oil foaming in resivor 843 bobcat

[EdTrefger]

i have checked replaced seals in hydraulic pump found nothing wrong then replaced both hoses on inlet side still nothing took main valve body out replaced all seals found three bad o rings checked port block found okay checked tilt block replaced seals re started bobcat have 2200 psi at main pressure line checked pressure at diagnostic coupler and have 235 lbs checked oil tank and hose and doubled clamped after about 10 minutes still foams up checked return line from wheel motor pumps no pressure on this line until handle is moved which is right running out of ideas can any one have an answer of any kind would help thanks for you help -Ed

 

[Fishfiles]

2200 is low , would have to guess the seals were not the problem , the inside of the housing and the end plates are worn letting the pump cavatate , replace the pump

 

[EdTrefger]

2200 is low , would have to guess the seals were not the problem , the inside of the housing and the end plates are worn letting the pump cavatate , replace the pump

to fishfiles my pump is a double stage pump i have main pressure set at 2200 psi on high side low side pump checked at conection shows 235 lbs it replinishes hydrostatic drive i have resealed pump also it came with end plates checked thickness about .003 diference could i still missed it pump did have about .010 on one side last pump about 10 years ago went bad but never caused this to happen i will try anything thank you

 

[jmatt20]

to fishfiles my pump is a double stage pump i have main pressure set at 2200 psi on high side low side pump checked at conection shows 235 lbs it replinishes hydrostatic drive i have resealed pump also it came with end plates checked thickness about .003 diference could i still missed it pump did have about .010 on one side last pump about 10 years ago went bad but never caused this to happen i will try anything thank you

someone posted this problem before ...not sure how it was resolved ..in my case i had an 843 with the same problem ..mine was caused by a cold weather by pass valve in the system ..it looked like a T in the return side of the system with one hose leading to the reservoir...it had something stuck in it holding it just a little open .. causing the oil to squirt into the reservoir return side and thereby foaming ....took me some little time to find the problem ...did all of the checks you have done ..to no good result ....at the time something like an 80/100 dll part

 

[jmatt20]

someone posted this problem before ...not sure how it was resolved ..in my case i had an 843 with the same problem ..mine was caused by a cold weather by pass valve in the system ..it looked like a T in the return side of the system with one hose leading to the reservoir...it had something stuck in it holding it just a little open .. causing the oil to squirt into the reservoir return side and thereby foaming ....took me some little time to find the problem ...did all of the checks you have done ..to no good result ....at the time something like an 80/100 dll part

if any help my 843 was a 1983 vintage don't know what yr of build you have ....

 

[EdTrefger]

if any help my 843 was a 1983 vintage don't know what yr of build you have ....

oil foaming problem solved it was a high pressure problem ; the problem is with the double stage pump the front half of the pump feeds oil cooler and hydrostatic drive motors side case wear was not more than .010 but it created back pressure at port block which caused high pressure causing foaming excess one quick way to find the problem is at diagnostic coupler mine was 235 lbs my other bobcat is only 180 lbs now they are both the same and problem is gone the help from the people that are on the forum sent me looking in the right direction thank all of your time i hope this helps other members thank you eddie

 

[Fishfiles]

oil foaming problem solved it was a high pressure problem ; the problem is with the double stage pump the front half of the pump feeds oil cooler and hydrostatic drive motors side case wear was not more than .010 but it created back pressure at port block which caused high pressure causing foaming excess one quick way to find the problem is at diagnostic coupler mine was 235 lbs my other bobcat is only 180 lbs now they are both the same and problem is gone the help from the people that are on the forum sent me looking in the right direction thank all of your time i hope this helps other members thank you eddie

Good news Eddie , glad you got it figured out ------------I always go by the finger nail guide , if the wear is enough to grab your finger nail when you you drag it over the lip then it is too much , have no idea how many thousands that is , but know is not and doesn't take much to produce air bubbles /cavation