Great web site. It has helped alot. Here goes my new problem. 4000 hrs on my machine noticed oil on the floor after machine was shut off for a couple of days. seemed real excessive. I used a flexible video cam and verified oil was leaking from rear seal on input shaft with the machine off. Did not notice oil leaking when running. pulled motor and pump. tore pump section apart and replaced seal from bobcat dealer. shaft looked good no grooves. polished swash plates,replaced all hydraulic hoses with new,replaced side seal plates on pump, installed a seperate high flow hydraulic system. lots of extra work. got machine up and running and everthing seemed fine for the first couple of hours. I now have oil blowing up into radiator and cooler. seal seems to be ok when machine is off not dripping. but hard to tell when running I can see some oil slinged off uni-joint. Not sure what to do now. I did all of this extra work figuring it would be a very long time before having machine this tore down. Talk about depressing.
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So oil would be blowing past the pistons? That would explain why I had to replace the o-ring and seal plate on that side. But they were leaking with the machine off. Is there anyway to verify this and any ideas where to get parts?
I'm not so sure if wear in the rotating group would actually cause the seal to leak. The oil that they run in from memory is at charge or lower pressure, they are actually made to leak so they lubricate the shoes. You could check your charge pressure to ensure thats not your problem, remove the pressure sender at the filter and install a gauge that reads 2-300 PSI your charge pressure should be around 120PSI.
It sounds like you have done everything correctly, its just that rotten shaft seal. I assume you bought the kit from bobcat? as i have heard problems using aftermarket seals for the shaft that would leak.
thetool
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- Mar 22, 2008
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Any chance you could have installed your shaft seal backwards?
Only asked 'cause I done did it once or twice on different things......=).
I talked to a bobcat dealer today .He thought it was unlikely the rotating group was blowing by. They never had a failure like that. But if the U-joint happens to go out while running it has a high chance of bending the input shaft on the pump.The other thing they have happen is the 4 steel oil lines next to the pump can wear or rust out and spray oil up into the fan shroud. I am looking at this now it is hard to verify leaks when they are in hard to reach areas.
I did get the seal from Bobcat .My next step will be to check the charge pressure.
Tazza, Which sending unit? Is it on top of the pump the one with two wires ? I found the leak today It is coming from the side seal only when I push the lever full forward.It does not leak in reverse. Is it possible that I am forcing the shaft past its rotation? Also wondering if mabe the taper bearings inside don't have enough preload and the shaft has some play in it ? This only happens in the rear pump not the front pump.
So the oil is leaking out of the pintle arm? the shaft that comes out the side that connects to the steering levers?
There is no way you can move the arms too far, the rotating group limits the trvel. It depends on what pump you have if pre-load is an iuuse, i'm not sure what ones need the bearing pre-loaded as i think some just use taper bearings. That doesn't mean the bearings haven't worn and are allowing the shaft to move enough to allow oil to get past the seal.
The charge pressure sender should be on the back of the pump with one hose going to one side of a T piece that enters the top of the pump. This is assuming you have the newer style pump setup.
Thanks for all the help, I checked pressure today it was around 95 psi. Oil is leaking at the pintle arm only when fully forward. my pump has taper bearings,but on the outside cover plates there is a plastic shim it looks like a gasket at first glance.Maybe I can take the shim out of each side I am gueussing it is the bearings or maybe a bad seal from bobcat?
Its pissible the seal is bad, is there any chance you damaged it when you installed the plate? The *ideal* way is to use cling wrap around the machined part of the shaft to ensure the lips don't get damaged when installing the new seal.
As you said it only happens when pushing forward makes me think the pre-load is not correct due to bearing wear or the shims crushing. I was lucky enough to not have to do this on any of my pumps, they were all the newer style without shims. Is there any way you can get a dial gauge in there to check the end float? then you would know what thickness shim will be required.
The charge pressure is about rite!
