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Bobcat  > Compact Track Loaders  > T300 with no real lifting power  
 
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 Author Thread: T300 with no real lifting power
gtstang462002 is not online. Last active: 1/15/2013 5:58:57 PM gtstang462002
Joined: 27 Mar 2010
Total Posts: 77
 
T300 with no real lifting power
Posted: 03/27/2010 07:30 PM
I recently acquired a T300 for no money out of my pocket that has 3500 hours on it. The story that is told to me is that the machine had an engine put into it by the mechanic that worked for the company at the time and has since had no real lifting ability. Playing with the auxillery hydraulics and holding the control switch to the left seems to give if better pressures. The Bobcat dealer seems to think that the control valve is cracked internally and allowing pressure to bypass internally. Also the park brake doesn't hold the machine. Tbe dealer is recommending both drive motors. I am seeing a couple posts on here referencing that the brakes can be rebuilt. My thoughts are that the 2 issues are probably related somehow. I am waiting on a service manual to arrive from ebay, but in the meantime throw it out there to see if anyone has any prior experience with these issues. I am a master ASE certified auto tech, but have little experience with Bobcats in general.

Bobcat T300, Possible 751 on the way
Tazza is not online. Last active: 10/30/2014 3:08:13 PM Tazza
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Re: T300 with no real lifting power
Posted: 03/28/2010 07:32 PM

It could be as simple as an aux hydraulic solenoid being stuck open. This will cause hydraulic pressure to be built up in your aux circuit reducing what you can lift. Can you get a hose made up to loop between the quick couples on the front?

Just a thought.


Bobcat 763 burntSadbut i'm working on it!, 04 S150 with air and a smooshed cab, S250 turbo.
gtstang462002 is not online. Last active: 1/15/2013 5:58:57 PM gtstang462002
Joined: 27 Mar 2010
Total Posts: 77
 
Re: T300 with no real lifting power
Posted: 03/29/2010 12:55 PM
I don't have a loopback hose available. And the local hydraulic shop wants a fortune to make one up. The dealer has already replaced the solenoid and stem on the control valve for the auxilery hydraulics. Here is the diagnostics that they typed up word for word: " COULDN'T ACCESS CONTROLLER. FOUND BAD UNSWITCHED FUSE. REPLACED AND UPDATED AND PULLED CODES. CHECK LIFT AND TILT FUNCTIONS. AUX. FUNCTIONS ARE STUCK ON. HANDLE, CONTROLLER AND WIRING OK. ONE AUX STEM AND SOLENOID, REMOVED CONTROL PANEL TO ACCESS CONTROL VALVE. SOMEONE INSTLLED REAR AUZ. SPOOLL SPRING AND HARDWARE BACKWARDS CORRECTED AND INSTALLED. AUX FUNCTIONS STILL ON. RECOM. REPLACING CONTROL VALVE UPON SPEAKING TO MECHANIC AND CUSTOMER WE DECIDED TO TEST DRIVE MOTORS AND RIGHT SIDE FAILED . CUSTOMER HAS DECIDED NOT TO PROCEED FORWARD. CUSTOMER PICK UP AS IS." This is with typo's and full grammatical errors to the T off of the the final bill to the company that I got this machine from. For all of that the customer got charged $1024.45. Aside from the brakes in the drive motors not working I can't find anything wrong with the motors. Based on this information I am thinking that it will be worthwhile to take the entire Aux circuit apart and making sure that the springs are there on both sides. Prior to me getting this machine I rebuilt the detent system for the lift arms due to it being stuck in float mode. After doing that everything moved but had no power. After getting it back from the dealer you now have to turn the Aux hydraulics on and hold the right thumb switch to the left to move the lift and tilt. Thanks for taking the time to assist me with this issue, Bobby

Bobcat T300, Possible 751 on the way
Tazza is not online. Last active: 10/30/2014 3:08:13 PM Tazza
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Re: T300 with no real lifting power
Posted: 03/29/2010 01:53 PM

I see they confirm the aux is stuck on too. I don't know exactly how its controlled in the valve its self, but i assume its done with a spool that is moved from side to side with oil from the coil and stem setup. Its always possible a spring is broken or the spool is sticky. I'd assume a spring as you mentioned you can operate the aux hydraulics in one way to give you back lift and tilt power.

I have been lucky enough to not have an issue like this, only coils and stems. As a quick test, try swapping stems from side to side, see if the fault can still be cleared with moving the thumb switch in the same direction. Keep the coils in the same place, only move the stems.

This will just rule out a sticky stem, you never know, they may have over looked it.

If its still on the same side, i'd pull the spool out of the control valve, see what you can find.

 


Bobcat 763 burntSadbut i'm working on it!, 04 S150 with air and a smooshed cab, S250 turbo.
gtstang462002 is not online. Last active: 1/15/2013 5:58:57 PM gtstang462002
Joined: 27 Mar 2010
Total Posts: 77
 
Re: T300 with no real lifting power
Posted: 03/30/2010 01:22 PM
I will give this a run once this rain settles down. Probably tomorrow afternoon I will be able to get to it. Do you know of a place that I can get the cab springs/shocks cheap? As of right now I lift the cab with a chain up over the top hooked to my truck, lol.

Bobcat T300, Possible 751 on the way
Tazza is not online. Last active: 10/30/2014 3:08:13 PM Tazza
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Re: T300 with no real lifting power
Posted: 03/30/2010 01:54 PM

Sadly i don't know anyone in the US. Try places that do automotive gas struts for boots. My dad found a place that will gas a strut to the pressure i want. He uses an old one and measures its force, then charges the new one to suit (i had one good and one bad one). They are around 100kg!!

Does it have the sruts on it? as the left side should have a tube to lock the cab up, it can't fall on you then. Its a tube that goes around the gas strut with a lever to release it.


Bobcat 763 burntSadbut i'm working on it!, 04 S150 with air and a smooshed cab, S250 turbo.
gtstang462002 is not online. Last active: 1/15/2013 5:58:57 PM gtstang462002
Joined: 27 Mar 2010
Total Posts: 77
 
Re: T300 with no real lifting power
Posted: 03/30/2010 02:00 PM
Nope, all the pins and clips are there, just no struts. I have not priced them out from bobcat, little afraid of the price, to be honest with ya.

Bobcat T300, Possible 751 on the way
Tazza is not online. Last active: 10/30/2014 3:08:13 PM Tazza
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Re: T300 with no real lifting power
Posted: 03/30/2010 07:17 PM
This is very true. I think the price i got for the tube to lock the cab up was just insane, but that was an australian dealer, so the price was at least double yours.

Bobcat 763 burntSadbut i'm working on it!, 04 S150 with air and a smooshed cab, S250 turbo.
Fishfiles is not online. Last active: 2/23/2014 3:44:14 AM Fishfiles
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Re: T300 with no real lifting power
Posted: 03/31/2010 02:15 AM

Worst case senerio is what you may be looking at , the both problems can go together as you think ,   I  seen it quite a few times now on the T300 and 250 where it is total burn up of the hydraulic system caused by the operator continue to run the machine with brake problems and the hydraulic system is like a blender and grinds up all the fragments , which over loads the case drain filters and makes it by and  get stuck in reliefs and aux coil stem valves which could be why your aux is  sticking on ,  the trash will take  out the gear/charge pump and the sunstrand , I seen one these jobs last week that cost $19,000 at the dealer  to change both travel motors , the sunstrand , gear/charge pump , flush the system and clean all the reliefs , and stem valves , if the machine is a little older and this is the case then it is really not worth putting that amount of  money into it -------------I would hook a hose to the aux quick couple and pump a gallon of oil into a clean bucket and look for the golden sheen in the oil , if you let the oil sit you won't see it , it needs to be stirred up , if it's funky an oil analysis would be helpful ,  I'd also check whats in the hydraulic filter and case drains , the dealer that worked on should have clean the case drains if they evaluated the brakes where bad so you might not find alot there now , I would bet if you set your display to vitals and monitor the charge pressure at start up , then seat bar down and push to operate button depressed you will see the charge pressure fall off and not recover , and if you did a pressure test you would find the pressure way down  ---------------just letting you know the worst case so you don't start putting money and time into it , pecking around and not getting to the real problem and it become a money pit that never ends , sometimes a deal thats too good to be true, really  isn't

gtstang462002 is not online. Last active: 1/15/2013 5:58:57 PM gtstang462002
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Re: T300 with no real lifting power
Posted: 03/31/2010 04:16 AM
Prior to my aquisition of this machine, I have had the control valve out previously due to the detent system being suck in float mode. While I had it out I replaced the green seals on the lift and tilt circuits in the valve. All of the fluid that came out of the valve itself was completely clean(no debris of any type). The hydrualid pressure in the vitals floats around 435-485 regaurdless of engine speed and press to operate. I understand what you are saying about it becoming a money pit, but I don't have a dime in this thing as of now and even to buy a used one that is supposedly in good shape I am looking at 20K for a machine with heat and a/c. At least if I rebuild the hydro system on this one I will know that it is good to go for myself and not have to worry about what happened in it's previous life. I am still waiting on my manual to get here(if it is spiral bound I will scan it and contribute it to the manual collection on this site) where is the system pressure tested at?

Bobcat T300, Possible 751 on the way
gtstang462002 is not online. Last active: 1/15/2013 5:58:57 PM gtstang462002
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Re: T300 with no real lifting power
Posted: 03/31/2010 04:12 PM
So I swapped the stems today and wouldn't you know it, I had to flip the switch to the right instead of the left to get my lift and tilt functions back. With the stems in the current position the lift and tilt kinda work without hitting the Aux switch. We will find out on monday if it is as simple as a stem. Fishfiles, The hydro fluid is beautifully clean, I have not taken the brakes apart yet though. Working one issue at a time.

Bobcat T300, Possible 751 on the way
Tazza is not online. Last active: 10/30/2014 3:08:13 PM Tazza
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Re: T300 with no real lifting power
Posted: 03/31/2010 04:46 PM

You do know the stems can be fixed if there is trash in it? i have even repaired a bent stem.

They can be pulled apart, cleaned and re-assembled.

I did this to my S150 that had a sticky stem. Also my S250 had a bent stem. I straightened it as much as i could (slight bend), but the plunger was binding up slightly. I took a very light skim out of the inside of the tube with a drill bit in the lathe, works like a charm now. I had nothing to lose, i'd just have to buy a new stem if it didn't work.


Bobcat 763 burntSadbut i'm working on it!, 04 S150 with air and a smooshed cab, S250 turbo.
gtstang462002 is not online. Last active: 1/15/2013 5:58:57 PM gtstang462002
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Re: T300 with no real lifting power
Posted: 03/31/2010 04:53 PM
I was not aware of that. Now I have no idea which one is which so I guess I will clean them both. It is only $80 so it isn't that bad if I can't get it right. Better than the $2300 for a new control valve that the dealer is suggesting.

Bobcat T300, Possible 751 on the way
Tazza is not online. Last active: 10/30/2014 3:08:13 PM Tazza
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Re: T300 with no real lifting power
Posted: 03/31/2010 07:14 PM

Good point.

A good test is to turn the ignition on, press the aux hydraulic button, lift the cab and operate the thumb switch. Listen and feel which stem is buzzing. If it does not buzz, thats the bad one.

To disassemble, remove the stem, Hold the end with the O rings in a vice using two pieces of alloy as soft jaws, turn the hex with a spanner to seperate it. It will not be too tight. Pull the parts out of both ends and clean with solvent and compressed air. Re-assemble and you should be good to go.

People make you think they are complicated, they really aren't. I  have done two so far with out any issues.


Bobcat 763 burntSadbut i'm working on it!, 04 S150 with air and a smooshed cab, S250 turbo.
Fishfiles is not online. Last active: 2/23/2014 3:44:14 AM Fishfiles
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Re: T300 with no real lifting power
Posted: 04/01/2010 03:41 AM
You might get lucky on the stem stuck , I  would do like Tazza says , and  I would try to find why it stuck , a flake of trash ? ------alot of how I felt about what could be going on had to do with the machine having come out a dealers shop , I was giving them too much credit  and  can see now that they may have been not that good at what they do to have missed something so simple , can I ask who was the dealer and what state and city - as far as the oil being clean  I would think that they changed the oil , filter and drains -- your charge pressure sounds good  ---the brake is pretty easy to rebuild , and easily tested  ----lets hope once the stem is replaced or repaired that your lifting power comes back
gtstang462002 is not online. Last active: 1/15/2013 5:58:57 PM gtstang462002
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Total Posts: 77
 
Re: T300 with no real lifting power
Posted: 04/01/2010 05:58 AM
Cleaning the stem fixed the sticking aux hydraulics, still doesn't have the lifting power. I am going to borrow a pressure gauge from a friend this afternoon to see where the pressure is at. From what I understand the previous mechanic for the company messed with the relief valve and would not surprise me to find that it is out of spec. The only thing that I found in the stem was a little bit of what looked like tarnish. Otherwise it looked ok. I cleaned with out with brake clean and air and reassembled. The Aux works like it should now, thanks. I will keep this thread updated with what I find. Hope that it helps that next person that comes along with similar issues.

Bobcat T300, Possible 751 on the way
gtstang462002 is not online. Last active: 1/15/2013 5:58:57 PM gtstang462002
Joined: 27 Mar 2010
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Re: T300 with no real lifting power
Posted: 04/02/2010 02:58 PM
So, rigged up a pressure gauge to the aux hydraulics and threw pressure to the line to find that it only had 1200psi at idle as well as full throttle. I shut it down turned the screw in on the pressure relief and retested. With 2 turns that brought me up to 2300psi. 3 more times of starting it, checking pressure it was sitting dead nuts on 3450psi which is the high side of the spec in the manual. This thing is now digging and lifting like there is no tomorrow. Now to rebuild the brakes, a set of idlers(front and rear, both sides) sprockets and some tracks and this thing is in business to make some money.

Bobcat T300, Possible 751 on the way
Tazza is not online. Last active: 10/30/2014 3:08:13 PM Tazza
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Re: T300 with no real lifting power
Posted: 04/02/2010 04:40 PM

Should the pressure set to about 3,000 PSI? I think thats about the go for all modern machines, i'd avoid going too high, You will get more lifing power, but you run the risk of blowing hoses.

Glad its running a LOT better than it was. Just gotta get the brakes fixed, and you're set!


Bobcat 763 burntSadbut i'm working on it!, 04 S150 with air and a smooshed cab, S250 turbo.
gtstang462002 is not online. Last active: 1/15/2013 5:58:57 PM gtstang462002
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Re: T300 with no real lifting power
Posted: 04/02/2010 05:47 PM
Manual says 3350-3450. That is what I set it by.

Bobcat T300, Possible 751 on the way
Tazza is not online. Last active: 10/30/2014 3:08:13 PM Tazza
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Re: T300 with no real lifting power
Posted: 04/03/2010 05:54 AM

I never knew thay ran that high, good to know though.


Bobcat 763 burntSadbut i'm working on it!, 04 S150 with air and a smooshed cab, S250 turbo.
gtstang462002 is not online. Last active: 1/15/2013 5:58:57 PM gtstang462002
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Re: T300 with no real lifting power
Posted: 04/03/2010 05:56 AM
I am working on scanning the service manual into a PDF to contribute it to the Old Machinists library.

Bobcat T300, Possible 751 on the way
Tazza is not online. Last active: 10/30/2014 3:08:13 PM Tazza
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Re: T300 with no real lifting power
Posted: 04/03/2010 06:11 AM
Excellent, looking forward to grabbing a copySmiley

Bobcat 763 burntSadbut i'm working on it!, 04 S150 with air and a smooshed cab, S250 turbo.
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