743B

Help Support SkidSteer Forum:

ronbrennand

New member
Joined
Nov 29, 2007
Messages
4
No drive power, runs foward and backward on level ground but has no pushing power. Seems to have a little more at full engine power, but tires will not spin. Maybe something simple?
 

Tazza

Moderator
Staff member
Joined
Dec 7, 2004
Messages
16,840
Does it make any noises?
Can you run it trying to drive up a hill or turning for say a minute then feel the pump, is it quite hot?
It all seems like a blocked filter causing cavetation. Do the hydraulics still work fine? It sounds like the old suction line filter is blocked but i was sure the 743B didn't have one of these. Look at the pump, is there a square block with about 5 hoses attached on top of the hydraulic pump or is there a fat hose that goes to the left side of the chassis?
 

sterlclan

Well-known member
Joined
May 1, 2004
Messages
528
Does it make any noises?
Can you run it trying to drive up a hill or turning for say a minute then feel the pump, is it quite hot?
It all seems like a blocked filter causing cavetation. Do the hydraulics still work fine? It sounds like the old suction line filter is blocked but i was sure the 743B didn't have one of these. Look at the pump, is there a square block with about 5 hoses attached on top of the hydraulic pump or is there a fat hose that goes to the left side of the chassis?
three pumps two motors they aren't as complicated as they look I fixed mine for less than a hundred bucks........check the filters and fluid and we can start to diagnose the issues good luck .........................Jeff
 
OP
OP
R

ronbrennand

New member
Joined
Nov 29, 2007
Messages
4
three pumps two motors they aren't as complicated as they look I fixed mine for less than a hundred bucks........check the filters and fluid and we can start to diagnose the issues good luck .........................Jeff
Hi, Thank you for your input, Uphill it make more noise as it slow down, then just stops and squeels. When cold it has more power but still no hill climber. Red hydro pressure light goes on as it stops. Replaced low pressure and high pressure filter and change hydro fluid as cap went missing for serveral months. Leaks may have starved it once or twice, but after replacing seals in hydro wheel motor, system shows no signs of any debri or matel shavings. Is their only one high pressure filter? The one I changed is off the wheel motor relief lines and foward pump. On right side of hydro pump. Top of pump has no lines just a pressure switch mounted on top and one hose from somewhere to it. I wish I could see what is inside of hydro pump. I too think blockage of stick relif valve somewhere, but where?
 

skidsteer.ca

Well-known member
Joined
Jan 20, 2006
Messages
3,853
Hi, Thank you for your input, Uphill it make more noise as it slow down, then just stops and squeels. When cold it has more power but still no hill climber. Red hydro pressure light goes on as it stops. Replaced low pressure and high pressure filter and change hydro fluid as cap went missing for serveral months. Leaks may have starved it once or twice, but after replacing seals in hydro wheel motor, system shows no signs of any debri or matel shavings. Is their only one high pressure filter? The one I changed is off the wheel motor relief lines and foward pump. On right side of hydro pump. Top of pump has no lines just a pressure switch mounted on top and one hose from somewhere to it. I wish I could see what is inside of hydro pump. I too think blockage of stick relif valve somewhere, but where?
The red trans light means you charge pressure is to low. check for the filter on op of the pump that Tazza mentions, its hidden and no one ever check its, if the 743b is the same as a 743 that is likely your culprit.
lowering the loader arms quickly will act as a temporary charge pump and is you case may make the sytoms go away until the boom is down. If thats the case again it points at your chage pressure.
Ken
 

Tazza

Moderator
Staff member
Joined
Dec 7, 2004
Messages
16,840
The red trans light means you charge pressure is to low. check for the filter on op of the pump that Tazza mentions, its hidden and no one ever check its, if the 743b is the same as a 743 that is likely your culprit.
lowering the loader arms quickly will act as a temporary charge pump and is you case may make the sytoms go away until the boom is down. If thats the case again it points at your chage pressure.
Ken
It has to be a charge pressure problem as indicated by the trans light. This could be a blocked filter or a problem with the charge pressure valve. I'm not too sure where the charge pressure is regulated though....
Is there a square block on top of the hydraulic pump with 3 hoses on the left side? This is the hydraulic pump, the one rite at the front of the pumps. Not the hydrostatic pumps that the pressure switch is attached to.
You mentioned a filter on the return line from the hydro motor, did you check BOTH sides? if there is one on the side you worked on, there most probably will be one in the other side too.
Does the oil go foamy? is it white when the machine has not been running? or an off colour. White oil is a sign of water contamination. What grade oil have you been using too? you need engine weight oil, not standard hydraulic oil, its too thin.
 

sterlclan

Well-known member
Joined
May 1, 2004
Messages
528
The red trans light means you charge pressure is to low. check for the filter on op of the pump that Tazza mentions, its hidden and no one ever check its, if the 743b is the same as a 743 that is likely your culprit.
lowering the loader arms quickly will act as a temporary charge pump and is you case may make the sytoms go away until the boom is down. If thats the case again it points at your chage pressure.
Ken
do you have the service manual for your machine? the inside of the pump contains wear plates,rotating group (bunch of pistons in a body) swash plates and pintle levers. Could be a stuck relief but sounds like it is loosing charge pressure like Ken said try dropping the bucket fast when it is groany/squeling and see if that makes it go away for a second. how long was it missing the cap? it is possible that water or something got in and caused wear on the plates inside the pump that is where mine were worn. the post on my repair is here http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=7745and some more info here http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=6618&PageIndex=2 good luck............Jeff
 
OP
OP
R

ronbrennand

New member
Joined
Nov 29, 2007
Messages
4
do you have the service manual for your machine? the inside of the pump contains wear plates,rotating group (bunch of pistons in a body) swash plates and pintle levers. Could be a stuck relief but sounds like it is loosing charge pressure like Ken said try dropping the bucket fast when it is groany/squeling and see if that makes it go away for a second. how long was it missing the cap? it is possible that water or something got in and caused wear on the plates inside the pump that is where mine were worn. the post on my repair is here http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=7745and some more info here http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=6618&PageIndex=2 good luck............Jeff
Hi, Thanks for input. I have manual but not for hydrostat. The manual shows replenishing valves are removable but I have not looked at them yet as I would need to remove the steering rods and clean area, but was not sure these are related. I will try the bucket drop today sometime. Cap missing about 6 to 8 months only a rag was stiffed into fill reservoir. No square blocks on top of hydro pump. only switch. To the right of pump are two blocks with many hoses. One has filter in it (bronse high pressure), that was replaced, and one behind has valve body for attectments, and pressure adjustment ports for bucket, Bucket works good. My friend said he seen the tank seemed airrated, I can not comfirm this. I added a lot of oil and can not see any thing in tank.
 
OP
OP
R

ronbrennand

New member
Joined
Nov 29, 2007
Messages
4
Hi, Thanks for input. I have manual but not for hydrostat. The manual shows replenishing valves are removable but I have not looked at them yet as I would need to remove the steering rods and clean area, but was not sure these are related. I will try the bucket drop today sometime. Cap missing about 6 to 8 months only a rag was stiffed into fill reservoir. No square blocks on top of hydro pump. only switch. To the right of pump are two blocks with many hoses. One has filter in it (bronse high pressure), that was replaced, and one behind has valve body for attectments, and pressure adjustment ports for bucket, Bucket works good. My friend said he seen the tank seemed airrated, I can not comfirm this. I added a lot of oil and can not see any thing in tank.
Hi, Brucket drop test complete, When unit was cold I had no problems with it. It went up hill 5 or 6 times, then it started to slow down and squeel, I lowered bucket and it went forward about another foot then stopped, as the bucket was still lower. It seems to go forward for about a second at the start of each test, then slow to a stop. Down hill no problem.
 

sterlclan

Well-known member
Joined
May 1, 2004
Messages
528
Hi, Brucket drop test complete, When unit was cold I had no problems with it. It went up hill 5 or 6 times, then it started to slow down and squeel, I lowered bucket and it went forward about another foot then stopped, as the bucket was still lower. It seems to go forward for about a second at the start of each test, then slow to a stop. Down hill no problem.
sounds like the same thing that mine did I had worn wear plates in the pump it would foam the oil and loose charge pressure groan and not work. if you decide to fix them yourself I ve got some pictures and pages from the service manual or you could call your"local"dealer and get them to fax those pages to you.the worst part is removing the pump assy. its heavy keep it all clean during reassembly and you should have no problems................Jeff
 

sterlclan

Well-known member
Joined
May 1, 2004
Messages
528
sounds like the same thing that mine did I had worn wear plates in the pump it would foam the oil and loose charge pressure groan and not work. if you decide to fix them yourself I ve got some pictures and pages from the service manual or you could call your"local"dealer and get them to fax those pages to you.the worst part is removing the pump assy. its heavy keep it all clean during reassembly and you should have no problems................Jeff
The bronze filter .......Was it dirty before replacement? wear plate wear is "usually" caused by dirty oil causing the plates to wear where the rotating group rubs them....Jeff
 

Latest posts

Top