Cat 301.8C slow boom and bucket

[Davidonmars]

Hey guys I have a cat 301.8C jsb00713. Problem I have is the boom and bucket slow down when hot but the stick and swing are still lightning fast. Anyone ever encounter this problem before? Also the right side track when sitting on the machine with blade forward is noticeably weaker then the other track. Any help would be greatly appreciated. Thanks

 

[TrevsCivil]

Regarding the track you Probably already checked this, but just in case. Have you tried taking out the floor mat and cleaning any dirt from around the pedal? My operator had this issue recently and that’s what the problem was.

 

[Davidonmars]

Regarding the track you Probably already checked this, but just in case. Have you tried taking out the floor mat and cleaning any dirt from around the pedal? My operator had this issue recently and that’s what the problem was.

First thing I checked, was hoping it would be something that simple.

 

[Kobe Steel]

Hi
the functions you have mentioned are all supplied from the same pump line. To isolate further without the use of flow and test gauge equipment, try swapping the 2 pump lines at the main pump or the control valve which ever is easier and see if the problem goes to the other track motor and the stick/arm function. See pic attached. This should give an indication if the main pump is the cause of this problem.
kind regards

 

[Davidonmars]

Hi
the functions you have mentioned are all supplied from the same pump line. To isolate further without the use of flow and test gauge equipment, try swapping the 2 pump lines at the main pump or the control valve which ever is easier and see if the problem goes to the other track motor and the stick/arm function. See pic attached. This should give an indication if the main pump is the cause of this problem.
kind regards

Thank you very much, I’ll swap the lines and report back.

 

[Davidonmars]

Hi
the functions you have mentioned are all supplied from the same pump line. To isolate further without the use of flow and test gauge equipment, try swapping the 2 pump lines at the main pump or the control valve which ever is easier and see if the problem goes to the other track motor and the stick/arm function. See pic attached. This should give an indication if the main pump is the cause of this problem.
kind regards

I wasn’t able to swap the lines between p1 and p2 as the lines were too short and I don’t have fittings but I did pressure test p1 and p2. P1 which is boom, bucket and right track is at about 2400 psi I believe specs right around 3000. P2 is 2950. I’m assuming it’s an issue in the pump? Any idea where to start? Or anywhere else to check pressure?

 

[Kobe Steel]

Before removing the pump try swapping the p1 and p2 main relief valves and carry out your tests again. If p1 functions are still low in pressure then it is most likely your pump at fault. See pdf attached.

 

[Davidonmars]

Before removing the pump try swapping the p1 and p2 main relief valves and carry out your tests again. If p1 functions are still low in pressure then it is most likely your pump at fault. See pdf attached.

Do I unthread the entire valve that’s threaded into the valve block? Also are those the correct location for the relief valves because the first diagram shows p1 and p2 going into the same location. Main relief p1 in the pdf is where the swing line goes.

 

[Davidonmars]

Before removing the pump try swapping the p1 and p2 main relief valves and carry out your tests again. If p1 functions are still low in pressure then it is most likely your pump at fault. See pdf attached.

Swapped the 2 pressure relief valves and no change

 

[Kobe Steel]

I see the difference you pointed out in the diagrams , I will check again and report back to you, it may be a mistake in the literature.

 

[Kobe Steel]

As you pointed out there is a mistake in the labeling for that valve bank literature. here is the testing and adjusting procedure, see attachment below. No change in swapping reliefs would bring you back to the pump as a possible fault.

 

[Davidonmars]

As you pointed out there is a mistake in the labeling for that valve bank literature. here is the testing and adjusting procedure, see attachment below. No change in swapping reliefs would bring you back to the pump as a possible fault.

I guess I can try the adjustment procedure to P1 first. I swapped the swing and p1 relief valves, any harm in that?

 

[Kobe Steel]

No not for testing there is no harm, the relief for the swing is 2570 psi and the main is 2980 psi so not enough of a pressure difference to cause any harm to the slew pump.

 

[Davidonmars]

No not for testing there is no harm, the relief for the swing is 2570 psi and the main is 2980 psi so not enough of a pressure difference to cause any harm to the slew pump.

Now that you mention 2570 I’m pretty sure it was reading that on p1 after I swapped the relief valve from the slew. The slew valve is still in p1

 

[Kobe Steel]

If it was a relief that was bypassing to much oil then even swapping the main relief with the swing relief should of made a big difference to the performance so its suggesting that it still may be the pump unfortunately.

 

[Davidonmars]

If it was a relief that was bypassing to much oil then even swapping the main relief with the swing relief should of made a big difference to the performance so its suggesting that it still may be the pump unfortunately.

I turned up the adjustment and it didn’t make a difference. I guess the next step is to take the pump off?

 

[Kobe Steel]

If you remove the pump and inspect yourself then let me know and I can point out the common issues to look for. The head cover for those pumps has a heavy coil spring that is loaded so the head will want to spring off on you when it is being removed.