843 No/jerky drive forward or reverse.

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phmteck

Member
Joined
Aug 11, 2009
Messages
8
hi guys, I have a 843 with a perkins in it. my problem is that I was using out in the field and unit made a noise and bang i had no hydraulics at all. no forward reverse up , down ,tilt.. nothing. so drug unit into garage started to tear into it and found coupler between engine and motors was totally stripped out.. $600 dollars later and a few dirty words i had a new coupler in.. After a few hours of figuring out where the hoses all connected to on the oil block i was ready to start.. well i started unit and now all i have is bucket up&down , tilt up&down, and auxillary hyd. If I raise the engine rpms. I can get the unit to move sometimes. Mainly with the left side wheels. right side is very weak or non existent. It does seem as if I take and move right stick rapidly back and forth to auxillary bypass i can get the right side to charge up and move erraticly.. To me it seems like air in the system..but the bucket functions flawlessly. I did notice that the hydraulic oil seems to be frothing somewhat. Ive checked hose routing several times but the manual is pretty vauge. Do i have to pre charge hydrauilc motors? i lost about all the oil when i was doing repair.. Any help would be appreciated..I now have a $3800 boat anchor im my shop.. Thanks, Phmteck
 

frogfarmer

Well-known member
Joined
Jul 30, 2010
Messages
359
2 months and still no luck? I followed some of your old posts and suspect your pumps may have sustained some damage from a lack of oil after the coupler install. I have an 843 myself and it self primes after a teardown without any problems. You said its an early 843 but didnt say whether it had the single section or dual section hyd pump. The dual hyd pump has a section for hyd and a section to charge the hydros. Also a concern is you blew a hyd filter; something had to be wrong and may have damaged a bypass valve or spring assm. If the hydros ran without charge fluid the rotating groups in the pumps can scar the plates quickly. Sometimes the scaring can be cleaned up and no big loss besides labor. My first check would be to verify your charge pressure and or flow. If the machine is sound otherwise it is worth well more than $3800. Keep us posted.
 
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phmteck

Member
Joined
Aug 11, 2009
Messages
8
2 months and still no luck? I followed some of your old posts and suspect your pumps may have sustained some damage from a lack of oil after the coupler install. I have an 843 myself and it self primes after a teardown without any problems. You said its an early 843 but didnt say whether it had the single section or dual section hyd pump. The dual hyd pump has a section for hyd and a section to charge the hydros. Also a concern is you blew a hyd filter; something had to be wrong and may have damaged a bypass valve or spring assm. If the hydros ran without charge fluid the rotating groups in the pumps can scar the plates quickly. Sometimes the scaring can be cleaned up and no big loss besides labor. My first check would be to verify your charge pressure and or flow. If the machine is sound otherwise it is worth well more than $3800. Keep us posted.
it has a single section pump.
 

frogfarmer

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Joined
Jul 30, 2010
Messages
359
http://www.skidsteerforum.com/Portals/57ad7180-c5e7-49f5-b282-c6475cdb7ee7/TTTGallery/843/2010_10_05_000829.JPG Can i tee a guage into the front left side port of the oil block.. will be easier for me to get to the the backside of the hydro filter to check charge pressure.
Should be a service port at rear filter housing will look like a male quick coupler only smaller. I will check my manuals to see what if anything may have been damaged by excess pressure. A flow divider valve determines charge volume and a bypass valve determines pressure if I remember correctly.
 
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phmteck

Member
Joined
Aug 11, 2009
Messages
8
Should be a service port at rear filter housing will look like a male quick coupler only smaller. I will check my manuals to see what if anything may have been damaged by excess pressure. A flow divider valve determines charge volume and a bypass valve determines pressure if I remember correctly.
I have searched the filter over, and there is no quick coupler on the base of it...All there is . Is two lines and there is a 3/4" bolt head located at the top filter housing, between the body and the filter.. so do i adapt fittngs to the lines to get pressure readings?
 

frogfarmer

Well-known member
Joined
Jul 30, 2010
Messages
359
I have searched the filter over, and there is no quick coupler on the base of it...All there is . Is two lines and there is a 3/4" bolt head located at the top filter housing, between the body and the filter.. so do i adapt fittngs to the lines to get pressure readings?
Yeah the newer models have the service port. There was a serial number break on the early machines some had a screen in the port block and a filter and some only had a filter. It looks like you probably swaped the main pump pressure line with the line at the port block that goes to the filter (blown filter). If that was the case the hydros had no charge oil as the hyd pump goes to the control valve then back to the port block then out to the hydros for charge oil. That is a very minimal explanation of the oil flow. The service manual take more than a full page to explain oil flow. A clogged screen in the port block could cause a restriction of charge oil. A restriction at the filter could cause a loss of flow. I would open some fittings and verify flow and pressure in the charge circuit as close as possible to the hydro pumps. A guage and adapter fittings is in order. If you have charge flow and pressure the hydro pumps are the problem. Time to remove and inspect the hydro pumps. If you still think you have hoses crossed I would get a set of manuals for you serial number and study the lines and the flow characteristics. The factory manuals are very useful and money well spent. Keep us informed.
 
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phmteck

Member
Joined
Aug 11, 2009
Messages
8
Yeah the newer models have the service port. There was a serial number break on the early machines some had a screen in the port block and a filter and some only had a filter. It looks like you probably swaped the main pump pressure line with the line at the port block that goes to the filter (blown filter). If that was the case the hydros had no charge oil as the hyd pump goes to the control valve then back to the port block then out to the hydros for charge oil. That is a very minimal explanation of the oil flow. The service manual take more than a full page to explain oil flow. A clogged screen in the port block could cause a restriction of charge oil. A restriction at the filter could cause a loss of flow. I would open some fittings and verify flow and pressure in the charge circuit as close as possible to the hydro pumps. A guage and adapter fittings is in order. If you have charge flow and pressure the hydro pumps are the problem. Time to remove and inspect the hydro pumps. If you still think you have hoses crossed I would get a set of manuals for you serial number and study the lines and the flow characteristics. The factory manuals are very useful and money well spent. Keep us informed.
WOOHOO!
i got it to move out of the garage..i had to get fittings to check line pressure, but while i'm waiting i went over the manual as to what could keep drives from working properly. Well i took the relief valves out of the hydro pumps to see if they were messed up in any way.. didn't see anything out of the ordinary, but low and behold the dang thing had both side drives after i put them back in.. now i ran unit for a little bit and the haydraulics seemed rather whiney and then i started to lose right side drive again..are the relief valves a common problem or should i assume the hydro pumps need rebuilt? i only removed the top valves the bottom ones seem like you have to have pumps off to get to. ...oil was still foamy too.
 

Tazza

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Dec 7, 2004
Messages
16,829
WOOHOO!
i got it to move out of the garage..i had to get fittings to check line pressure, but while i'm waiting i went over the manual as to what could keep drives from working properly. Well i took the relief valves out of the hydro pumps to see if they were messed up in any way.. didn't see anything out of the ordinary, but low and behold the dang thing had both side drives after i put them back in.. now i ran unit for a little bit and the haydraulics seemed rather whiney and then i started to lose right side drive again..are the relief valves a common problem or should i assume the hydro pumps need rebuilt? i only removed the top valves the bottom ones seem like you have to have pumps off to get to. ...oil was still foamy too.
The foam is an issue, it shouldn't foam. It sounds like there is still a restriction.
With you removing the relief valves and gaining drive for alittle while sounds like you got out an air pocket but with the restriction, you got air back in.
Its hard to say if you need the pump working on, if you remove it and inspect the wear surfaces this will tell you if its ok or not. There really is no other way to know for sure.
 

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