| fordEFV8 | -- 04-24-2026 @ 2:25 PM |
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Just chained oil using 10w-30 adding some ZDDP. Started up with pressure showing a little over 20 on the gauge. Drove it for awhile noticing pressure drop to about 10. Checked dipstick level, right on the full mark, no runs drips or errors I could see. Engine temp gauge running between 1/2 and 3/4 marks, 80 degree day (FYI). By the original "Service Data Handbook" it says normal oil pressure should be 30 psi. Should this much variance be expected? I expect more pressure to start off with than 20 and more than 10 when hot?
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| carcrazy | -- 04-24-2026 @ 3:21 PM |
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These pre-war Fords should show somewhere between 20 and 30 PSI of oil pressure when warmed up and driving. When idling it is normal for the oil pressure to drop down some. If you use a straight SAE 30 monograde detergent motor oil with ZDDP additive, you might notice slightly higher oil pressure. The original electrical oil pressure gauges have a tendency to read a little low. To put your mind at ease, you can always install a good quality mechanical oil pressure gauge under the instrument panel. Borg-Warner makes an excellent illuminated gauge that you will be able to read at night.
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| JayChicago | -- 04-26-2026 @ 1:59 PM |
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I think what you are seeing could be considered normal for our cars. You didn't say, but I assume the readings you are talking about are at idle. When up to temp, my original, not rebuilt engine shows 20-30 psi when driving, but drops to about 5 psi at idle. Not unusual for a flathead with miles on it. An engine with wear will move a larger volume of oil thru the bearing gaps, which drops pressure some. I have read that these engines have no need for high pressure, just need enough pressure to keep oil delivered to all parts of the engine.
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| fordEFV8 | -- 04-26-2026 @ 5:46 PM |
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thanks for the suggestion.
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| lawrie | -- 04-27-2026 @ 10:23 PM |
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some real world oil pressure figures, 34 3w, original babbit engine, cold idle 30-35 psi hot at 50 mph 52 psi hot idle 20 psi, oil 20/50 mechanical gauge, have a later ford electric gauge and sender, it reads all over the place,my mechanical gauge is very close being checked with a master certified gauge. look at my post on the fordbarn ,34 trip Lawrie
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