Cat 307 excavator

[hotwire22]

I was digging out a pond with my 307 and the crowd function stuck with the controls in neutral position. No hands on the control and the machine was crowding out by itself. I pulled the valve body fo rthat circuit and there was a chunk of metal the size of pencil eraser in it. The local CAT dealer has it and says they have to take the entire hydraulic system apart and flush every line and clean all the pumps and hydraulic cylinders and motors. They said the last one they did cost $12,000. This is a machine that is one year out of warranty and has 2100 hours and has had CAT service its entire life. Needless to say I am royally hacked off. I am assuming the metal came from the crowd cylinder. Do the filters not stop any of this? There is a filter ahead of the main hydraulic pump and one on the return ahead of the sump. What is your opinion on us cleaning out the valve body, changing the fluid, fixing the cylinder and running it through its paces then repeating the entire process a couple of times to try to catch all the metal. I really dont want to drop $12,000 into a $50,000 machine no matter how little hours are on it. Also is this unusual for a Cat machine and at $1000 in parts that is 100 hours at $100 labor rate per hour. That sounds excessive to me. I really think I am getting hosed. Come on fellas give me some help here!

[Tommjr]

First Off, Where do you live?

Second, do you have time to fix yourself?

Hydraulic systems all function the same, no matter what machine there in.

I just did a Complete pump and lift arms on a Bobcat S250. (1073 Hrs)

It takes a little time, However, you can make sure that the work is done right.

I would look on EBay for a manual, or go directly to CAT and get a $150 manual.

I have an 05' Yanmar, and the system cannot be much different than your CAT. Pretty simple. (Don't mean to rub it in, but Yanmar had a Three year warranty on there machine when I bought it 18 months ago).

Hope everything goes well.

[hotwire22]

What all did you do to the machine and why did you have to replace arms on a new machine? What do we need to check and what is the best way to filter the metal out of the system?

[Tommjr]

The machine belonged to a friend of mine who had hid DAD pay, while HE lacked to do his maintenence.

On Bobcat wheeled machines, there are no holes cut in the bottom of the lift arm mounts so dirt can escape. Thus when the dirt fills up, everytime you bring the arms down, it compacts and then the lift arms eventually bend and need replacing.

Do you have the boom plumbed for attachments? If so, Get a Regular hydraulic hose with a coupler on one end and an open fitting for the other end.

Drain the hydraulic tank, and whatever is left, push out through your Aux. Hydraulics.

Fix your problem, then Fill system, switch filters then flush through Aux. Hydraulics again.

Do this flushing at least 5 times with all new fluid and filters every time.

Once the flush is done, be sure to switch filters every 15-20 hours for at leat 100 hrs.

[Squizzy246B]

Hotwire, you didn't say where you are but $12K is a lot of brass no matter where. However, its more a point of where did the piece of metal come from?..what is the source of the contamination?. This determines what work is required. A particulate analysis by the lab can tell you if the contam is bad. Any good hydraulic shop can flush the system for you.

I certainly wouldn't consider Cat off the hook depending on what the actual problem is. I also wouldn't recommend you do it yourself unless you have a very good understanding of the machine, the risk and a good workshop. I used to work for Cat and know of no major probs with the 307. Just remember, if you screw the hydraulics on a hydraulic excavator..you are left with a diesel powered anchor.

Tommjr; All Cat compacts have 3 year warranty...1 year full, 2nd two drivetrain.

[Tommjr]

Squizzy,

The whole point of the repair is to do it with a service manual.

If a guy can't follow the service manual, he shouldn't be operating heavy machinery.


Hotwire,

Don't let anyone tell you that you can't accomplish this. This machine's hydraulic system could fit on a work bench. We are not talking about a brand new 385C here. You are just replacing a cylinder, or maybe a pump or some other Stationary Item, Simple bolt out, Bolt in Items.

I custom made my own thumb for my Mini, because I didn't like the design of the Aftermarket one, most guys would't attempt to weld on there machines, these things are simple devices, trust your gut.

As for the boat anchor, Right now the machine is a boat anchor, so what gives?


I live in WI. Shoot me a P.M. and we'll chat.

[Ford LT-9000]

What do you expect its a Cat the poorest quality machine built :yup

Just joking :bouncegri

You can probably flush the hydraulic system yourself I can't see it costing that much. The first thing is clean out the hydraulic tank I doubt the metal come from there but you will have contaminated oil now.

You will have to tear into the machine and find all the major supply hoses to the valve banks and check them. The smaller lines you disconnect both ends and use compress air to blow out the lines.

There really isn't much you can do that chunk of metal must have broken off in the valves for the controls or out of the main pump itself.

You really only have one choice is change the oil in the hydaulic tanks and maybe start cracking the external lines to blow out the crap.

I do have a question has this machine ever had a rock breaker on it ?

[digger242j]

...and there was a chunk of metal the size of pencil eraser in it.

Just a couple general questions, and anyone with an opinion is invited to reply--if it was a chunk of metal, what are the chances that that one chunk is all the metal that was floating around loose in the system? What part of the machine is missing a chunk that big, but still operating normally?

Hotwire, was there any evidence of metal shavings or other contamination in the filter?

[Wulf]

Just a couple general questions, and anyone with an opinion is invited to reply--if it was a chunk of metal, what are the chances that that one chunk is all the metal that was floating around loose in the system? What part of the machine is missing a chunk that big, but still operating normally?

Hotwire, was there any evidence of metal shavings or other contamination in the filter?

It is quite possible that the piece of metal broke off inside the cylinder and got stuck in the spool. Your Cat dealer can only guarantee their work if they do a total disassembly and clean-up so they are protecting their reputation.
It sounds like the debris may be a piece of plunger, piston or head from the arm cylinder but you would need to look in the parts book or manual to see how it is constructed. If you can identify the piece, find where it came from and there are no other missing pieces then you maye be lucky, loop the circuit lines, change the oil and run a clean-up filter.
Why don't you post a picture of the piece of debris on the forum...

[GeoffD]

1. Grab some oil samples.
2. Cut down your spin on filters
3. Replace you spin on filters with "clean out " filters run for 10 hours, test oil again.
4. Then see where you are at.

Geoff

[Wulf]

Unless the debris is in particulate form your oil samples will not tell you anything. If the piece is as big as an eraser then other particles are likely to be pretty large too. If your drain plug has a magnetic insert - check that. Also looking inside the tank, inside the filter pleats and suction strainer would provide a better evaluation of system contamination.

[rolloffhill]

Well? One day of posting and haven't heard anything...what gives...what did you decide to do????

[farmerted44]

welcome to the site rolloffhill. i thought you might enjoy this.

[Grader4me]

[QUOTE=Tommjr]Squizzy,

The whole point of the repair is to do it with a service manual.

If a guy can't follow the service manual, he shouldn't be operating heavy machinery.


Wow:eek: I missed this one! I kind of disagree with this statement. Yes, you should be able to follow a service manual to do your maintenance properly, for example change oil, grease, fuel filters, air filter changes, minor repairs etc. I am the type of person that I can take things apart easily, but have more difficulty putting it back together! So probally I would suck trying to accomplish the above task no matter how simple you make it sound. Now because of that, would this mean I shouldn't be operating heavy equipment? Not on your life. Been doing it for 25 years.