1968. Pontiac lemans. 350 engine. 4bbl carb. New rods and lifters. HEI distributor. Put 10w30 oil in engine. Oil light will stay on when car is in drive and idling. Oil light will go off when car is in drive and under load. Oil light will flicker on when car is in park and idling. Sounds like the oil pump is going. Thoughts ??? Would I help the oil pump by switching to 5w30 grade or something else? Tx. Jimb
Oil pressure light flickers on
- Thread starter j5ball
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Zimgxp
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If the oil pump is new, I would suspect a bearing problem
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Install a temporary oil pressure gauge to make sure the sender isnt going bad. If you get low readings swith to a 10W40 oil to see if that helps. Otherwise it could be the pump and also the bearings, rod and main.
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Too Fast
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This^^^.
Does it only flicker at hot idle? Classic sign of low pressure. Sometimes it's a bad sending unit, but not always. The sending unit will turn the light on when the oil pressure is lower than about 7 psi. Not sure what the exact spec is, could be as low as 6 psi. Healthy Pontiac engines develop at least 25 psi oil pressure at hot idle, 800 RPM or so, with 10w30. 10w40, a bit higher.
Your main source of oil pressure is the main bearings, then the rods. Of course, the oil pump has to be able to develop the pressure needed. Your oil pump screen could be obstructed.
By new rods and lifters, do you mean pushrods or connecting rods. Huge difference there. New lifters and pushrods won't do anything for oil pressure.
Nice car, our summer car is a '68 Le Mans convertible with a 400, but also the stupid, indestructible 2 speed powerglide and horrible 2.52 rear gears.