bobcat 853 hydrostatic pump leaks heavy between right and left side

[wateka]

Glad my old wasn't on that tight! I can't recall which socket I used to get the pulley nut off, but I had to order a 28mm socket to torque the pulley nut when I reinstalled it. An 1-1/8" socket would have rounded the nut. Amazon had them for around $8 - GEAR WRENCH 1/2" Drive 6 Pt. Standard Impact Socket, 28mm - 84539N

I did change the in-tank return line on mine. At first I was going to blow it off, because I thought what difference does it make if the fuel splashes into the tank or not. Somewhere on the site I read about eventually losing your fuel prime if there is an air gap.

I wrote the note to myself about the check valve in the hopes that down the road nobody tries to clean out that line with compressed air.

 

[krabill]

Thanks to this forum My 853 is back alive! No major issues putting the pump back together and the engine back in. The M46 pump gasket kit I bought did not have the correct O rings that go in between the right and left side pumps so I had to order them directly from bobcat (as well as the two replacement broken bolts) all this work for two broken bolts! The gasket kit did have most of the other correct O rings and gaskets.

For anyone doing this, it took me about 8 hours for the engine removal a few hours to mess with the pump and then about another 8 hours of it going back in. I did all the work by myself, there is not much room for another person to help anyhow. Also the fancy engine hoist is very nice, but if you only had a forklift that would work ok to pull the engine. BTW, that hydraulic pump is HEAVY!!!!!!!!! I make a makeshift stand for it and lowered the engine/pump down until the pump set on that stand then I took if off from the engine.

Last tip, nowhere in the manual it says to unplug your fuel sending unit wire. I didn't realize it was still plugged in and it snapped off the head of the sending unit when the engine came out. I ordered a new one and it was quite a pain to get the plug in with the engine almost in place but it can be done!

 

[wateka]

Nice work. Bummer on the ripped out plug - a complete oversight on the manual writers. I weighed my unit when it was out - 156 pounds of unwieldy love.

 

[oiu789]

Got my pulley off last night, what a bear! MAP gas wouldn't get it hot enough and had to switch to some light torching then some hits with a hammer and it finally popped off using the good puller.

One question. I bought a new fuel pickup line to replace as was mentioned earlier in this thread. But it looks like there are actually two? One for the primer ball and one for the other fuel line? Should I replace both pickups or just the one (and which one?) I have one pickup line kit now that I bought and it does have the screen at the bottom which seems to match the diagram for the fuel line that has the primer ball. Is that the main one to replace?

Yes the one with the dip tube and screen is the fuel supply replace that one the other is the return and has no dip tube on it it just free returns fuel to the tank. Look at the manual diagrams to see which is witch.

 

[krabill]

Latest update. Played with the machine a bit over the weekend. First thing I noticed was the Red Transmission error light pop up after using the hydraulics for a few minutes (not BOSS equipped) in the good manual it says this
"The transmission warning light comes ''ON'' when hydraulics are operating. (853 Standard)"
Cause 1 - The fluid level is not correct.
Cause 2 - The hydraulic pump has damage.

The Operators manual for this light says:
"Transmission warning light - Low transmission charge pressure, Hydraulic filters needs replacing or high fluid temperature. Stop the engine if light comes one.

So this sounds pretty bad? I have no idea if this light was coming on before I attempted this repair. I shut the engine off and the light goes off, I can start it up, and even idle the the engine up almost max and the light does not come on again, once I start using the hydraulics it will then pop on in a minute or less.

I doubt it's over temp fluid as it happens so fast.
My fluid is full in the Reservoir.
I changed the two hydraulic filters and filled them with fluid before installing them.
I did NOT change the two Silver canister looking "case drain" filters? I think that is their name

has anyone dealt with this light before? Could I still have air purging in my system? I think I've ran it < 10 minutes total since the repair.

Any next steps to take? Are those two canister filters important to change and might cause this? Do I need to do pressure testing? Kind of sad to see this coming on after all this work. I would hate for this to just blow up my pump at this point.

 

[wateka]

Within the 853 model, there are several variations of that warning light getting triggered. On mine (a non-BOSS machine), if the charge pressure is low, or the filters are clogged, or the hydraulic fluid temperature is too hot, then that light will come on. The variations come to play with the type of pressure sensor that you may have (or should have). The BOSS machines have a charge pressure sensor that outputs ohms to feed the BOSS computer. My 853 is not a BOSS machine and had a charge pressure sender that sent out ohms. In following my wiring schematic and the jumble of wires that had been patched over the years there were two wires that went to my charge pressure sender, but only one was being used.

It turns out that if my charge pressure switch needed to be a simple, 3-pole, NO and NC switch. The NC side is wired to the tranny warning light, and the NO side is wired to the hour meter.

If the charge pressure was less than 100psi, the NC side would stay closed and the tranny warning light would illuminate and NO side would stay open, meaning that the hour meter would not be ticking.

If the charge pressure was >=100 psi, the NC side would open, and the warning light for charge pressure would turn off (assuming the temp and blocked filters are functioning normally) and the NO side would close and the hour meter would start ticking.

That's just to help you figure out your possible charge pressure warning light issue.

To see if it is the charge pressure, remove the other wires from the temp sensor and filters first to see if you can isolate the problem.

You should review the electric schematic (it's not terribly friendly unless you have, or know someone who has, a EE degree).

 

[krabill]

Thanks for the tips, I will try and get into it to check the wiring this weekend.

In the meantime, I've seen where others have installed a pressure gauge on some sort of T so they can monitor charge pressure in the system from the cab. Can anyone recommend a kit to do this?