Join Date: Mar 1999
Location: The Island of Luzon
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Swapping the oil pressure sender first?
Doubtful there is that much sludge causing a problem with oil pressure rtising.
Oil P senders on Z's are notorious for not sending the correct signal.
Verify with a MECHANICAL gauge! Take a "T" and put the mechanical in parallell with the sender, and make sure it's full of oil on the line so you read when the pressure in in the gallery, and not building up the mechanical's capillary.
Chances are, your pressure is fine.
10-15# at idle is normal. And the rule of thumb is 10# per 1000rpm in the L-Motor.
With the mechanical you can alos watch the bleed-down after the engine is shut off. This will tell you clearances on the rods and crank somewhat.
If it bleeds down really quickly, you may just have excessive clearances, and that's why it takes time to "pump up". In that case, you may be able to swap the oil pump to the 83ZXT w/Auto part, to restore enough flow to get good pressure at idle, without having to teardown anything!
I'd look a little further before tearing into things!
Also, don't be using killer-weight oil, especially multi-vis stuff like 10 or 20W-50. What that stuff does is act like 50 weight when hot, and can cause pump-up problems like you say you're experiencing, as the pump is designed to pump 30wt from the pan, and 50 wt doesn't draw as well. That's why so many car companies now run 5W stuff: on cold starts, the oil is EVERYWHERE very quickly after cranking/startup. Cuts wear, and lowers friction losses.
Oil is very misunderstood...
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