Hydraulic Pump Noise? How to diagnos? TC-21 New Holland

[Ken M]

I have started to get a very sharp "ping" like noise around engine. Not related to engine rpm. Sounds metalic like a ball bearing bouncing around. Not constant. A random noise. Does not do it with any particular front bucket movement. As best I can determine it may be in (or near) the hydraulic pump. I don't have any experience with these pumps so I don't know how they might fail.

Is there anything else near the pump that might cause this noise? A 1.0L Shibura diesel, 1400 hours. I wonder about removing/ examining inside of filter for metal chips. Would this tell me anything?

Suggestions please. Thanks. ---KenA

 

[TractorTech]

If the sound doesn't change with rpm or hydraulic load, probably not the pump

 

[rScotty]

A hydraulic pump can "cavitate" and make a metallic rattling or pinging noise at low RPM if the hydraulic fluid is way low or has too much air in it. However, that rattle turns into a constant whine at higher RPM.
Since yours doesn't change with RPM and is random with load then it doesn't sound like it is the pump.

The hydraulic pump is a set of gears driven by a gear inside the engine. It's usually very quiet. Even when a pump is old, leaky, and worn out, they still don't tend to make much noise unless it whines from low fluid/air in fluid. And the noise they make usually changes with RPM.

Some use a mechanic's stethoscope or listen to the handle of a long screwdriver to help pinpoint noises....I've not had great luck using either diagnostically, but it sure is interesting how much more you hear that way.

Two things I would do. One is change the oil filter and take the old one apart to look for metal. You can probably do that without changing the oil...though that might be a good thing to do as well.

And the other thing is to check and see if your tractor is one that has a cleanable wire hydraulic "crud" filter in the transmission sump. Those can clog up and cause erratic fluid starvation problems.

 

[Ken M]

A hydraulic pump can "cavitate" and make a metallic rattling or pinging noise at low RPM if the hydraulic fluid is way low or has too much air in it. However, that rattle turns into a constant whine at higher RPM.
Since yours doesn't change with RPM and is random with load then it doesn't sound like it is the pump.

The hydraulic pump is a set of gears driven by a gear inside the engine. It's usually very quiet. Even when a pump is old, leaky, and worn out, they still don't tend to make much noise unless it whines from low fluid/air in fluid. And the noise they make usually changes with RPM.

Some use a mechanic's stethoscope or listen to the handle of a long screwdriver to help pinpoint noises....I've not had great luck using either diagnostically, but it sure is interesting how much more you hear that way.

Two things I would do. One is change the oil filter and take the old one apart to look for metal. You can probably do that without changing the oil...though that might be a good thing to do as well.

And the other thing is to check and see if your tractor is one that has a cleanable wire hydraulic "crud" filter in the transmission sump. Those can clog up and cause erratic fluid starvation problems.

Thank you for this information. I don't run the engine at high rpm so I will try that and listen. I did use a stethoscope and a long tube but it does help me isolate the noise. I will take off filter and tear apart. The fluid was changed two years ago and appears very clear but as you mentioned I will probably replace it also. No crud filter/screen that I know of and I had the tranny apart years ago for a broken gear.

One more thought... Is it possible I have a piece of metal floating around in the oil pan that gets picked and hits a pickup screen? Never had a reason to have the pan off so I don't know that is put together. Hummm... Maybe a strong magnet on the pan would capture it? This would be easy/fast to try. Thanks again.