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| The 4020's hydraulic pump made that sound from the day it was new. I think it is a part of the design as whichever piston is the free-est floating in the pump body will be the first one to fall down against the cam ring & if it's output is enough to make up for the parasitic losses & leaks in the system, it will be the only one to rattle & knock & do any pumping. I changed the belts on the front of the engine a few years ago (it is semi-retired now) & the coupling parts were all in good condition at that time. It still rattled & knocked before & after that, just as it did the day it was delivered. Dave | |
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