98cobra+75280z Posted December 28, 2012 Share Posted December 28, 2012 I recently rebuilt my '82 l28et for my '77 and am having oil pump issues now. The car idles fine but with cold oil my mechanical only sees around 20 psi and as it warms it goes down to 12-15 like it use to. My worry worry is that with cold oil the car use to see 45-50 psi at idle and increase with revs to 60 or so. With revs the pressure never goes above 20 psi. I installed the pump and shaft like the "how to rebuild your datsun OHC" book states but ran into a problem with the oil squirt hole not lining up with the punch mark on the pump shaft gear. With the marks lined up the dizzy shaft end isn't even close to being lined up. When I line the tang of the dizzy side up to where it needs to be the marks on the shaft and pump housing no longer line up. The pump is off an '83 turbo motor where as the shaft is from the '82 motor. I don't see how the shaft mark needs to be lined up with the pump housing since the shaft just spins along with the motor but maybe I'm wrong in this thinking. I am planning on getting a different gauge to see if maybe my gauge is faulty. Taking the oil cap off I do see oil squirting up to the cam but I am not sure if it is a sufficient amount. Any ideas on what may be causing my lack of oil pressure. Oh and the oil pick up tube is free and clear from debris as well. Thanks guys, Kevin Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted December 28, 2012 Share Posted December 28, 2012 I've heard of the gear spinning on the oil pump shaft. I've never experienced it myself though. Quote Link to comment Share on other sites More sharing options...
Xnke Posted December 28, 2012 Share Posted December 28, 2012 If the dots don't line up, that spindle shaft is either twisted or the gear has spun. I can't imagine there would be sufficient clearance even with good oiling for the shaft to spin easily on the gear, but a little slip could certainly cause the problem you're having. Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 28, 2012 Share Posted December 28, 2012 Did you keep the 77 pressure sender or make the 82's work? Lots of variation in the oil pressure senders. I "gained" 30 psi when I installed a different sender. Quote Link to comment Share on other sites More sharing options...
Tony D Posted December 29, 2012 Share Posted December 29, 2012 The gears will spin. It affects timing, not pump output pressure...save for the millisecond the pump slows while the spindle slows in relation to the gear rotational speed. Seen the gear jump anywhere from 7 to 180 degrees on a dyno pull from force reversals on hard drop throttle under full power. Quote Link to comment Share on other sites More sharing options...
johnc Posted December 29, 2012 Share Posted December 29, 2012 I did think it was kinda funny... The oil pump AND distributor drive gear is spinning on the shaft and the only issue is oil pump pressure? Quote Link to comment Share on other sites More sharing options...
fast-datsun Posted December 29, 2012 Share Posted December 29, 2012 it could be a bad relief spring in the pump or Too much bearing clearance on the mains..I would get a new pump ASAP.... Quote Link to comment Share on other sites More sharing options...
98cobra+75280z Posted January 2, 2013 Author Share Posted January 2, 2013 I swapped the pressure relief spring and the pump is back to normal. Thanks for your input guys. Regards, Kevin Quote Link to comment Share on other sites More sharing options...
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