QUESTION: Bobcat 742 won't lift bucket w/ weight

Help Support SkidSteer Forum:

groomergirl

Member
Joined
Mar 6, 2015
Messages
7
I bought a Bobcat 742 with the Ford 1.6L motor in it from a friend a couple years ago. It runs fine and I can scrape the ground but the bucket won't lift with any weight in it. The bucket will lift all the way up empty but put weight in it and it barely lifts an inch. I was told that the hydraulic rams were both rebuilt (that I believe), the hydraulic pump was rebuilt (this I'm iffy on), and I have had the hydraulic control block rebuilt at the Bobcat dealer. I have also replaced all the hydraulic fluid and line. I was wondering if anybody had any idea of what might be causing this? I don't know if the hydraulic pump was actually rebuilt and if it was they may not have flushed the system before putting it back in. Should I have the pump rebuilt or could it be something else?
 

OldMachinist

Well-known member
Joined
May 24, 2006
Messages
2,748
I'd start by putting a gauge on one of the auxiliary connectors and see what the pump pressure is when you engage the auxiliaries with the engine at full throttle. A 742 should have 2200-2400 PSI there. If the pressure is low try adjusting the main relief valve and see if you can get the pressure within range.
 
OP
OP
G

groomergirl

Member
Joined
Mar 6, 2015
Messages
7
I'd start by putting a gauge on one of the auxiliary connectors and see what the pump pressure is when you engage the auxiliaries with the engine at full throttle. A 742 should have 2200-2400 PSI there. If the pressure is low try adjusting the main relief valve and see if you can get the pressure within range.
The pressure is 1500 psi. This morning when I first started it up I was able to get the bucket all the way up but once it was warm I can't get it to lift any further than it can tilt. If I lift up on the bucket while someone tries to put it up, it goes up and it stays up as far as I push it.
 
OP
OP
G

groomergirl

Member
Joined
Mar 6, 2015
Messages
7
The pressure is 1500 psi. This morning when I first started it up I was able to get the bucket all the way up but once it was warm I can't get it to lift any further than it can tilt. If I lift up on the bucket while someone tries to put it up, it goes up and it stays up as far as I push it.
Where is the pressure relief valve?
 

OldMachinist

Well-known member
Joined
May 24, 2006
Messages
2,748
Depends on the machine serial number and which control valve it has. Post the serial number and I'll try to find the adjusting procedure.
Something else I meant ask. With the bucket down flat can you use the tilt down will it lift the machine or do the arms go up?
 
OP
OP
G

groomergirl

Member
Joined
Mar 6, 2015
Messages
7
Something else I meant ask. With the bucket down flat can you use the tilt down will it lift the machine or do the arms go up?
Unfortunately the spot where I believe the plate with serial number went is empty and you can tell there used to be a plate there. I know that it's a 80's Melroe Bobcat 742 with a Ford 1.6L engine. Here are some pics. I can use the bucket to push down and lift the front of the Bobcat for 20-30 seconds but then the Bobcat drops back down. http://chico.craigslist.org/hvo/4920897104.html
 

antfarmer2

Well-known member
Joined
Oct 28, 2013
Messages
2,801
Unfortunately the spot where I believe the plate with serial number went is empty and you can tell there used to be a plate there. I know that it's a 80's Melroe Bobcat 742 with a Ford 1.6L engine. Here are some pics. I can use the bucket to push down and lift the front of the Bobcat for 20-30 seconds but then the Bobcat drops back down. http://chico.craigslist.org/hvo/4920897104.html
Whe your standing in the bucket with the cab up is there one big hose going to the left of the pump or a steel block with three lines comming out of it if it is the latter take the center one off then take the nut off the block and you will find a bronze filter there clean it out good
 
OP
OP
G

groomergirl

Member
Joined
Mar 6, 2015
Messages
7
Whe your standing in the bucket with the cab up is there one big hose going to the left of the pump or a steel block with three lines comming out of it if it is the latter take the center one off then take the nut off the block and you will find a bronze filter there clean it out good
There is one big hose coming out of the hydraulic pump
 

OldMachinist

Well-known member
Joined
May 24, 2006
Messages
2,748
Did you put a new hydro filter on?
If the machine is a later model then the control valve should look like this.
 photo controlvalve3_zpsc3fkgrfu.jpg


The main relief is where I put the red circle.
 

OldMachinist

Well-known member
Joined
May 24, 2006
Messages
2,748
Found it look down the list 743 hydro pump
If you adjusted the relief valve all the way in and the pressure didn't come up then it's very likely that the gear pump is the problem. The only sure way to know is to have a flow/pressure test done. From all the work that's been done it sounds like someone has been chasing this problem for a while. Has been used enough after all this work to make all the air is out of the system?
 

Latest posts

Top