443 air and slow hydraulic proplem

[bobcat443]

hellou. my bobcat doesnt work normally. i change every bad hoses, filter, belt... check main relief and evrything. I took off the engine checked the gear pump, it was loose, i tighten it. there are air and hydraulic lift is slow and jumpy. i am go grazy.. i bought new gear pump and now i used that 5-6 times 15 minutes and it doesnt change better. slow and air even.. everytime when i turn off machine there is a bubbling sounds filter block and hyd.tank. pressure test is ok main relief is now about 1500psi maybe more and every suction line is tighten. i doesnt know what i should do. left drive is ok but right is noise.. maybe there are airlock or something becouse before work pump and new hoses it drive ok. I am from Finland and my English is very bad!!! but maybe all understand what I mean my bobcat problems.. i have read every posts air and fluid leaks and all topics of these faults. but I can not get my machine to work, or I do not know what to do anymore. it cost so much I am not able to buy new parts for nothing..

 

[bobcat443]

there is same bubbling noise after i work machine 5 minutes, if i only drive.. and next day if i only lift and tilt not drive machine its same bubbling and sounds vacuum or something. and both times there is air. if i dont drive and tilt/lift and oil get air are only fault suction line becouse oil only bybass pump-controlvalve-filter and go back pump.. when i change filter maybe i over tight that becouse i tightened it tool. can this damage or clog filter block. and sorry my suck language.. i have to use translators sometime and still i dont understand some things what i read.. that make it difficult to me read this forum.

 

[Tazza]

there is same bubbling noise after i work machine 5 minutes, if i only drive.. and next day if i only lift and tilt not drive machine its same bubbling and sounds vacuum or something. and both times there is air. if i dont drive and tilt/lift and oil get air are only fault suction line becouse oil only bybass pump-controlvalve-filter and go back pump.. when i change filter maybe i over tight that becouse i tightened it tool. can this damage or clog filter block. and sorry my suck language.. i have to use translators sometime and still i dont understand some things what i read.. that make it difficult to me read this forum.

I don't believe the tightness of the filter is an issue.
Air will take some time to get out of the system, but it should be working better by now.
When you replaced the gear pump, did you notice any changes? did it run any better than before?

 

[bobcat443]

I don't believe the tightness of the filter is an issue.
Air will take some time to get out of the system, but it should be working better by now.
When you replaced the gear pump, did you notice any changes? did it run any better than before?

when i buy that machine it work but i dont have experience that machine so maybe that didnt work good..next day i saw air when i use aux hydraulic and then i take motor and everything out and buy new hoses and filter. i didnt change that metall line what goes filter to reservoir, but i tighten that. maybe its little better that new gear pump but llift and tilt is slow and jumpy, there is pressure but maybe no flow, maybe it's because the are air? and charge pressure is good (80psi). when motor run and not hydraulic work there no air, but start again and drive few minutes and shut down and there are air bubbles reservoir. if only tilt/lift but NOT drive, and drive motor seals are bad can they do air in system still? there are small suction "channel" in gear pump axle, can that suck air somewhere drive pump? maybe i check drive motor seal next. if anyone has ideas..

 

[Tazza]

when i buy that machine it work but i dont have experience that machine so maybe that didnt work good..next day i saw air when i use aux hydraulic and then i take motor and everything out and buy new hoses and filter. i didnt change that metall line what goes filter to reservoir, but i tighten that. maybe its little better that new gear pump but llift and tilt is slow and jumpy, there is pressure but maybe no flow, maybe it's because the are air? and charge pressure is good (80psi). when motor run and not hydraulic work there no air, but start again and drive few minutes and shut down and there are air bubbles reservoir. if only tilt/lift but NOT drive, and drive motor seals are bad can they do air in system still? there are small suction "channel" in gear pump axle, can that suck air somewhere drive pump? maybe i check drive motor seal next. if anyone has ideas..

I don't think a drive motor leak could do it, not to the extent you have at least.
That is good charge pressure.
What i did when i started my 743 after a full rebuild was to run it for ony a few minutes, arms up and tilt, back, but avoid the rams hitting the end of stroke as this can cause pump damage from cavetation when your oil pressure spikes. Up down a few times, drive around a little then stop the machine over night.
Repeat for a few days and it should get better. It takes time to get it all out, but it will self bleed if there are no other issues causing the bubbling.
It takes time for the oil to settle out, allowing the foam to turn back in to un-airated oil.
Sadly i don't know your machine well enough to give better advise.

 

[bobcat443]

I don't think a drive motor leak could do it, not to the extent you have at least.
That is good charge pressure.
What i did when i started my 743 after a full rebuild was to run it for ony a few minutes, arms up and tilt, back, but avoid the rams hitting the end of stroke as this can cause pump damage from cavetation when your oil pressure spikes. Up down a few times, drive around a little then stop the machine over night.
Repeat for a few days and it should get better. It takes time to get it all out, but it will self bleed if there are no other issues causing the bubbling.
It takes time for the oil to settle out, allowing the foam to turn back in to un-airated oil.
Sadly i don't know your machine well enough to give better advise.

thanks. its now 5th days i run it while but it is same.. i try couple days more if it better. and then do somethin repairs if that dont go better. you meen if drive motor seals leaking outside or chaincase that doesnt can suck air? there are always only pressure? can control valve anytime suck air? theres too always pressure, its only can leaking outside.

 

[Tazza]

thanks. its now 5th days i run it while but it is same.. i try couple days more if it better. and then do somethin repairs if that dont go better. you meen if drive motor seals leaking outside or chaincase that doesnt can suck air? there are always only pressure? can control valve anytime suck air? theres too always pressure, its only can leaking outside.

It is always possible an external leak could allow air in, but when it is running, there is no suction at a motor or control block to pull in a lot of air, at least not enough to cause the issues you are having.
Your problem sounds like the gear pump is not working right or there is a restriction in the suction line. You have already replaced the pump, so it really shouldn't be the cause of the problem.

 

[bobcat443]

It is always possible an external leak could allow air in, but when it is running, there is no suction at a motor or control block to pull in a lot of air, at least not enough to cause the issues you are having.
Your problem sounds like the gear pump is not working right or there is a restriction in the suction line. You have already replaced the pump, so it really shouldn't be the cause of the problem.

does anyone know the correct diameter suction hose, i dont have old hose anymore and my ny hose are 1/2" but its too little and now there is 5/8" if i remember correct.. my manual doesnt tell which it must be. if that 5/8" its too small between reservoir to gear pump??

 

[bobcat443]

does anyone know the correct diameter suction hose, i dont have old hose anymore and my ny hose are 1/2" but its too little and now there is 5/8" if i remember correct.. my manual doesnt tell which it must be. if that 5/8" its too small between reservoir to gear pump??

anybody know?? 440,443,453 maybe the same suction line size.. Does anyone have a broken or leaking metal tube that goes into the filter tank? if it is able to suck in air?

 

[Ken743B]

anybody know?? 440,443,453 maybe the same suction line size.. Does anyone have a broken or leaking metal tube that goes into the filter tank? if it is able to suck in air?

On hydualic pumps the suction line is allways bigger than the pressure line, on a 443 the inlet hose should be a #10 hose, and the pressure hose should be a #8. I would try to follow the hose from the bottom of the hydraulic tank to the inlet of the pump, look for a kink in the hose, or line, a kink would cause a restriction of fluid going to the pump causing your problem.

 

[Ken743B]

On hydualic pumps the suction line is allways bigger than the pressure line, on a 443 the inlet hose should be a #10 hose, and the pressure hose should be a #8. I would try to follow the hose from the bottom of the hydraulic tank to the inlet of the pump, look for a kink in the hose, or line, a kink would cause a restriction of fluid going to the pump causing your problem.

It is also possible that if the hose is old the inside of it could be swelling up causing a restriction.

 

[bobcat443]

It is also possible that if the hose is old the inside of it could be swelling up causing a restriction.

i know suction line has to be bigger than pressure line, my pressure hose is 3/8" and suction line is 5/8". pressure hose are good i check that and tested.. suction hose is new. i think i change that metall line what goes filter to T fit/reservoir. i dont know where else that proplem are.. i dont know if gear pump can be suck air from drive pump because there is oil space between gear and drive pump. o ring between pumps are new and good. and i have new gearpump. there is no air when only engine runs and no hydraulic action, but when i use tilt or lift sylinder or drive there are air. i think if that metall line suck air somewhere that is easyer when use tilt/lift or drive becouse pump has to be suck much more oil what there rotates.. idont know... i dont understand what you meen that size #8 and #10 ???

 

[Ken743B]

i know suction line has to be bigger than pressure line, my pressure hose is 3/8" and suction line is 5/8". pressure hose are good i check that and tested.. suction hose is new. i think i change that metall line what goes filter to T fit/reservoir. i dont know where else that proplem are.. i dont know if gear pump can be suck air from drive pump because there is oil space between gear and drive pump. o ring between pumps are new and good. and i have new gearpump. there is no air when only engine runs and no hydraulic action, but when i use tilt or lift sylinder or drive there are air. i think if that metall line suck air somewhere that is easyer when use tilt/lift or drive becouse pump has to be suck much more oil what there rotates.. idont know... i dont understand what you meen that size #8 and #10 ???

Since your suction hose is bigger than the pressure hose you are ok there. Something could have gotten in the hydraulic tank and it's partially blocking the hole for the suction line in the bottom of tank.

 

[bobcat443]

Since your suction hose is bigger than the pressure hose you are ok there. Something could have gotten in the hydraulic tank and it's partially blocking the hole for the suction line in the bottom of tank.

when i take engine and everything out of machine i get oil tank too and gleaned that. i dont think there can be anything what can block that line. weekend i change that metall line what goes filter to t fitting/tank.. thanks information. i tell what happened when i get change that line.

 

[7LBSSMALLIE]

when i take engine and everything out of machine i get oil tank too and gleaned that. i dont think there can be anything what can block that line. weekend i change that metall line what goes filter to t fitting/tank.. thanks information. i tell what happened when i get change that line.

without refercne man, goining off the cuff, think been here done it::: found suction leak at filter, OLD SCHOOL TRICK FOR SUCTION LEAKS) pay attention grasshopper, shavining cream. spread on all suspect suction leak will dimple where leak is washes off easy, i may have posted a thread on old school tips and tricks, (lessons learned hard) also note if this is the set up im thinking of there is an (looks like an air chuck) thinghy that you can put a hos on and run back to tank for bleedining,

 

[bobcat443]

without refercne man, goining off the cuff, think been here done it::: found suction leak at filter, OLD SCHOOL TRICK FOR SUCTION LEAKS) pay attention grasshopper, shavining cream. spread on all suspect suction leak will dimple where leak is washes off easy, i may have posted a thread on old school tips and tricks, (lessons learned hard) also note if this is the set up im thinking of there is an (looks like an air chuck) thinghy that you can put a hos on and run back to tank for bleedining,

i took that metall line out today and it seems somebody previous owner is fixed that, maybe that line is suck air or leaking oil before.. idont sure.. i put 500psi oil pressure on the pipe, but it is not leaked to the outside, idont know can that suck air inside??? i put new hose and maybe tomorrow or monday i get everything back and see if it work or no.. i dont know what else can do.. that i want to know where of DRIVEPUMP oil goes to GEARPUMP shaft. there is orifice drive pump and gear pump. if gear pump get air somewhere in drivepump, o-ring between pumps are new and good.. and pumps tight together. I do not know anyone understands my writings..

 

[mrdeere1959]

i took that metall line out today and it seems somebody previous owner is fixed that, maybe that line is suck air or leaking oil before.. idont sure.. i put 500psi oil pressure on the pipe, but it is not leaked to the outside, idont know can that suck air inside??? i put new hose and maybe tomorrow or monday i get everything back and see if it work or no.. i dont know what else can do.. that i want to know where of DRIVEPUMP oil goes to GEARPUMP shaft. there is orifice drive pump and gear pump. if gear pump get air somewhere in drivepump, o-ring between pumps are new and good.. and pumps tight together. I do not know anyone understands my writings..

I remember see one sucking air at the pintal shaft seals.

 

[bobcat443]

I remember see one sucking air at the pintal shaft seals.

pintal?? what that mean??

 

[bobcat443]

pintal?? what that mean??

i change that suction hose, there goes still air.. i take big hose and coupling out drive pump where goes high pressure and when strarting machine oil lost somewhere, i think gear pump little suction hole is connected this?? that explain if drivemotor seal are bad maybe gear pump suck air so far away? if that not correct i dont know what else can do. today i only run machine idle about three times five minutes long.