This is a somewhat common problem; we used to think the oil pickup tube seal would fail and allow oil drainback after some time, with subsequent delayed prime. Do you notice it happening worse if the car is parked facing uphill?
Dr. Dan suggested to me to a) try heavier weight oil, b) overfill crankcase by approx. 1 qt. I like running the lightweight (0w-30 I think) full synthetic so overfilling the crankcase seems to help. Good that you have a mechanical oil pressure gauge hooked up. Important Q for science:
---What is the mechanical oil pressure at startup when the low oil press light is lit?--- That will help us ascertain whether it is actually causing a problem or not.
Quote:
Originally Posted by jetfiremuck
1. Is it possible that the slipperyiness of the synthetic oil is causing drainback thru the pickup tube into the oil pan.
|
Probably not that it is synthetic. If anything, probably more related to the viscosity value of the oil.
Quote:
Originally Posted by jetfiremuck
2. Ive removed the oil press relief valve and spring and checked all good there.
|
No scuffing? Current thought is that the scuffing is what allows loss of prime, esp. long period, esp. when parked facing uphill (long oil pickup tube, oil pickup a long way from the oil pump).
Quote:
Originally Posted by jetfiremuck
3. Ive run the engine since refresh using synthetic oil.
|
Good for you! Full syn oil highly recommended for these.
Quote:
Originally Posted by jetfiremuck
Obviously this cant go on without bearing damage. If i idle up the engine to 1400rpm for a few seconds or so light goes out. Shut off and restart all ok until left overnight.
|
Your mechanical oil press gauge will tell us what is really happening upon startup rather than relying on the dummy light.