453 gear pump

[dstan359]

Can somebody help me? If my machine drives fine turns fine and backs up fine but when I lift the boom it shimmy's screams and a little and is slow. Can this be a matter of the gear pump? Ihave checked for leaks and there are none. The fluid is full and new, No foam. Should I start with the gear pump replacement?The machine sat for 3 mths and only has 800 hrs Where is the best place to start?

 

[OldMachinist]

When mine was sucking air there was no sign of a leak either. Put a pressure guage in one of the aux hydrualic connections and see what the pressure is when you engage the aux.. It should be 1400-1450 psi. This will give you some insight as to the condition of the hydraulic pump. The best way to check it would be to have a pressure and flow test done. Any good hydraulic shop or the dealer can do the test.
Where is the screaming coming from? Could it be that one of more of the pivot pins have siezed from sitting.

 

[dstan359]

When mine was sucking air there was no sign of a leak either. Put a pressure guage in one of the aux hydrualic connections and see what the pressure is when you engage the aux.. It should be 1400-1450 psi. This will give you some insight as to the condition of the hydraulic pump. The best way to check it would be to have a pressure and flow test done. Any good hydraulic shop or the dealer can do the test.
Where is the screaming coming from? Could it be that one of more of the pivot pins have siezed from sitting.

The bobcat dealer said the flow was 2.5 gpm and the pump needed to be rebuilt @ 1800.00 seams steep seeing I can buy a new one for 1100. they also said air could have damaged the hydro pumps and the gear pump and that # was 6000.00 to fix on top of the 1800. These numbers seam out of control. I got the link from previous guys with the same prob and it seems everything is leading to the pump. I read a guy who did the pump and then had to do thehydro motor seals too . Maybe you could give me a little insight on the cost of this repair. The machine is real nice. Would it be getting air if the dip stick plug was loose too? I tightened thclamp on the filler tube transition clamp too. I'm not a mechanic but can turn a wrench . Building contractor by trade. I appreciate any help. I'm still trying to purge the system. seems like i'ts a little better.

 

[OldMachinist]

The bobcat dealer said the flow was 2.5 gpm and the pump needed to be rebuilt @ 1800.00 seams steep seeing I can buy a new one for 1100. they also said air could have damaged the hydro pumps and the gear pump and that # was 6000.00 to fix on top of the 1800. These numbers seam out of control. I got the link from previous guys with the same prob and it seems everything is leading to the pump. I read a guy who did the pump and then had to do thehydro motor seals too . Maybe you could give me a little insight on the cost of this repair. The machine is real nice. Would it be getting air if the dip stick plug was loose too? I tightened thclamp on the filler tube transition clamp too. I'm not a mechanic but can turn a wrench . Building contractor by trade. I appreciate any help. I'm still trying to purge the system. seems like i'ts a little better.

The original pump spec is 6.8 gpm so I'd have the pump done or do it yourself. You can get the pump out pretty easy and put a rebuild kit in it. But if its got internal damage they don't make the orignal Cessna pump anymore and the only replacement if a little longer requiring either removing the engine/pump assembly or cutting a hole in the side of the machine.
http://www.loaderpartssource.com/bo...at-440-440b-443-443b-450-and-453-7003484.html
Air in the system can do damage but it depends on how long it been operated like this. The dipstick tube being loose should only cause a leak.

 

[dstan359]

The original pump spec is 6.8 gpm so I'd have the pump done or do it yourself. You can get the pump out pretty easy and put a rebuild kit in it. But if its got internal damage they don't make the orignal Cessna pump anymore and the only replacement if a little longer requiring either removing the engine/pump assembly or cutting a hole in the side of the machine.
http://www.loaderpartssource.com/bobcat-parts/bobcat-hydraulic-pumps/hydraulic-pump-for-bobcat-440-440b-443-443b-450-and-453-7003484.html
Air in the system can do damage but it depends on how long it been operated like this. The dipstick tube being loose should only cause a leak.

Thanks old machinist I have been trying to purge the system but no luck. Going after pump next. I found a hydro company that has the original pump in stock.

 

[Sanjv9473]

Gear pump
A gear pump is a type of positive displacement (PD) pump. It moves a fluid by repeatedly enclosing a fixed volume using interlocking cogs or gears, transferring it mechanically using a cyclic pumping action. It delivers a smooth pulse-free flow proportional to the rotational speed of its gears. Gear pump
A centrifugal pump is a mechanical device designed to move a fluid by means of the transfer of rotational energy from one or more driven rotors, called impellers. Fluid enters the rapidly rotating impeller along its axis and is cast out by centrifugal force along its circumference through the impeller's vane tips. Centrifugal pump
Lobe pump
A lobe pump, or rotary lobe pump, is a type of positive displacement pump. It is similar to a gear pump except the lobes are designed to almost meet, rather than touch and turn each other. Rotary lobe pump