just hot enough you can't keep your finger on it. Aluminum expands at 1.5 X's the rate of steel, so the bearing will be loose even as it heats up. For re-installing, put the shaft and bearing assembly in the freezer for a bit. Warm the housing and drop the chilled bearing into the bore.

For putting bearings on shafts: Put the shaft in the freezer. Grab your wife's iron and set it upside down on low heat setting. A small cardboard box makes a good cradle. Set the bearing on the iron and cover with a clean cotton cloth. Using a clean thick glove slide the hot bearing over the cold shaft. Be prepared to quickly tap or press the bearing if there is still interference.

If you are afraid of your wife (and you should be) you can also set your bearing on a light bulb or heat lamp. Or buy your own iron at the thrift store.

Less friction means easier re&re of bearings and helps prevent galling and shearing from excessive force and cocking in the bore. Especially on aluminum.

[Cubcadet_107]

Originally Posted by Ambush

107, you forgot to put the little floppy-doodle thingy's on the end of those pistons. lol

Yeah, unfortunately for me the little floppy-doodle thingy's aren't supposed to be removable

IMG_20201005_161450.jpg IMG_20210218_191803.jpg

That's the result of someone towing it. Although, I guess it was lucky because nothing was punched through the aluminum casing. Had I been able to locate a replacement block I could've gotten away with a rebuild, but there's no point in taking parts from an already working hydro to fix another hydro. So I replaced the whole hydro and I haven't had an issue since

[ICOM 756]

its all good.. i tossed it out figuring it was a working unit. nothing blew apart that can be seen.. short from the galleys. for me i cant think of anything else . but still learning the pumps. ive seen some things that shouldnt be in the world of motors and such lol .. who knows lol

Originally Posted by Ambush

ICOM, I did edit my post to concede some points. Also sawdustdad is talking about two totally different pump motor combos on the same machine. The added gear pump/motor combo was the one doing the jumping around, I believe?

We've had it where a rebuilt component didn't work on the test bench, The unit is very carefully taken apart, looking hard for clues, find nothing, reassemble and it works fine on the bench.

When this would happen and we would stand around scratching our heads, I'd tell the young guys, "Not everything can be explained, somethings you just have to accept on faith.".


And a tip for removing and installing bearings. In this Sundstrand, the case is aluminum. With a small propane torch heat the out side of the bearing bore to just hot enough you can't keep your finger on it. Aluminum expands at 1.5 X's the rate of steel, so the bearing will be loose even as it heats up. For re-installing, put the shaft and bearing assembly in the freezer for a bit. Warm the housing and drop the chilled bearing into the bore.

For putting bearings on shafts: Put the shaft in the freezer. Grab your wife's iron and set it upside down on low heat setting. A small cardboard box makes a good cradle. Set the bearing on the iron and cover with a clean cotton cloth. Using a clean thick glove slide the hot bearing over the cold shaft. Be prepared to quickly tap or press the bearing if there is still interference.

If you are afraid of your wife (and you should be) you can also set your bearing on a light bulb or heat lamp. Or buy your own iron at the thrift store.

Less friction means easier re&re of bearings and helps prevent galling and shearing from excessive force and cocking in the bore. Especially on aluminum.

[sawdustdad]

I've been sidetracked somewhat working on the dual belt set up, fabbing a tensioner, etc. Making progress. Using this broken hydro as a placeholder for the time being.

Had to order the locktite bearing stuff, and won't get it until Monday. NAPA dropped the ball and lost the can of primer today.

I'm still thinking the displaced bearing and pump shaft is the problem. But I can't, in my mind, visualize exactly how it is causing the problem unless it causes the splines to lose engagement somehow. But I don't know.

I plan to glue the bearing back in place, and run the hydro again early next week. I'll report back. I have a couple spare piston blocks, a few good slipper/pistons, and the cover and charge pump from another hydro. Most of the slippers, retainers, and the main case were damaged from the towing incident (not by me) and not usable.

Late next week--Friday the 26th, I pick up the 1210 and the pair of hydro rear ends. That will put me the first week in March with, I expect, a couple replacement hydros. (I'll keep the 1210 intact now that I've found the other rear ends). I'll swap hydros probably either way, and go from there.

If seating the bearing doesn't fix the problem, I'm not opposed to swapping one of the piston blocks with another one I have from the spare hydro. I'll probably do that on one of the spare rear ends I'm supposed to pick up next week so I can tip it back and remove the hydro without draining all the fluid.

[Ambush]

On the bright side, you'll be a hydro expert by the time you're done.

The saying "experience is something you get, just after you could have used it" is true here too. Good luck!