How to remove and clean engine oil pressure switch

[jrsick]

Boat is 2001, 3.0LX engine. My oil pressure gauge indicates zero pressure. Gauge comes alive when powered and the needle moves to zero. It doesn't move off of zero after start. Oil level is good. I ran it for 20 minutes and didn't hear any unusual clatter in the valve area so I decided/hoped that issue is switch or gauge. I've got a 40 minute drive to the dock this week so I want to ensure that I bring all the tools, knowledge, and ideas when I go. I plan to check the gauge first, and, if it is good then clean out the switch. My questions: 1) do you just unscrew the switch with a wrench? Anything special about removal? SELOC gives troubleshooting steps but doesn't discuss basic task of removing the switch. 2) is seafoam and good cleaner for the switch?
I've got confidence that I am getting oil, but there's just something about a gauge reading zero that gets my attention.
Any advice or other experience would be most welcome.
r/Randy

[mcoffey]

I have never heard of anyone cleaning an oil pressure switch. They generally work or they don't and when they don't, replace it. If not mistaken, it is just a diaphragm inside that controls variable resistance. So the wire that is connect is just ground and the more pressure applied, the less resistance there is making the gauge show higher. Open circuit mean no reading at all. The best test to verify it is the gauge is to just disconnect the wire and short it to clean metal on the block.
With wire disconnected, you should show 0 on gauge, with grounded, it should show max (normally 80 or so).
If you do not see this behavior, you have a gauge or wiring issue. You can then trace out the wire and maybe do an ohms test on it from the gauge to the sender to see if there is a break.

As far as removal goes, yes, it just unscrews. It is pipe thread though so you should use Teflon pipe tape when putting back in.

Good luck!

[ss3964spd]

Randy, oil pressure sending unit is bad you can't really clean it, just replace it. If you're not getting any alarms, and the engine hasn't started making noise or, worse, simply stopped running, I think your assumption is correct; faulty sending unit, or gauge, or wiring. Zero reading at the gauge would freak me out, too.

[jrsick]

Thanks for the replies and great info. I am going to give it a try on Thursday.