Bobcat 323 - weird problem with weak boom.

[piotr1703]

Hello everyone. I have a Bobcat 323 excavator. The problem is that the boom is weak when moving up or down and it cannot reach the specified pressure value. However, when I operate another function at the same time, the boom immediately works normally and the pressure rises.


Other functions like the bucket, arm, and auxiliary hydraulics work fine. The measured pressure reaches the specified value even at idle speed, and I can hear the engine RPM drop when the function reaches full load, but this does not happen with the boom.


I noticed a similar situation with the drive motors. When I operate one drive motor and at the same time move, for example, the bucket, the drive motor immediately goes faster. The same thing happens with both drive motors.

I swapped the boom cylinder control valve section in the valve block with the travel motor section (the closest one). It didn’t change anything.


I also swapped the pump outlet lines to the manifold. Same result.


I disassembled the entire manifold/valve block and didn’t find anything unusual. The O-rings were replaced.


The pump is the only thing left.


Any ideas?

 

[brdgbldr]

Hello everyone. I have a Bobcat 323 excavator. The problem is that the boom is weak when moving up or down and it cannot reach the specified pressure value. However, when I operate another function at the same time, the boom immediately works normally and the pressure rises.


Other functions like the bucket, arm, and auxiliary hydraulics work fine. The measured pressure reaches the specified value even at idle speed, and I can hear the engine RPM drop when the function reaches full load, but this does not happen with the boom.


I noticed a similar situation with the drive motors. When I operate one drive motor and at the same time move, for example, the bucket, the drive motor immediately goes faster. The same thing happens with both drive motors.

I swapped the boom cylinder control valve section in the valve block with the travel motor section (the closest one). It didn’t change anything.


I also swapped the pump outlet lines to the manifold. Same result.


I disassembled the entire manifold/valve block and didn’t find anything unusual. The O-rings were replaced.


The pump is the only thing left.


Any ideas?

Check this video and see if your problem is similar:

 

[piotr1703]

Saw that video already. My issue is different and there is no ls system od 323 model. It's look like there is transition between pump sections and while other move is engaged the oil flow is closed to build up valve and In that case pressure rise up.

 

[Sapientoni]

It's weird that removing this designed in part fixed a problem. I'm curious if the problem did NOT exist during prior operation of the machine. If this orifice limiter was working properly before, was there an obstruction? Not being aware of this flow limiting orifice, I would have suspected basic air in the system because the fluid coming in had to compress the air and until the air pressure was sufficient to move the boom, it was just moving slowly as pressure built. The faster down movement reinforced the "air in system" possibility. Experience put that tech right onto the problem. KUDOS!

 

[piotr1703]

What are you talking about?
There is no LS (Load Sensing) system in the I 323 model, and there never has been one.