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1994 cat 928f rear end leaking?

Nige

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No I didn’t not do exactly what he said. I drain it and did not want to start it or touch the brake to see if it leaks sitting.
By not going through the procedure I suggested above you did not remove any residual pressure in the brake system between the cab and the axle, so there is no way of telling how much pressure you had in the system that could cause oil to leak into the rear axle. Just saying.
 

Nige

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As an aside, does a Cat loafer have recirculator pumps, screens, and coolers like my later Deeres? If the recirculate pumps are hydraulic driven, could that be the source?
Is there a rear differential lock, and, if so, is it hydraulically activated? Could that be a leak source?
It would seem as if the easiest course of action is to disconnect the brake feed to the rear axle and pressurize the brakes with a porta power. Someone else will chime in if the pressure for testing should be 750 psi or not.
Axle oil cooling is optional on some Cat loaders but not on this particular model.
No differential lock fitted.

The cutout pressure for the brake accumulator charging valve is 2100+/-50psi. Pressure testing with a Portapower to anywhere over 500psi and watching the pressure decay IMO would indicate whether the brake piston seals were leaking big time or not.
 
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brendin

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I didn’t have time to do all that when I was there. I’m going to try today. But if there was no leak wouldn’t there always be pressure from the cab to the axel? So by pressing the pedal till the pressure is gone am I not just pushing all that fluid into the axel from the brakes?
 

kshansen

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It would seem as if the easiest course of action is to disconnect the brake feed to the rear axle and pressurize the brakes with a porta power. Someone else will chime in if the pressure for testing should be 750 psi or not.

I was thinking about that too! Pump up to even 300 psi and see if it drops off. With the reported leaking I'm thinking just trying to build any pressure will not be easy!
 

Nige

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I didn’t have time to do all that when I was there. I’m going to try today. But if there was no leak wouldn’t there always be pressure from the cab to the axel? So by pressing the pedal till the pressure is gone am I not just pushing all that fluid into the axel from the brakes?
The idea is to release pressure from the brake hydraulic system accumulator THEN drain the axle oil to the correct level and monitor the level for a couple of days.
And my apologies - I got the sequence the wrong way round (I set to set the axle oil level then release brake pressure) when I told you the first time.
 

brendin

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No worries. I’m going to run it for a bit in the next couple days then I’ll pump the brakes till there feels like there is no pressure then I’ll set the oil. Now if it is still leaking oil into the axel is there anything else that could be the problem or is it my brake seals and I just need them fixed.
 

brendin

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Ok guys so Ive decided to just re build the brake seals and see if anything else needs and work in the axle. im going to be keeping this loader for a few years to come so the investment is worth it to me. now i need some help with a service manual. Or if you guys could give me some guidance on how to get the rear axle removed. Serial number for my machine is 2xl00721. 1994 Cat 928F. I have lots of big lifts and equipment to move everything around and lots of blocking to safely get the machine up. Any help would be awesome. Thanks.
 

kshansen

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Guess my question would be are you just wanting to get the axle out or do you plan on attacking the problem yourself? If just needing to drop axle start a conversation with me and I'll see how big a file that would be.

If you are planning on keeping this machine for a "few years" it may be to your advantage to invest in a service manual for it.

You can go to "https://www.servicemanualpro.com/" and do a search under your serial number and down load a manual for $410.00. or order a paper version for $672.00. I believe there is someplace in that process where it will ask you to"Log on" but there should be an option to "Continue As Guest".

I think the $410.00 will seam cheep compared to what the dealer will be asking just to disassemble and reseal that axle and even if you do still let them do that work I would guess that over the next several years the book will pay for its self.
 

brendin

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for now im just planning on getting the axle dropped out of the machine. A friend of my dad works at cat here and is going to give me a great deal on rebuilding it depending on what is all wrong. I will be purchasing that service manual asap. there a huge help. how do i start a conversation with you? im pretty new on here not sure how it all works. thanks.
 

brendin

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Well I got the rear axle out today. Took about 2.5 hrs not to bad. It’s going to cat on Monday I’ll let you guys know how much she sets me back in the wallet.thanks for all the info in here.
 

kshansen

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Well I got the rear axle out today. Took about 2.5 hrs not to bad. It’s going to cat on Monday I’ll let you guys know how much she sets me back in the wallet.thanks for all the info in here.
Hoping it's mostly a handful of seals and orings and a bunch of labor and no major hard parts.
 

brendin

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Well guys I just got a call from cat. Brake seals were completely shot. And the brake discs were pretty worn so I replaced them. Everything to be fixed is about 3700 Canadian. She’ll be good as new now.
 

Nige

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A bit less than the CAN$10k that I think was originally bandied around for the repair - maybe that included overhauling the diff as well. You must be pretty happy.
With only 5200 hours it's likely that's the first time that rear axle has ever been out. Now all you have to worry about is the brakes on the front ………
 

brendin

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Yeah it was a good price. The 10k was for a total over haul. They said everything looked really good otherwise. They said I could of left the brakes and they would of lasted a little longer but I figure while it’s out and there i paid all the labour already so figured I’d get them done.
Thanks for all the help.
 

Nige

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No point going in there and not doing the brake discs at the same time as replacing the failed piston seals.

What type of oil are you planning on putting into the axle once you get it back in the loader again.?
 
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Nige

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Usually the brakes on the front axle wear faster than those on the rear because of the weight transfer to the front. So either the front brakes have already been done by now, or if not and they have worn more than the rear ones they’re just about on the point of letting go.
 

kshansen

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No point going in there and not doing the brake discs at the same time as replacing the failed piston seals.

What type of oil are you planning on putting into the axle once you get it back in the loader again.?

Speaking of the oil to be used doesn't this machine also need to have additive added to the axle oil for the wet brakes?
I thought I saw reference to that at one point but can't seem to find that information again! Believe it called for .5 liters of the additive.

EDIT>>>>>>>>>>>>>>
Did some more digging and found part of what I was looking for in the section in the maintenance manual on changing the axle oils:
4. Add 0.5 L (.53 qt) of oil additive to each axle. See Axle Lubricant in the Lubricant Specifications of the Maintenance Section.

Only problem is I'm not seeing it mentioned in the Lubricant Specifications section.
 
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