So, I noticed a bunch of hydraulic fluid dripping below my fork lift. After a short inspection, I noticed it was leaking from the main pump area. I lifting the hatch over the motor and continued use. The lift functions fully, but when I use the lift features (boom, tilt, steering), it squirts hydraulic fluid from/near the upper bolt hole where the main pump mounts to the engine. This is not the pump for the hydrostatic transmission; this pump is for the hydraulic functions of the lift. I wondered if it was a seal kit, so I called all over the USA for a seal kit. Not available. Discontinued. I did find a couple of the individual parts of the seal kit available, as well as an entire pump ($1100 ). I decided to continue my search. I get in touch with a parts guys who then tells me he's skeptical that its the seal kit. Evidently, there's a Cummins part that fits between the main pump, and perhaps that is cracked. He said that if the seals of the pump were faulty, it would not have any pressure. He was going to check with Cummins. Any help/advice/experience is appreciated. I need a little more info before I have the confidence to order what is needed. I'll list the details of the lift/motor below, including pics: Model: 534C-6 Seriel Number: 0388163 Engine: Cummins 4B39-C Engine Serial: 45266866
I'm skeptical it's a seal kit too. Take it apart and you should be able to see whats wrong easy enough, and see what you need if it's fixable. If you don't want the downtime, you'll need a better answer than I have.
is it squirting hydraulic or engine oil? Check both oil levels to verify. There should be a seal, gasket, oring or some type of seal between the pump face and mounting face on the engine.
If it's a gear pump they can crack
Thanks for the responses. I had a busy weekend and wasn't able to tend to the lift. I'm gonna pull the pump next weekend, and I'll know more at that time. I've been referred to a hydraulics repair company locally, so I'm guessing they can figure it out if it not immediately noticeable.
Have fun pulling that pump. It's a real sob. Seriously, go ahead and have the whiskey ready.
With that type of pump mount, if the shaft seal on the pump is leaking the hydraulic oil ends up in the engine oil. You will "gain" engine oil as you operate. If its the mount seal (oring) you will lose engine oil from the mount face. Make sure its not squirting from between the pump sections.
That's really good info. I'll have to check engine oil to see if hydraulic oil has mixed. What do I look for? It does NOT appear to be squirting from between the pump sections, only at the top mounting hole. What's that mean as I look down over the motor? Totally unrelated, a hydraulic shop said to look for the name of the OEM maker of the pump; with that info, they may be able to get a rebuilt kit for it.
Soooo, apart from the whiskey, how does this thing come off? I assume the headache you're referencing is getting the seal off the shaft? a pry bar all around?
Update: no pics, but I’ve got the hydraulic tank drained and started unhooking other hydraulic lines to get better working room for ratchet and breaker bar on the bottom hydraulic line. Turns out my 24” breaker bar is too much for the 12pt, 2” crowfoot for the bottom hose of the pump. The crowfoot flexes and rounds the edges of the nut. Have to find a wrench type foot or a 6pt socket to get on it better. Worst case, i’ll Have to drag the whole pump out along with a hose or two. I did find out it is a Rexroth pump. Need to look it over for model name/number. As Knepptune states, its a headache. But it ain’t worth the whiskey.
That must be hard :O
Bummed a 2” wrench and got the lower, larger hose off easily. Lightning started striking around me and daylight was waning, so I got out from under the lightning rod I was working on. To be continued....
You tend to work a lot faster when lightning is around. I amazed myself at times on how fast I can actually get something finished in stormy weather.
So, turns out the headache of this things was obtaining the right sized wrenches and the annoyance of having to take off other hydraulic lines, even the oil dipstick. As I pulled the pump off (top pics), a seal (bottom left pic) from the accessory drive (bottom right) was hanging on the pump splines. I fitted it back on/into the accessory drive. It was really loose where it should have been snug and tight. The bearing itself was tight, but I went ahead and took the accessory drive off in case I was only able to obtain a bearing ($265 from Cummins), or worse, a new accessory drive ($675). I'm currently trying to access an "exploded view" of the accessory drive on Cummins to determine if I can getaway with just a new seal. Will be taking the pump to a repair place this afternoon or tomorrow.
Well, not looking good. After a lengthy web chat with a very helpful Bosch Rexroth CSR, looks like I may have two options: 1) Have the shaft seal replaced by hydraulic shop (item 11 in diagram above) if there's no other internal problems and seal can be cross-referenced. 2) Or two, by a replacement Arizona Gear Pump from Bosch Rexroth to replace this one. 3) Buy a Gradall pump for $1100 (was priced that a couple weeks ago)
Okay, so hydraulic shop hasn't gotten back with me, but I've since found a supplier for a replacement pump. HOWEVER, turns out my pump was a special size by Gradall. Evidently, companies do that to keep the OEM parts business going as opposed to putting a standard sized pump. My question at this point is how sensitive are the hydraulic systems/valves/cylinder to the pumps? My Gradall/Rexroth pump has a GPM flow of 11GPM at 1000RPMs and about 21GPM at 2000RPMs. The Prince pumps I've located have below and above those amounts at 9GPM/19GPMs and 10.86GPM/22GPMs, respectively, at 1000 & 2000RPMs. Would the larger pump cause problems? Would the smaller pump fail to do the job?
If everything was working fine, I'd just reseal the pump. Good hydraulic shop , or seal/bearing supplier, should be able to get the seal. There's no reason to put a new pump on it for just a seal leaking.
I 2nd installing a new seal, providing your shaft where the seal rides is in good shape. You can do this yourself very easily...….just make sure you clean everything well, and lay your parts out during disassembly so you can make sure you get everything in its proper place. On a lot of pumps, you can remove and replace the shaft seal without disassembling the entire pump. There is usually an exposed snap ring that holds it in place.
Are you sure you weren't leaking engine oil from the accessory drive seal? Like maybe from tipping the forklift too much and getting oil pumped into the accessory drive by the gear train being submerged, combined with a defective shrunk oil seal??? Doesn't look like anything wrong with that hydraulic pump, if the shop is honest, they'll put it on test stand and tell you it's fine, or not.
Delmer, The oil side isn't pressurized. Yes, the seal was gone out of the accessory drive bearing (pump side) as I pulled off the gear pump. Since 1) the pump seal has no pressure behind it, and 2) the lift only leaked out the top hole when under pressure hydraulic pressure, my neighbor insisted that it is indeed the seal on the pump. At this point in the age of the lift, I think it's a wiser choice to replace the whole pump. They quoted me $486 out the door, which is bearable. Not as cheap as a seal, but having a more reparable pump down the road is the best choice, I think. I mean, even if if the seal job was just a couple hundred bucks, for a couple hundred more, Id rather have one I could get parts for later. I got an accessory drive bearing from Ireland for like, $50 TYD, which was good. Anywhere else it was nearly $300. lol This internet shopping has its advantages. Got the bearing pressed for $20, and picking my new pump up in the morning. Its a Permco pump with the exact same discplacement, 2.5cui, same GPM flow.
Sounds good. I guess I forgot the details, like the thread title.
Got my pump.
You will not know the differance between 11 GPM vs 10.86 GPM
Got'er all put back together and functional. The Permco pump I got was the exact displacement as the factory, so if anyone stumbles across this thread in 10 years, you've got an exact replacement.
where did you buy that pump?