318b oil pressure questions

Okay, folks I'm back. RosieB12 is running fine after several two hour trips up/down river. Both oil pressure guages, which range from 0-80 lbs, usually run in 40+ range, never quite to 60 as recommended by a manual left by the prior owner. Engines sound good and are running cool. Today at only 2600 rpm's the stbd guage began jumping around and dropped to about 32. So, as I started to panic, I slowed it down to 2000 rpm and the needle steadied down at it's usual 40+ level. Rather than risk a disaster upriver I ran the port engine at 3000 rpm and left the stb at 2000. The same read-out was happening at both steering stations. Anyone have any ideas what's happening and what I should do about it? Thanks.

Plumb in a tee before the sending unit and screw in a direct read gauge.

You eithr have an oil pressure sender problem, or the relief valve in the oil pump is sticking open.

I vote for the first!

Jefff

The beauty of twins is that you can easily swap certain parts as to check one against the other.
Simple test: Swap oil pressure sender units (No teflon tape).
.... or very carefully extend each circuit to the oposite engine's sender.
(the engines will be made system negative common..... so there should be no issues with that)

.

Thanks, ya'll. I'll work on that sender suggestion. By the way, what oil/filters do you guys recommend for these 24 year old engines (650 hours)?

Rosie... Here's some discussion on oil.



http://www.marineengine.com/boat-forum/showthread.php?394891-Proper-Engine-Oil