Hi Guys, Hopefully somebody can help me. Just had the pump rebuilt on this digger and the hydraulic guys are saying the engine is down about 20% in power. Hooked a boost gauge up to the inlet manifold and measured 3 PSI at full throttle. With the lack of waste gate on the turbo I was wondering if anybody knows the specs. I've searched through the workshop manual and on line and can't find any information. Anybody know? I was expecting a lot more than that. Thanks in advance
Not sure on this engine but I normally see 15+ in boost pressure at full load. Was the engine under a full load when the boost pressure was checked?
Do a boom up cycle time test. Boom up from the ground to top out with the stick out and bucket open should be around four seconds. When the hydraulics are working the engine properly the boost should be between 12 and 14 PSI. If it wasn't slow before the rebuild and now is, I'd say the hydraulics guys likely didn't set the pump up properly.
Yes, full throttle in power mode with rams extended and only 3 psi.
The guys are having trouble with the pump regulator, they are trying to track another second hand one down. The machine was really slow before rebuild, the cradle, cam and rod were really worn, rest of the pump mint though. 7000 hour machine. They can either get good flow and no pressure without pulling engine RPM down or minimal flow and good pressure. They are convinced there is both a regulator and engine problem. We got 3 psi boost at full throttle in heavy mode with rams fully extended, pump set for high pressure and low flow. Sounds like we might have low boost. Thanks for your info.
Thanks for your reply.
You can't check the power output of the engine that way. The computer and hydraulic system will automatically destroke the pumps to keep from overloading the engine. Disconnect the TVC solenoids on the pump and that should load up the engine and you can check boost pressure that way. It will overload the engine but it will also max out the amount of boost pressure the turbo charger can provide. I would be suspect of the people working on your machine with what you have posted so far.
Hi, Thanks again for your reply. I think the diesel injector and turbo man is heading my way either tomorrow or the next day. Will pass on your information to him. Thanks again, will keep you posted.
You can also set the swing brake and that should put the hydraulics in two stage relief. It will cancel the load sensing and put the pressure able to go over the relief valve.