Bobcat 453 -99 Slow hydraulic

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gost

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Hi, last week I bought a Bobcat 453 -99 with only 1000h, but the hydraulic system for lift/tilts is very slow, 12 seconds for full lift, in the manual is says 5sec. The oil looks like whipped milk (when the oil is hot), the driving of the machine is ok, so I guess it must be time for a oli and filter change? or a valve that does not open enough? Please Help.
 

Tazza

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If the oil is milky i'd change it rite away, that sounds like water in the system. It could also be foam from cavetation. Does it groan when you lift the arms or tilt? thats also a sign of cavetation as the oil is being airated. This is not a good thing as when the bubbles implode when put under pressure they can cause pitting on the internal metal surfaces.
 

gost

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If the oil is milky i'd change it rite away, that sounds like water in the system. It could also be foam from cavetation. Does it groan when you lift the arms or tilt? thats also a sign of cavetation as the oil is being airated. This is not a good thing as when the bubbles implode when put under pressure they can cause pitting on the internal metal surfaces.
Hi, the oil looks ok then it´s cold, and after a while it´s full of bubbles, and yes you are correct, it groans a bit when lifting/tilting. After reading many posts here I´ve read it can be the "Bronze Filter". My first plan is to change the oli and filter, is that the first to do?, or shall I also clean the "Bronze Filter"? - (if I can find it)
 

Tazza

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Hi, the oil looks ok then it´s cold, and after a while it´s full of bubbles, and yes you are correct, it groans a bit when lifting/tilting. After reading many posts here I´ve read it can be the "Bronze Filter". My first plan is to change the oli and filter, is that the first to do?, or shall I also clean the "Bronze Filter"? - (if I can find it)
I would personally clean or replace the filter first. You don't want to have to dump clean oil if you need to work on the pump or motors if that turns out to be the problem.
Start with the filter, the square block on top of the hydro pump (well it should be there) Left hand side in the middle behind the middle fitting.
 

gost

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I would personally clean or replace the filter first. You don't want to have to dump clean oil if you need to work on the pump or motors if that turns out to be the problem.
Start with the filter, the square block on top of the hydro pump (well it should be there) Left hand side in the middle behind the middle fitting.
ok, thanks, but in my case the filter looks like regular motoroil filter, round and white - maybe 6 inch high and 4 inch wide, placed in the right side, just inside the wheel. Are we takning about the same filter?
 

Fishfiles

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ok, thanks, but in my case the filter looks like regular motoroil filter, round and white - maybe 6 inch high and 4 inch wide, placed in the right side, just inside the wheel. Are we takning about the same filter?
Hydraulic pump is shot , buubles are from cavataion inside the pump from wear , hook a flow meter / pressure gauge to the aux hyd qiuick couplers and flow the machine to verify it , sounds like you got punked
 

skidsteer.ca

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Hydraulic pump is shot , buubles are from cavataion inside the pump from wear , hook a flow meter / pressure gauge to the aux hyd qiuick couplers and flow the machine to verify it , sounds like you got punked
Gost
Start by changing the spin on filter you found. However there can be other filters in the system that Tazza mentioned. But your model may not have it either.
Cut the filter open and look for steel or aluminum particles inside, if its full of metal, you have somewhat serious problems, ie pump failure, if you find the odd flake here and there inside, that can be normal wear
It can be a leak in the line that supplys oil to the pump (air is getting inside) or a restiction (plugged screen, filter, kinked line, etc) Many hyd systems have a screen between the tank and the pump to keep large forein debris out of the pump
Does the transmission warning light come on when you lift the loader arms. (most skidsteers have a charge oil pressure that must be in the correct range, usually 70 to 100 psi range. If it gets low the warning light comes on. A guage can be installed to verify this, but you need to get the correct pressure from a manual or dealer, Also charge pressure jumps around radically, this is normal, but it should stay within a defined range.
Mechanical failure like a pump, usually gets weaker as the oil warms up and thins out, where on the other hand if its a clogged screen on the suction side, or a pin hole in the suction line the hydraulics Might speed up a bit as the oil thins and flows better.
Hope this helps some, sorry I have no specific experience with that model.
Ken
 

gost

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Gost
Start by changing the spin on filter you found. However there can be other filters in the system that Tazza mentioned. But your model may not have it either.
Cut the filter open and look for steel or aluminum particles inside, if its full of metal, you have somewhat serious problems, ie pump failure, if you find the odd flake here and there inside, that can be normal wear
It can be a leak in the line that supplys oil to the pump (air is getting inside) or a restiction (plugged screen, filter, kinked line, etc) Many hyd systems have a screen between the tank and the pump to keep large forein debris out of the pump
Does the transmission warning light come on when you lift the loader arms. (most skidsteers have a charge oil pressure that must be in the correct range, usually 70 to 100 psi range. If it gets low the warning light comes on. A guage can be installed to verify this, but you need to get the correct pressure from a manual or dealer, Also charge pressure jumps around radically, this is normal, but it should stay within a defined range.
Mechanical failure like a pump, usually gets weaker as the oil warms up and thins out, where on the other hand if its a clogged screen on the suction side, or a pin hole in the suction line the hydraulics Might speed up a bit as the oil thins and flows better.
Hope this helps some, sorry I have no specific experience with that model.
Ken
Ok, thanks all, tomorrow I´ll buy a new filter, and replace, and inspect the inside of the old filter - I´ll report the result here.
 

Fishfiles

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I don't think you will see very much in the filter if you cut it open , the side plates that fit against the ends of the gears inside the pump get a groove worn in them which cause the cavation and lost of pressure , if the machine wouldn't lift at all I would think maybe you would find a some junk , being that you are slow indicates to me it's a flow and pressure problem , as flow gives you speed and pressure gives up power , a 453 only puts out 6.8 gpm at 1450 psi @3000 rpms , not very much available to lose before the effects are felt , get access to a flow meter and you will know in 2 minutes where to look , otherwise you will probally be throwing ice cubes at a fire and the ice cubes are will be expensive
 

gost

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I don't think you will see very much in the filter if you cut it open , the side plates that fit against the ends of the gears inside the pump get a groove worn in them which cause the cavation and lost of pressure , if the machine wouldn't lift at all I would think maybe you would find a some junk , being that you are slow indicates to me it's a flow and pressure problem , as flow gives you speed and pressure gives up power , a 453 only puts out 6.8 gpm at 1450 psi @3000 rpms , not very much available to lose before the effects are felt , get access to a flow meter and you will know in 2 minutes where to look , otherwise you will probally be throwing ice cubes at a fire and the ice cubes are will be expensive
The thing is that I have power, but it´s slow and the oil is full of bubbles. The machine hauls a bit when using tilt/lift, but the driving of the machine is ok, can it still be the pump? I think it´s a filter issue as Tazza describes, or a air suction problem.
 

Fishfiles

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The thing is that I have power, but it´s slow and the oil is full of bubbles. The machine hauls a bit when using tilt/lift, but the driving of the machine is ok, can it still be the pump? I think it´s a filter issue as Tazza describes, or a air suction problem.
It could be anything , I am just going by what your saying and what I have seen in past experiences and fell it's a high 90 's % it a pump problem , a hydraulic filter from my experiences hardly ever fixes a problem other than a filter change time sensor going off or a leak from the filter itself , the filters on almost all machines are on the return side and have a by pass valve which would let it flow if there was a bad clog in the filter , if not you would see filters blowing apart , ---------and if you have the flow meter it is the place to start on a problem like that , snap into the quick coupler and see whats there , you said that both the tilt and the lift are effected that would rule out inter piston seals , which could cause a funtion to be slow but would also allow the cyclinder to bleed down
 

Tazza

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It could be anything , I am just going by what your saying and what I have seen in past experiences and fell it's a high 90 's % it a pump problem , a hydraulic filter from my experiences hardly ever fixes a problem other than a filter change time sensor going off or a leak from the filter itself , the filters on almost all machines are on the return side and have a by pass valve which would let it flow if there was a bad clog in the filter , if not you would see filters blowing apart , ---------and if you have the flow meter it is the place to start on a problem like that , snap into the quick coupler and see whats there , you said that both the tilt and the lift are effected that would rule out inter piston seals , which could cause a funtion to be slow but would also allow the cyclinder to bleed down
These problems can be a real pain to find. It really does sound like a restriction of the suction line filter BUT with that said, not all pumps run these filters. It could be worn seals allowing air to enter the system.
Do you have any oil leaks? leaks can allow air to be drawn into the system too.
Its a good idea to cut the spin on filter to see what is going on, i use a large bipe cutter for this, it open the filters up like a can opener!. The problem with the suction line filters is they are generally hidden. They aren't easy to find as they aren't the spin on type that is easily seen.
 

gost

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These problems can be a real pain to find. It really does sound like a restriction of the suction line filter BUT with that said, not all pumps run these filters. It could be worn seals allowing air to enter the system.
Do you have any oil leaks? leaks can allow air to be drawn into the system too.
Its a good idea to cut the spin on filter to see what is going on, i use a large bipe cutter for this, it open the filters up like a can opener!. The problem with the suction line filters is they are generally hidden. They aren't easy to find as they aren't the spin on type that is easily seen.
Today I visited the local Bobcat store, and they recommended me first to check/tighten all bolts on the Hydrostat. Another tip was to change oil to Agrol Turbo kombi Sae 10w/30 (www.agrol.se). So this is my plan today. I´ll be back.....
 

gost

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Today I visited the local Bobcat store, and they recommended me first to check/tighten all bolts on the Hydrostat. Another tip was to change oil to Agrol Turbo kombi Sae 10w/30 (www.agrol.se). So this is my plan today. I´ll be back.....
Forgot to answer, no no leaks at all.
 

OldMachinist

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Forgot to answer, no no leaks at all.
I have a 453 and had the same problem. See the the link below.
http://www.skidsteerforum.com/DesktopDefault.aspx?tabid=54&frmView=ShowPost&PostID=3237
I would check the suction/return hose that is behind the battery first, you may have to clean any gunk out first to see if it is leaking or a little loose. Pressure wash it real good and reinstall the battery and run it till it warms up and then let it sit overnight and recheck for drips. If the suction line isn't leaking then it's the pump. Put the kit in it or buy a new one. Changing the oil and filter may make the problem seem to go away or get better but it will soon return. There are no case drain filters on this model.
 

gost

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Forgot to answer, no no leaks at all.
Today I replaced the oil, and tightend the bolts to the "Hydrostat", they were loose, so I guess much air could go in here. But as I tightend the bolt after running a test with new oil, the oil was full of air bubbles, so tighten the bolts made no change. I´ll try again tomorrow.
 

gost

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Today I replaced the oil, and tightend the bolts to the "Hydrostat", they were loose, so I guess much air could go in here. But as I tightend the bolt after running a test with new oil, the oil was full of air bubbles, so tighten the bolts made no change. I´ll try again tomorrow.
At least now no air is in the oil, but It´s still slow. I guess I have to replace the pump.
 

Tazza

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At least now no air is in the oil, but It´s still slow. I guess I have to replace the pump.
It may pay to get it checked by the dealer before you throw a new pump at it. They can check the pressure and flow to confirm its a bad pump. With so few hours it shouldn't be the pump!
 

gost

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It may pay to get it checked by the dealer before you throw a new pump at it. They can check the pressure and flow to confirm its a bad pump. With so few hours it shouldn't be the pump!
Talked with the dealer and they said it MUST be the pump, so I ordered one brand new for approx 1000$ (as the former owner pays the pump). I´ll get it on friday and replace the old this weekend - I´ll post the result here
 
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