555D Engine in but more issues

Just replaced engine with rebuilt. Started right up. Ran hour or two. Current problem is uneven rpm. Sitting still and running, will vary as much as 200 rpm. Run fine for a minute then slow down then up again. I stopped it and restarted a few times and a couple times a few seconds after restarting it died, but restarted fine. Any ideas on this one. Ran perfect before new engine. Only replaced due to water in oil problem.

Other problem is hydraulics, which worked fine before. My mechanic who drove it over after getting it all back together said I need to add hyd fluid as hyds were slow. I ran low on alot of machinery and slow is not a sign of low fluid. Jerking is, when extending a cylinder and you start to suck air. I think it has something holding the bypass open. I have to up the rpm to get things to move and no pressure unless you rev it up. Then nothing like it was a few days ago. All that was done to the system was take off pump and tank and replace, in engine change process. Any ideas on this and where to look? I'm thinking the first relief valve should be on loader control valve. They may have gotten a chunk of something in the line when it was open.



I will top off tank tomorrow and try it again. At present the machine is useless as a backhoe/loader. I'm close to 8 or 9 grand so far on cost. Will get bugs out but it is kind of a pain. Thanks,, LB

To add on the engine fuel problem: Started cold this AM. Fired right up on one turn of engine. Then every 6 to 12 seconds engine will drop 100 to 200 rpm then in a couple seconds will go back up. Shut off engine and restarted---ran about 5 seconds then dies like you turned it off. Will restart like nothing happened and won't die again unless you let it run awhile and shut off and then restart right away. Just happened after system was removed and reinstalled on new long block engine. Air or dirt? LB

I would be checking the inlet screen to the hydraulic pump for restriction. Same thing on the fuel system. The surging could well be because of an inlet restriction.

Agree.

Rod

injector pump sucking air? starving for fuel, bad govener ring, stopped up return, leak in fuel line?

No nothing about the hydraulics on that model.

Think I found the problem on the fuel issue. Sealing washers are leaking on hand pump if you pump it hard and fast. If fuel can leak out air can suck in. Will replace with new and see if that solves problem. LB