The Stovebolt Site Forums The Shop Area Engine Shop 216 breathes again!!!!!

Well, Friday was mine and my wifes anniversary so I thought it would be a good time to try to fire up the "new" rebuilt 216. She came to life on cue----what sweet music. We ran it for about 30 minutes, shut her down, readjusted the valves, and tried her again. Lot of bad sounding noise deep in her bowels----like rods knocking. Did not hear this at all when originally running. Pulled the distributor and spun up the oil pump again which was moving oil up to the rocker arms. Ran it again, sounded fine. Came back a coulple hours later same noise when I cranked it. Seems like the pump won't hold a prime. Has anybody else experienced this. Any thoughts would be appreciated. Thanks

just bringing this back to the top, looking for help

What's the oil pressure while this is happening? You might have an air leak on the inlet side of the pump that's causing it to lose its prime. Don't let it knock for very long once it begins, as those babbit rods won't stand much pounding, and the crankshaft can be damaged in a hurry. Also, a clogged inlet screen will drop oil pressure, but if it's newly-built, that shouldn't be a problem. How much work has been done to it? New/reconditiond rods, reground crankshaft, etc., or just an in-the-frame freshen-up? Since it will pressurize by running the pump faster than idle speed, I'm betting on an air leak on the inlet side.
Jerry

Thanks Hotrod. Was a complete rebuild. Bored .030, crank turned, new head and cam. Insert bearings in the rods. What is the fix for and "an air leak on the inlet side" of the pump?

Was there a lip on one of the main bearings (thrust) bearing to stop the foreward and back movement of the crank? If not on the bearing, was there a seperate package with some half moon shaped pieces to be inserted before you put the main cap on. I have heard this noise when the thrust bearings are worn. Stops when you push in the clutch because crank is pushed foreward by pressure on clutch mechanisim. Just an ides, I could be off base.
Truck Tinker

I don't remember how oil gets into that pump, whether the pickup tube bolts to the pump, or there's a passageway in the block from the pickup screen to the pump, but look for anywhere air could be drawn into the inlet side of the pump along with the oil. A leaky gasket where the pickup screen bolts to the pump is the most common cause, but a cracked pipe on the pickup could happen, etc. Just make sure the pump sucks up only oil, not air along with it!
Jerry

With my 49 216, the oil pressure fluctuates as the motor speeds up. Oil pressure tends to drop low when the engine is at idle and returns to normal as rpm is increased. Is this normal for these engines?