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Cat 951c hydraulic pump problem

Cat 951c hydraulic pump problem

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uisum
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Hello guys ,
I have a hydraulic problem with a 951c loader. serial 69h3944.
Hydraulic fluid looks like white foam. The hydraulic pump makes a loud noise. When used under pressure with a loaded bucket, it struggles to almost lift and the pump makes a loud noise. The noise occurs under both lift and bucket load.
What to check?
Thank you
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Wed, Jun 23, 2021 7:35 PM
Deas Plant.
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Hi, uisum.
I'm gonna stick my neck out here and suggest that your pump may be beyond its use-by date and it is by-passing inside the pump.

Just my 0.02.

You have a wonderful day. Best wishes. Deas Plant.

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Wed, Jun 23, 2021 10:17 PM
uisum
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Hello
can I remove the 4 bolts that are behind the pump to give them a look?
Thanks you
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Wed, Jun 23, 2021 10:26 PM
Old Magnet
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Reply to uisum:
Hello
can I remove the 4 bolts that are behind the pump to give them a look?
Thanks you
Foaming oil usually means the system is picking up air. Check for suction line leaks or leaking seals.
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Wed, Jun 23, 2021 11:37 PM
uisum
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Reply to Old Magnet:
Foaming oil usually means the system is picking up air. Check for suction line leaks or leaking seals.
Hello old ...
where is the suction line located?
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Wed, Jun 23, 2021 11:47 PM
Deas Plant.
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Reply to uisum:
Hello old ...
where is the suction line located?
Hi, uisum.
It will be a fairly big line running from low down on the tank to the pump. Taking the floor plates out may help in locating it.

If the fault does lie with suction line, there MAY be some signs of oil leakage at the site as the system is normally pressurized when working.

Just my 0.02.

You have a wonderful day. Best wishes. Deas Plant.

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Thu, Jun 24, 2021 12:11 AM
uisum
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Reply to Deas Plant.:
Hi, uisum.
It will be a fairly big line running from low down on the tank to the pump. Taking the floor plates out may help in locating it.

If the fault does lie with suction line, there MAY be some signs of oil leakage at the site as the system is normally pressurized when working.

Just my 0.02.
Hello
no kind of loss there.
l oil is like milk. I'm not sure it's foaming.
I took it out and put it in the bins. Could that be the problem of loud noise during exertion?
The hydraulics work, but if you strain for example: bucket on the ground to lift the loader you will hear a loud screech in the pump.
when I load the bucket full of earth and lift I hear a loud noise ..
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Thu, Jun 24, 2021 12:47 AM
Old Magnet
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Reply to uisum:
Hello
no kind of loss there.
l oil is like milk. I'm not sure it's foaming.
I took it out and put it in the bins. Could that be the problem of loud noise during exertion?
The hydraulics work, but if you strain for example: bucket on the ground to lift the loader you will hear a loud screech in the pump.
when I load the bucket full of earth and lift I hear a loud noise ..
Attachment
Attachment
Attachment
Attachment
Water in the oil will cause it to go white as well as air leaks. The suction line has three rubber hose couplings and clamp connections which are usual suspects for leakage. Leaking o-rings at flange connections could also be a problem.
Pump cavitation due to air leakage could be the source of noise from the pump.
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Thu, Jun 24, 2021 1:28 AM
uisum
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Reply to Old Magnet:
Water in the oil will cause it to go white as well as air leaks. The suction line has three rubber hose couplings and clamp connections which are usual suspects for leakage. Leaking o-rings at flange connections could also be a problem.
Pump cavitation due to air leakage could be the source of noise from the pump.
[quote="Old Magnet" post=229281"]Water in the oil will cause it to go white as well as air leaks. The suction line has three rubber hose couplings and clamp connections which are usual suspects for leakage. Leaking o-rings at flange connections could also be a problem.
Pump cavitation due to air leakage could be the source of noise from the pump.


 [/quote]
I didn't quite understand where these suction lines are located.
You say under the hydraulic oil tank? I don't see any leaks here 'it's all dry.
Is it possible that the milky oil creates loud noises in the pump and loss of power?
When I unscrewed the 4 bolts of the pump I felt some air...
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Thu, Jun 24, 2021 1:45 AM
Deas Plant.
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Location: Currently - DowNunda.
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Reply to uisum:
[quote="Old Magnet" post=229281"]Water in the oil will cause it to go white as well as air leaks. The suction line has three rubber hose couplings and clamp connections which are usual suspects for leakage. Leaking o-rings at flange connections could also be a problem.
Pump cavitation due to air leakage could be the source of noise from the pump.


 [/quote]
I didn't quite understand where these suction lines are located.
You say under the hydraulic oil tank? I don't see any leaks here 'it's all dry.
Is it possible that the milky oil creates loud noises in the pump and loss of power?
When I unscrewed the 4 bolts of the pump I felt some air...
Hi, uisum.
The suction line to the hydraulic pump will be a bigger, low pressure line, not heavy construction like the high pressure hoses. It has been a LONG time since I had anything to do with these old girls but I think it starts either under the hydraulic tank or on the inboard side near the bottom and will lead to the hydraulic pump, hence the suggestion to remove the floor plates.

'Kwestyun': How long has it been making these noises and been low on hydraulic power?

'Nuther 'kwestyun': Has it been getting steadily worse or did it suddenly start doing these things?

Just my 0.02.

You have a wonderful day. Best wishes. Deas Plant.

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Thu, Jun 24, 2021 3:21 AM
uisum
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Reply to Deas Plant.:
Hi, uisum.
The suction line to the hydraulic pump will be a bigger, low pressure line, not heavy construction like the high pressure hoses. It has been a LONG time since I had anything to do with these old girls but I think it starts either under the hydraulic tank or on the inboard side near the bottom and will lead to the hydraulic pump, hence the suggestion to remove the floor plates.

'Kwestyun': How long has it been making these noises and been low on hydraulic power?

'Nuther 'kwestyun': Has it been getting steadily worse or did it suddenly start doing these things?

Just my 0.02.
[quote="Deas Plant." post=229287"]Hi, uisum.
The suction line to the hydraulic pump will be a bigger, low pressure line, not heavy construction like the high pressure hoses. It has been a LONG time since I had anything to do with these old girls but I think it starts either under the hydraulic tank or on the inboard side near the bottom and will lead to the hydraulic pump, hence the suggestion to remove the floor plates.

'Kwestyun': How long has it been making these noises and been low on hydraulic power?

'Nuther 'kwestyun': Has it been getting steadily worse or did it suddenly start doing these things?

Just my 0.02.[/quote]
Hi .. The crawler loader had stood still for maybe 10 years. I bought it like this.
Could it be the oil that looks like milk? who creates all this noise?
hydraulics work but the noise is bad, and the power is not what it should
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Thu, Jun 24, 2021 3:37 AM
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