Oil pressure drop - need advice
OIL PRESSURE DROP AFTER RUNNING HARD / PERIOD OF TIME
500EFI’s ~ 100hrs since rebuild 308 Dart Iron Eagle heads, 741 cam, AZM Throttle Body, Stainless Marine Exh. Manifolds, No Oil T-Stats, 140* T-Stats. Mobil 15w50 Synthetic oil. Cleaned and Checked Oil Coolers I have an oil pressure difference of 25 psi from one engine compared to the other after running hard for a period of time. Only after 3500 RPM, does the oil pressure gauge slowly drop over time. However, it comes right back after coming off plane and idling for a few minutes. Only the Starboard motor has been doing this since I got the boat 3 years ago and I can’t seem to figure this out. Hoping someone has seen this before and can shed some light and help me solve this. STAR ENGINE 515CI OIL RPM PSI TIME FROM STARTING OUT --------------------------------- 2500 58 1 minutes 3000 58 2 minutes 3500 58 3 minutes 3600 48 3 minutes 3600 45 4 minutes 3600 45 6 minutes 3900 45 11 minutes 4000 40 12 minutes 4000 40 13 minutes 4500 40 14 minutes 5000 33 15 minutes - then back to idle 1000 20 1 minute 1000 25 1 minute 1000 30 2 minutes 1000 35 2 minutes 1000 40 3 minutes PORT ENGINE 509CI OIL RPM PSI TIME FROM STARTING OUT --------------------------------- 2500 58 1 minutes 3000 58 2 minutes 3500 58 3 minutes 3600 58 3 minutes 3600 58 4 minutes 3600 58 6 minutes 3900 58 11 minutes 4000 58 12 minutes 4000 58 13 minutes 4500 55 14 minutes 5000 50 15 minutes - then back to idle 1000 40 1 minute |
My guess as I`ve had this issue
You`re aerating the oil for some reason.
How deep are the oil pans, is the pickup shrouded enough? |
Originally Posted by ICDEDPPL
(Post 4604208)
You`re aerating the oil for some reason.
How deep are the oil pans, is the pickup shrouded enough? |
Did you remove the stock oil T-stats???
You need to measure your oil temps. Possibly the oil is bypassing the oil cooler. |
For sure start with oil temps... that tells a lot...
then use mechanical gauge, could be a simple sender. new engines? or have they always been this way? if new cut oil filter open also, just to be sure. Tuned? I know my oil temps changed when engines were running much leaner, maybe one is off.. |
Griff, Full Force - I did remove the T-Stat from the trouble motor (star) during the rebuild. The other motor already had them removed by the previous owner. The oil temps range seem ok (160-190*) from the gauges on my dash. However, the Star motor gauge always shows about 20 degrees hotter after a hard run.
Im going to try connecting a mechanical gauge as suggested and see if the sensor is fooling me . Thanks guys. |
I had an electric sender do that. Put a mechanical gauge on, the pressure was fine.
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Originally Posted by GNJ
(Post 4604235)
However, the Star motor gauge always shows about 20 degrees hotter after a hard run.
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Are you running the stock 500efi program?
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Debris in cooler tubes?
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