Oil Pressure sensor.

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Oil Pressure sensor.

Post by wschneid »

The starboard engine on my 32' FB with Chrysler 318's gets pegged to the right when I start the engine. Could this be a sign of a faulty oil pressure sensor? And where is the sensor located on that engine? The engine runs fine, but the oil pressure showing that high concerns me.

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Re: Oil Pressure sensor.

Post by Fastjeff »

That might be an accurate oil pressure reading if the relief valve in the oil pump is stuck closed.

I would stick a second oil pressure gage on it temporarily and see if that gage went way up as well.


PS: If I'm righ you should change the oil immediately.
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Re: Oil Pressure sensor.

Post by bcassedy »

The location of the oil pressure switch is at the rear of the engine. Back in 2018 I was going to switch to an electronic gas pump. Part of the process requires an oil pressure switch be electrically in line to the pump so that, if the engine should die (or just the ignition be left energized - engine not running) the oil pressure switch would open, breaking the circuit to the gas pump (and preventing a flood of gas spewing from the carb - bad thing! :roll: ). This is a pic of the "stack" of pressure switches. Your original one would be first (second?). The 3rd (top - canister) is the one I added - but ultimately didn't need as I located a source for the mechanical pump and used that.
Strbrd oil pressure swtch stack - 50% of 25%.jpg
Note - I did try removing the original switch but it seemed I'd foul up the threading / break off the original switch in the process. Opted to just "stack" the new one, which has worked well (it's just sitting there, not being used - the engine, other oil switches below, and gauge don't seem to care.
Last edited by bcassedy on Wed Nov 18, 2020 2:15 pm, edited 1 time in total.
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Re: Oil Pressure sensor.

Post by jralbert »

In this discussion of oil press switches one thing to add. They are failure prone. Oil will shoot out. Maybe it's vibration - I don't know. Check them often and have a spare or two on hand. If one were to let go on a trip, you'd lose vital oil quickly. Which is why one monitors oil press and temp and have a temp alarm.
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Re: Oil Pressure sensor.

Post by ddependo »

Good point, to have a couple of spares. Anyone have the part # for 318 engines?
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Re: Oil Pressure sensor.

Post by Tuggle »

Check your ground, inspect the wire, clean the terminals.
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Re: Oil Pressure sensor.

Post by javalin390 »

Also note that if you have more than one switch, one of course for the gauge, one for the engine alarm, if equipped, and possibly another for engine shut-down, as in the case of boats with electric fuel pumps OR this same switch was originally used to complete the field circuit on the old style Chrysler voltage regulator.
#3619738 or 4417702 - this is the simple, small on/off oil switch for engine alarm, voltage regulator, or fuel pump shut off. NAPA carries hundreds of different switches so I'm certain they can match it up (most use the same threads).
#3619101 - for gauge
#3527242 - for gauge--both of these part numbers are listed in the Chrysler parts manual, and depends on a certain engine option, but I'm not sure what that engine option is.
#3619617 - for gauges (2), this one is used on dual helm boats and will not read correctly if used on a single helm ( not sure if it will read double or read half)
#R020006 - this is also a dual helm sender from Crusader Marine, interchanges with Chrysler 3619617.
Once again, NAPA or a speed shop (i.e. Jegs, Summit Racing) could probably cross them into a newer, available part number depending on the brand of gauges you have and the ohm range (a common ohm range is 0-90).
Hope this helps.
Jim Elias
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