Cat 303.5E Mini Excavator Won't Turn

[Altenbrauch]

I have a 2014 Cat 303.5E CR mini excavator with 1800 hours on it. The serial number is 3035ECRKY03004. I have an issue in which the tracks will barely turn after the hydraulic oil is warm; it turns fine when first started, but the longer you operate it the slower it gets. It has noticeably lower power than it used to, but it can still dig if you scrape. The tracks still go in forward and reverse, but they're not as strong as they used to be.

Some things I've noticed:

If you run it on low RPMs it won't turn at all, and there's a flushing or swirling sound. On high RPMs it will turn, but just barely, easiest way is to drive forward and turn a bit, repeatedly.

I went down and then up a steep bank and the tracks seemed to be working better immediately after, but digging power was reduced. When I went back over the bank it went back to the way it was before.

After using it for awhile the blade will start to slowly bleed down.

Hydraulic oil level seems fine, but is at the maximum fill line. I haven't pulled the filters yet. I'm guessing it may be a seal, but I'm still new to operating heavy equipment and would appreciate any help and advice.

 

[Snobdds]

Is there an echo in here?

I would get a pressure gage and plug it into one of your hydraulic lines to see what the pressure is at and if it's staying consistent while using the hydraulics.

Start there and see what you get.

 

[nyone]

I would also replace the hydraulic filter and look up to see if it has a suction screen.

Usualy hot fluid and low pressure/volume could mean a worn hydraulic pump...but I'm sure this machine has 3-4 pumps.

 

[crashz]

I've rented two of these, and both seemed to do that when tracking. Tracking straight, it had plenty of power. Turning was a chore. Had to be at full throttle.

Digging power was pretty strong though. Both machines had power enough to pick large pieces of concrete that could tip the machine.

What is the service history? Recent filter and fluid changes? 1800 hours is not a lot.

 

[ruffdog]

Is the fluid foaming the hotter it gets? Also, if you have a worn pump or drive motors, they will be less efficient as the fluid gets thinner.

 

[caplimilan]

This problem is really weird. This is why I am not going to buy a piece of heavy machinery. If something breaks, there aren't many mechanics who know what they are doing regarding this matter. I would rather rent it from mayxaydungmh.com or another company and make sure that everything is going to run smoothly. After all, I don't need an excavator every day and it's not worth it to buy it. Maybe one day I am going to get one and rent it as well in order to make more money. Who knows?

 

[oldnslo]

Do you have the service manual with a copy of the hydraulic schematic? If not that is a good place to start in providing information on potential problems.

1) Since you state it loses digging capabilities along with drive capabilities that some what eliminates the track drive motors.
2) The low RPM flushing - swirling sound points towards flow going somewhere through a leak path. Possibly system relief, a bad O-ring, etc.
3) Could be several other items which is why I said above to obtain a copy of the hydraulic schematic so that the diagnosing can be based on knowns vs guesses.

 

[Altenbrauch]

I think it's a worn swivel seal, but I ended up taking it to Cat for service because I needed it fixed and didn't want to spend time and money taking stabs at it. I'll let you know what the final diagnosis is.