Oil Pressure Gauges Only Working in Engine Rooms

[Bob Bradley]

Just a word of warning on mechanical ER gauges. 2 seasons back I had a SW tranni pressure gauge failure in my ER. It failed internally and pumped all the tranni oil out, resulting in a $17k rebuild. Needless to say, I have eliminated all the gauges down there. Had it been the main engine gauge it would have been a hell of a lot more costly than that.

[adt2]

Just a word of warning on mechanical ER gauges. 2 seasons back I had a SW tranni pressure gauge failure in my ER. It failed internally and pumped all the tranni oil out, resulting in a $17k rebuild. Needless to say, I have eliminated all the gauges down there. Had it been the main engine gauge it would have been a hell of a lot more costly than that.

Ouch. So you just have the helm gauges now? I would've thought the ones in the ER connected directly would be the most reliable...I guess I don't really understand what those gauges are actually doing. I had no idea the gauge could/would pump fluid - I thought they were just reporting what they measured.

[Avenger]

Ouch. So you just have the helm gauges now? I would've thought the ones in the ER connected directly would be the most reliable...I guess I don't really understand what those gauges are actually doing. I had no idea the gauge could/would pump fluid - I thought they were just reporting what they measured.

They have to be connected to pressure in order to measure pressure. So, if they fail they can release that pressure. The gauge doesn't do any pumping, the oil pumps to that. But a gauge failure can be very similar to removing a gallery plug.

[Bob Bradley]

Here's what greeted me in the ER (along with a mess of oil and a blown tranni)...

IMG20220718112801.jpg

[adt2]

So I may not be smart enough for this project lol. I'm trying to follow along with a YouTube video that explains how to troubleshoot this issue. In a nutshell, it says 1. Use a multimeter to test for 12v at the gauge (ground and ignition studs); if no power, stop and figure out why 2. Use a short length of cable to verify full deflection of the gauge when ground and sender posts are shorted; if not then the gauge is bad 3. Repeat step 2 at the sender; if the gauge deflects then the sender is bad, else the wiring is badTwo days ago, I got 12v at both oil pressure gauges but didn't have time to go any farther.Today I have 12v port and less than 5v starboard (but no other electrical issues I'm aware of today). Port gauge deflects when ground and sender are shorted; starboard side - nada.I'm not sure I'm looking at the right sender in the engine room - there are two oil pressure gauges on the helm and it's the "Oil Pressure" ones that don't work (not the "Drive Oil Pressure").Anyone have thoughts?

[Play'N Hooky Too]

The drive oil pressure sender should be on top of the transmission at the rear of the engine. The oil pressure sender is usually located low on the side of the engine below the exhaust manifold. Mine are both on the starboard sides of the engines. The sender in your picture looks like the drive oil pressure sender. It's hard to tell from the picture, but it looks like the connector on the red wire is poorly crimped. It looks like someone crimped it with a regular pair of pliers or a wrench handle. I would do myself a favor and invest in some proper crimping pliers and heat-shrink connectors. That eliminated about 90% of my electrical issues.

The heat-shrink connectors are not that unreasonable if you order them in bulk. One of those paint-stripper heat guns from Harbor Freight works great for shrinking them down without scorching the wires.

[adt2]

Thank you, that’s actually super helpful. I thought I was probably looking at the wrong sender. Regarding the tools and supplies, I bought a whole mess of those when I bought the boat. I have a proper set of crimpers, strippers, marine grade heat shrink, connectors with crimp and heat shrink built-in, etc. Once I figure out what the problem is, I am more than equipped to repair it, I think.

[Bob Bradley]

Which engine do you have? That will help us advise on where to look for the sender. I can tell you where to look on a 6v92. Once you find it, if the wires aren't loose, you've either got a bad gauge, bad sender, or (least likely) a broken wire somewhere in the harness.

The easiest fix is to just replace both the gauge and the sender. They're not that expensive.

[adt2]

Which engine do you have? That will help us advise on where to look for the sender. I can tell you where to look on a 6v92. Once you find it, if the wires aren't loose, you've either got a bad gauge, bad sender, or (least likely) a broken wire somewhere in the harness.

The easiest fix is to just replace both the gauge and the sender. They're not that expensive.

12v71TI

my goal is to replace all of the gauges at some point. But since that appears to be a more in-depth project than I suspected, my interim goal is just to get my current gauges functional again.

[Captain Ralph]

12v71TI
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Centered under the stb exhaust manifold.

The top oil hose to your turbo comes off of the same block.
You can follow this hose down to your senders.