anyone check boost on a 315B lately? 3046T engine. Spec is 14 psi according to dealer. however, I know boost is one spec that use to be quite elusive on many Cat machines.... I could almost never get rated boost on an engine in chassis. We had a low power report. I think most of the issue was governor actuator calibration and cable adjustment (weren't getting high idle rpm). Also Pilot pressure was about 75 psi low. Was only giving 2 psi boost before adjustments, 6 psi after adjustments. Did a top end set (a couple of exh valves were out by about 5 thou- nothing alarming) boost now hitting 7 psi maybe if you bring the load on very very gradual. turbo is ok (feels ok grabbing the shaft - haven't put a dial indicator on it - no oil in the intake- no black smoke. unplugged the PRV and used boom raise to drag the engine down past full load each time. no issue with the pumps - they would happily shut the engine right down if I keep going Engine has 8000 hours. Got new nozzles last year but inj pump never touched. We get some white smoke at cold startup, but never any black smoke. Makes me think inj pump is weak, if there is a problem at all. If it were a turbo issue there would be black smoke (no AFRC or smoke limiter whatsoever on this engine..tier zero emissions I guess) Machine has some downtime this winter and pondering just leaving it - sending back to work in the spring - although if we were ever going to send the pump out... now would be the time. next going to test boost on the D5G here -same engine similar HP... going to be tricky to load that smoothly though.
Got an engine Serial Number ..?
5XK27735 - thanks! just looking at my notes - spec was 23.7 in Hg which converts to 11.7 psi. I was converting wrong. We're at 700' above sea level.
You need to be careful here. There are 2 specifications for the boost pressure. At full engine load (max RPM of 2350 or thereabouts) the spec is 23.7" Hg which equals 11.64 psi. The spec permits it to vary between a ceiling of 27.2" Hg (13.36psi) & a floor of 20.1" Hg (9.87psi). At Torque check speed (1500RPM) the nominal boost is 20.7" Hg (10.17psi). The spec permits it to vary between a ceiling of 23.8" Hg (11.69psi) & a floor of 17.6" Hg (8.64psi). Hope that helps. IMO 700ft above sea level should not affect how this engine runs at all as it is turbocharged. Now if you'd said 7000ft that WOULD have made a difference. Another thought. How good is your boost pressure measuring gauge..? At such low pressure it would not take much for it to give a reading that was well off. Should be easy to boost check the D5 - stall the transmission in 3rd gear with your foot on the brakes and have at it.
thanks Nige. The ceiling/floor specs and reminder about torque chk speeds give me a little more confidence with the numbers. the D5G is hydrostatic, so we'll lock the brakes on and try to figure a way to get the pumps to stroke enough to load the engine. I have a little pwm generator I can stroke them with if the ECM wont let me. I know from doing xover relief tests, the hystat ECM only strokes the pumps very slightly when the park brake is locked on via ET.... must be a way around that though... can always disconnect the hoses to the brakes or just drop the coil off the park brake solenoid stem without unplugging it... or plug another solenoid into the harness there to provide an electrical load. (unplugging it causes an active fault) thanks again
If locking the brakes is a problem put it against something solid (big rock or tree or whatever) and have at it then ......... I thought if you released the park brake, then engage drive and stand on the service brakes the pump would still upstroke..? TBH hystats are not something I've worked on much.
oddly, the brake pedal has almost nothing to do with the brakes on the G series. It's just a position sensor that destrokes the pumps back to N...same as just putting the handle back in N except right at the very bottom of the pedal travel, when you push the pedal down fully, there is a microswitch that dumps park brake release oil (same as the P switch) so, Cat's way to stall is to use ET to lock the park brake through the config screen. But even then, you only get minimal stroke- just enough to put a few GPM across the reliefs. I'll probably just push some dirt with it, yes.