Anybody want to help me with my E70B. I bought this locally from a guy that didn't want to mess with it. What's wrong? It seems to have more than half the hydraulics working. The right track, the boom, the stick and the bucket somewhat operate. Barely. Sometimes the boom, stick and bucket have enough strength to lift the machine up. The right track moves a little but can't actually move the machine. The left track and swing do nothing. The swing sounds like it's trying to do something; nothing moves, but I can hear the pump labor like flow is being sent to the swing but nothing happens. The left track does nothing, no labor, no movement. What I've tried From what I can tell the oil is pretty clean of metal. I did drain and clean the tank, replace the hydraulic filter, inspected the giant piping from the tank to the pump. Then put like 20 or 25 gallons in the system. Whatever it took to refill it. I swapped the 2 hoses coming off the rear and front pumps and nothing changes. Exact same behavior. I have some hydraulic test gauges. I capped the rear pump outlet and put a gauge on the front pump. Started the engine and the pressure jumped to around 1200 psi and immediately dropped to maybe 100-200 psi. I swapped the setup; capped the front pump and tested the rear pump, it never had any pressure. I also have a CAT test port quick connect and tapped into the front and rear pump ports. Each time I got very little pressure. Once in a while if I would move a cylinder (the boom) the pressure would jump to 1200psi and immediately fall off. The boom would keep moving though. I could lift the machine and still show little pressure on the gauge. I also used the quick connect to test the pilot pump and it seemed to be running at 150-200 psi. Any advice would be appreciated. Thanks Robert
My first suggestion would be to get hold of a service manual that will contain a section explaining how the hydraulic system works. Until you understand that it would be extremely difficult to diagnose it. Post a machine Serial Number so that the appropriate manual can be identified.
Got a little free time to work on this machine last week. The SN is 7YF01209. I bought a service manual some time back. It's not easy to read as the print is real grainy. I'd like to get something better actually. While screwing around I was able to get the control box working by putting a fuse in the panel for that circuit. Previous owner removed that fuse, probably because when I plugged it in the buzzer came on and wouldn't go off. The LEDs gave me a code that pointed to the Proportional valve solenoid. So I'm just going through that trouble shooting. The LEDs lit up were L1, L4, L6 would flash, L7 and L9.
Sounds like a broken pump. You say you capped off the pump outlets one at time and that is a problem. Sounds like you dead headed a pump which when things are working normally can stop the engine from turning when trying to start it or physically breaking the pump. It sounds like a damaged barrel and valve plate on one pump. How many hours are on this machine?
Your excavator is a Japanese grey import. For an English service manual search for Caterpillar Publication reference SENR4570. That manual is for a “World” model of E70B with a 5TGxxxxx Serial Number but it will also work for your machine. See this link which is a genuine OEM Manual. CAT CATERPILLAR E70B EXCAVATOR SERVICE SHOP REPAIR MANUAL BOOK S/N 5TG00001-UP | eBay CAT CATERPILLAR E70B EXCAVATOR SERVICE SHOP REPAIR MANUAL BOOK S/N 5TG00001-UP | Business, Office & Industrial, Agriculture/Farming, Equipment Parts & Accessories | eBay! www.ebay.ie
Shows about 4000 hrs, I'm not sure how accurate that is. The 2 pumps are combined into one housing. From what I can tell reading thru the manual they share a swash plate. It appears the swash plate is adjustable based on pressure from the pilot pump. When I dead headed the pump each outlet built 1000-1500 psi right on start up and then immediately dropped to near nothing. Here's a link to 1 of 2 pump test. Even at this little bit of pressure the boom, stick, bucket will operate. But the tracks really can't move and the swing doesn't even try to move. I'm assuming there's not enough pilot pressure to maybe unlock the brakes?