Good evening, any mechanics out there? I just picked up a '95 CAT E70B nice machine until I went to dig with it, all fine for the first 5 minutes until the fluid warms up everything works but I loose power on the bringing the dirt out of the hole and then the bucket looses its power and with a load in the bucket it "bleeds off" all other functions are fine. Of course I can't get a mobile mechanic out for several days. I can let it cool down and go back to digging for another 5 minutes and loose scoop power. I have operated and owned iron for most my adult life and never had this issue. Any Ideas? Hoping something simple like an electrical switch, and not a pump or valve. Thanks in advance for any suggestions, if I had a tester I could test pressures but I don't thus waiting for CAT to get a mechanic out.
How many hours on the machine, my first instinct is that warm oil flows threw large clearances faster than cold. maybe it's worn out?
The machine has 5000 hours. Just took the bucket cylinder off and took it to Northern Fluid Power guessing it may be the packing O rings dura-seal they took it apart and all looks good no internal or external leakage, small score on rod they are going buff it out and repack it replacing with fresh hydraulic oil, reinstall it and and see what happens. Next we will have a pressure test and check the valve, everything runs too strong except the bucket curl to be the pump but who knows. If anyone has any other suggestions please let me know I am sitting on a job with a mystery problem.
maybe a valve out of adjustment, hard to say did the problem start suddenly or gradual?
Is the bucket drifting with your hand off the control?
Yes when in neutral it bleeds / drifts off
It could be in the cylinder. Hopefully you'll get lucky there. I would have looked at the $4 orings on the port relief valves before taking the cylinder off. You can swap port (line) reliefs between functions temporarily if the part numbers are the same. Really I'd try and get a decent tech out there if it's not the cylinder. You can spend a lot of money fixing things that aren't broke and then find out it was a bolt loose or a broken centering spring or something really inexpensive parts wise.
Thanks! we are trying our best to get a tech out to the machine but as you know being from Canada we don't have Summer we have Construction season and the good techs are a month out. We are hoping that there may have been something in the cylinder and the fresh packing kit will resolve the issue, if it were our machine I assure you everything would have been maintained but we just bought this with the assurance all was in working order since it was on asphalt and no way to dig and that would have been the only way to have known this issue. Assuming it is a relief valve hopefully the CAT dealer will have it in stock (good luck with that one, and if they do they will want 6 times the cost elsewhere in the lower 48.) I will keep you posted once the bucket cylinder is back on there is still that remote chance that it may be that, keep fingers crossed, hope and prayers, we need to get this dig done!
Ok, just an update, took the E70B to NC Cat they pressure tested and one side of the main hydraulic pump is great the other side low pressure with the mechanic thinking out side the box he apparently jumped an actuator and tested again and got the pressure to operate the bucket under load. Still waiting to see if this cures the problem but keeping fingers crossed and hopes high that we can get the part out of Anchorage and get her back on the job! Thanks for everyone's help!
so there was nothing wrong with the cylinder? same symptom after reseal? Still drifting? Look at the line reliefs. Swap them with the stick or boom line relief for quick test. Drift is not caused by anything in the pump. Drift is between the dcv spool and the hose to the cylinder if cyl has been eliminated. Pressure testing is sorta farting in the wind for a drift issue. You can't make pressure if an O ring is off the line relief. Don't blame a $10,000 pump for a $4 oring. You may have an unrelated issue though - those E70B pumps have a shuttle valve in the pump that likes to leak one way and make one half of the machine weak. Maybe their tech is just routinely looking for that.
Yeah the pump won't cause cylinder drift. I would bet on a bad line relief. Easy to swap and test before you spend a bunch more money.
Latest update .... well $1700.00 later for troubleshooting the issue the mechanic pulled the relief valve cleaned it and put it back in and it finished the foundation dig no problem. So far so good! now I am replacing the bottom rollers and no where can I find the torque specs for the bolts. Sooooo...... one of you guys that might know can you get back to me ASAP since just about ready buckle up one side. doesn't help it is Saturday and NC CAT is not open to have them look it up for me. Thanks again!!! Mobilteck Alaska could use a good tech
Are they M12 bolts..? At least that's what the Parts Manual shows. If so, 75 +/- 15 ft.lbs.
thanks so much Thanks so Much one side done on to the other!!!!
Mobiltech and all, Well CAT finally got new relief valves so we can replace the ones that were weak, now my question not wanting to give CAT a bunch more $$$ to drop the new relief valves in the mechanic said they are simple just drop and screw in. That sounds all good and well but apparently CAT has a special tool or trick to get on the valve to remove it since there is very little room between them. First thought was a crows foot wrench or long thin wall socket (which would work slick, but unable to find one) any suggestions, tips or tricks? Anyone with a service manual that can look up if there is a special procedure or tool referenced. Thanks again all