# Priming hydraulic pump



## Mike Nicolen (Jan 9, 2021)

I had to take the lines off my hydraulic pump to get to the starter and now my hydraulics don’t work. How can I get it going? Thanks in advance for the advice!


----------



## Tx Jim (Jul 28, 2020)

Welcome to Tractor Forum
It would help to know what type tractor hyd pump is mounted on. 

One can apply short bursts of low pressure compressed air into hyd reservoir filler opening with the intention of forcing hyd oil into hyd pump in order to prime pump. Also loosen hyd pump pressure line could possibly allow pump to prime.


----------



## Groo (Jan 17, 2020)

yup. air can stop up the works. crack the pressure line. pneumatic pressure into the inlet should be kept very low, like 5psi tops. easy to take out a shaft seal and hurt some of the internals. most pumps aren't made for that at all. they are expecting a slight vacuum, not pressure..


----------



## Mike Nicolen (Jan 9, 2021)

Tx Jim said:


> Welcome to Tractor Forum
> It would help to know what type tractor hyd pump is mounted on.
> 
> One can apply short bursts of low pressure compressed air into hyd reservoir filler opening with the intention of forcing hyd oil into hyd pump in order to prime pump. Also loosen hyd pump pressure line could possibly allow pump to prime.


Thanks for replying. This looks like a pretty active and relevant forum. 
It’s a 2005 TYM T273. Should I loosen the low pressure line or high pressure line?


----------



## Groo (Jan 17, 2020)

high pressure line.


----------



## Tx Jim (Jul 28, 2020)

Groo said:


> yup. air can stop up the works. crack the pressure line. pneumatic pressure into the inlet should be kept very low, like 5psi tops. easy to take out a shaft seal and hurt some of the internals. most pumps aren't made for that at all. they are expecting a slight vacuum, not pressure..


Please explain how short bursts of "low pressure" air are going to blow out any seals that are normally designed to withstand 2000+ psi! Most open center pumps are gear type which I can't envision how even higher air pressure can harm them.


----------



## Groo (Jan 17, 2020)

Tx Jim said:


> Please explain how short bursts of "low pressure" air are going to blow out any seals that are normally designed to withstand 2000+ psi! Most open center pumps are gear type which I can't envision how even higher air pressure can harm them.


they are not designed to have pressure there at all. they are designed to be pulling a slight vacuum there. now, it doesn't take much to allow them to handle pressure there (basically set them up in a motor configuration), but most pumps are not set up for a pressurized inlet. They are designed to see pressure at the outlet. The first sign of failure that pops up (in my experience) from pressure where it isn't supposed to be is the shaft seal leaking; but by then, damage has been done to the internal too.
eta: "bursts" are the worst possible way to apply pressure to the pump inlet.


----------



## Bob Driver (Nov 1, 2017)

Working on trash trucks.... I used to disconnect the pressure feed line at the main valve body and plumb it through the hydraulic PM "filter buggy" to prime the circuit all the way from the pump to the main valve inlet. Most guys don't have a $3,000 filter buggy laying around, so you got some sort of electric suction pump that you could plumb to do the same thing?


----------



## Mike Nicolen (Jan 9, 2021)

I just tried this trick and it didn’t work. The tractor actually has 2 pumps in line. 1 is for hydraulics and the other is for HST. I hope running the tractor with a dry pump didn’t ruin anything but I had to move it. The HST worked, but very slow. I backed it up about 8 feet to get it out of the way (extreme emergency).
Referring to the pictures I sent, i unhooked the top and bottom hoses on the rear pump ( on the right) when I removed the starter. The bottom hose I assume to be the high pressure one. The front pump has a similar hose that can’t be seen from this view. Do I need the tractor running when I put air pressure to the reservoir?


----------



## Fedup (Feb 25, 2014)

Assuming the hydraulics and steering worked before the starter issue, one would expect they would work after as well. Judging from the photo my first thought would be a thorough cleaning would be in order first off. Next, I would remove the suction pipe and inspect the O ring under it. If at all possible, replace it. Then using whatever means available (squirt can, syringe, squeeze bottle) put as much oil as possible into the pump inlet to insure the gears are good and wet. Fill the opening to the top if possible before installing the pipe. Loosen the pressure line below a thread or two then start the engine. Be ready to shut it off quickly if the pump goes to work and starts spraying fluid. You might also tighten the hose clamps a bit more. I use a 1/4" drive socket/ratchet since I can't seem to get enough torque with a screwdriver any more. Advanced age has multiple drawbacks. 

A quick search brought this up. Maybe you already have this, maybe not.

https://static1.squarespace.com/static/5827738c893fc0eadc600d63/t/5866e6632994ca4cb3333f43/1483138685207/T233HST,T273.pdf


----------



## Groo (Jan 17, 2020)

Their should be a breather cap for the hydraulic reservoir. That is where you would need to put the air, otherwise it will leave there.

I doubt you hurt anything on the gear pump as their should still be an oil mist. The charge pump for the hydrostatic might be another matter. Those are usually vane pumps from what I've read. They are very prone to cavitation. Its likely cavitating if it's just barely moving.


----------



## Tx Jim (Jul 28, 2020)

Groo said:


> Their should be a breather cap for the hydraulic reservoir. That is where you would need to put the air, otherwise it will leave there.
> 
> I doubt you hurt anything on the gear pump as their should still be an oil mist. The charge pump for the hydrostatic might be another matter. Those are usually vane pumps from what I've read. They are very prone to cavitation. Its likely cavitating if it's just barely moving.


Groo
1st reply you state utilizing air to prime hyd pump could blow seals & ruin hyd components & short air bursts are worse than constant pressure . Then you reply stating where for Mike to apply air pressure to his tractors hyd reservoir. Which side of this fence are you going to stand on? 

May I ask where you acquired your hyd repair education? 

I was employed at a farm equipment dealership for 21 yrs & custom farmed since 1987.
Thanks, Jim


----------



## Groo (Jan 17, 2020)

I said be cautious with it, but if you are running out of options, you gotta do what you gotta do.

maybe use a shop vac instead of a compressor.

As to where I picked up the knowledge about what pulsing low pressure to an inlet does to a pump, I got it from the engineering department of a major hydraulics supplier to explain the mountain of failed pumps. I was seeing pulses of just over 10psi.


----------



## Tx Jim (Jul 28, 2020)

IMHO pulses in hyd pump supply oil & short bursts of air into hyd oil reservoir opening in an attempt to force oil to prime pump won't cause similar problems.

May I ask what type machine the mountain of pumps were failing on?
Thanks, Jim


----------



## Groo (Jan 17, 2020)

the pulsing is probably what took out the seal, but the wear damage inside was likely just the results of the pressure applied while it was running.


----------



## Fedup (Feb 25, 2014)

What evidence do you have that the seal is "out"? Or for that matter, that there is any appreciable "wear damage inside"?


----------



## Groo (Jan 17, 2020)

well in the case of the pumps I was dealing with, the piles of oil spraying out would be the proof that the seal went out. tear-down reports with photos were the evidence of the internal wear damage.


----------



## Fedup (Feb 25, 2014)

I could be wrong, but I think we're talking about somewhat different situations here. We don't know what pumps you were dealing with, but in this case I saw no mention of oil spraying anywhere, or any lack of performance before lines were moved for a starter repair. Maybe I just missed that. Then again, I'm not sure how much pulsing might have taken place while the starter was off.


----------



## Tx Jim (Jul 28, 2020)

Ditto with what Fedup stated. Lines were removed to have better access to starter. No seal or pump damage was mentioned in Mike's original post.


----------



## Groo (Jan 17, 2020)

I was describing the damaged caused by pressurizing an inlet not intended for it.


----------



## Fedup (Feb 25, 2014)

So how about we just let it ride for now and wait to see what, if anything we hear back on the problem?


----------



## deerecrouse (Oct 10, 2020)

Mike Nicolen said:


> I had to take the lines off my hydraulic pump to get to the starter and now my hydraulics don’t work. How can I get it going? Thanks in advance for the advice!


What I do when priming is a problem is disconnect the pressure line and thumb over end of pressure line and (using a patting motion) this will change the pressure differential and cause a vacuum at suction ( use starter only if you can) it can be messy when it starts to spray. Have another person to stop starting when the pressure comes.. hope this helps


----------



## Mike Nicolen (Jan 9, 2021)

UPDATE: I got it going today. It was the O-ring not being seated right ( Thanks Fedup). I just happened to have one that fit in my extensive collection! After priming it works as good as before.
Thanks for all the help!


----------



## Tx Jim (Jul 28, 2020)

Congratulations! Thanks for update.


----------



## Fedup (Feb 25, 2014)

Watch out for the pulses.


----------

