I have some questions regarding hydraulic troubleshooting on my machine. Is anyone familiar with the Dynahoe 1900 backhoe?
To be specific, the machine runs well. The problem comes when I try to perform any hydraulic function. Bucket, backhoe arm, outriggers ect. The machine stalls out almost immediately. I'm assuming a stuck valve not diverting pressure is the culprit. But if so, where would I find it? I am an auto and truck mechanic but not a heavy equipment mechanic. I feel that with a little info, I can solve this issue.
I don't know if there are any dynahoe experts here, but it's a very simple machine. How about a little history on the machine? Is that a Detroit Diesel engine? Does it drive normally? Has this been in use, or is it being brought back from the dead?
My particular machine has a 3-35 Detroit Diesel and runs beautifully. It also does drive, with seemingly reduced power. As in it will run fine on the flat, but has a hard time handling grades or hills. The machine has not been in use for years (maybe 15) and sat outside. Prior to startup, I manually spun the engine over by hand before firing. Oil was good, and I replaced the 3 batteries. I also drained the old fuel and filled with fresh diesel. As expected I have quite a few hydraulic leaks, both lines and cylinders. The biggest issue I'm facing is the stalling out when I activate any of the hydraulic appendages. If this is a major problem, I'd like to know before deciding to invest anymore $$ into it.
My suspicion is that the "rack" in the engine is sticking? that's about as much as I know about detroits, I've seen lots of them in pieces but never put one together... Any number of guys can tell you what to do if they see this or you could start another thread if you agree that the engine is lacking power. That 3-53 would rip the pump apart before the engine would stall if it was running right. If the engine stalls without blowing a cloud of black smoke then you're looking at a fuel issue of some sort. Does that have a torque converter so the engine slows down going up a hill? does it slow down even in low gear and is there black smoke when it slows down? Or if you want to wing it, take the valve cover off and free everything up. Be sure your air shut off is working and you can reach it quick.
When you pull on a lever, does the boom move while engine is stalling? Could you have an ice plug somewhere in the system. If it's been sitting 15 years it may have water/ condensation gathered in there. I suppose if it has it would be sitting in a low spot somewhere. If it's in the return line it may effect all hydraulic functions. Just a thought, may be way off. I'm assuming it's freezing there most days this week.
When I pull the boom, sometimes it will move before stalling. If I feather the lever, the machine will pick itself up. Both bucket and backhoe. I do not think the problem is ice related however. While here in Pittsburgh it has been below freezing alot this month, this problem goes back to the previous owner. It was the reason he gave up on the machine. I have the machine in the shop now, so it's in the heat. Delmar, the engine does not blow a black cloud when stalling. Nor does it do it when attempting to climb. According to the parts manual I have to the machine, it is equipped with a torque converter.
It should at least make an effort at global warming/acid rain, I'm sticking with a fuel problem (or governor problem), but I'll leave the rack speculation to the Detroit experts. I really doubt there's anything wrong with the hydraulics. Is the hydraulic pump a gear pump? not a piston pump?
Yes it is a gear pump
I suggest you contact Dave Laing 908-377-4157, he is the most knowledgeable Dynahoe man I know of, he was the dealer in NJ. I sounds like the flow is being obstructed within the hydraulic system. I know the backhoe valve body was made in Germany, it could be the main relief valve is not allowing the oil to return to the hydraulic tank.
Thank you for the contact info. I will follow up with Mr Laing. I'll also re post when I solve the problem so as someone else with this problem may be able to draw from this thread.
I have a 190-2 dynahoe. I'm having same issue with travelling. Can't get out of its own way. I've read that it may be torque converter is really worn but I've also read that there are issues with the modern type of dear on available to us. Some add 30w non detergent oil to the tyranny but I'm hesitant until I hear that from more sources. You should look at Yahoo groups Dynahoe. There's 3 sites that have tons of info. Best of luck to you.
I play with a number of these old Detroit 2 strokes. I am not an expert but heres a couple of items you may or may not have eliminated. Does it have a tach on it? The 3-53 is designed to be run at governed speed while working. Should be screaming at around 2700 RPM and will sound like it will blow any second. Any less and serious loss of power. You could also remove your return fuel line at the tank and hold it while running to see how much return you have. It should have a solid 1/4 inch stream under some pressure if all is well in the fuel delivery system. Also check the 90 degree brass return line fitting where it comes out of the head. It has an orfice in it and sometimes people take that fitting off to reposition the return line. It should have a number stamped on it. 60 if I remember correctly. The gear fuel pump charges the secondary filters and the injectors to about 60 PSI. Sometimes the fuel line from the gear fuel pump to the secondary filter collapses inside. Most were steel lines when new and many have been changed to fuel hose and they often crap and fold internally under the pressure. If your fuel supply is good I would suspect a sticky governor especially if it sets around a lot. I had one just a month ago that would not run under load but idled perfectly. It kept running out of fuel, the lines were good, but the return flow would stop when I revved it up. After going thru everything I could think of I finally stuck a electric fuel pump in line to make priming easier. Thats when I notice fuel leaking out from the back size of the fuel pump when the electric was pumping against it. Turns out the fuel pump was sucking air thru the seal when it was revved up but worked fine at an idle. $4.85 later it ran fine.
The 1900 dynahoe has a heavy lift switch on the control panel by the throttle, if I remember correctly it says crane and dig. It must be set at dig or it barely even starts. As a matter of fact I am surprised it did. I hope this helps