Oil pressure sender question

[Dougcole]

Yanmar 4lha-stp

Both of my oil pressure gauges have been working intermittently, I had this issue a few years ago on the port side and fixit by replacing the ring terminal on the sender wire, but that didn’t work this time. I think it is time to replace both senders.

My question is, is this a yanmar part or are they tied to my Faria gauges? I was in my local marine store last week and saw some faria senders that look similar, but not exactly, like mine. Asked the clerk and he didn’t know. I have not called my yanmar parts supplier yet. I am hoping they are faria rather than yanmar as they will likely be about 1/3 of the price.


Pic is below, I can't find any numbers on it, but it LOOKS like a sierra sender, which seems odd because I know they are original to the engines.



Any thoughts?

 

[High Wire]

If they are faria gauges then they should be faria senders. Make sure you get the right thread size and single or dual station.

 

[Dougcole]

If they are faria gauges then they should be faria senders. Make sure you get the right thread size and single or dual station.

Makes sense, but the Faria dual station sender looks like this:

The Sierra Dual Station sender looks like this:

Much closer to mine (if you look in my pic above). I'm a little stumped.

 

[Turtle Blues]

Pretty sure if you reverse lookup both part numbers to application they are interchangeable for the Faria gauge.
As High Wire posted differences are thread size and output range for single vs dual station.

 

[kthoennes]

I've been down this road. I spent days chasing down an oil gauge problem after they shipped and reassembled our boat. Finally turned out to be an issue where somebody probably ran out of the correct color so they butt spliced a different color inside a bulkhead between the engine bay and the helm -- TAN, the wiring diagram said TAN! Butt joint was loose but I was chasing the wrong wire for the longest time because of the color swap, and changed my oil sending unit TWICE. (Sierra sender on mine too, although mine was single not dual.) Anyway, I believe Turtle is right, given the photo of what you have now, I'll bet that Sierra will work. It's simple design. I have VDO gauges and I'm replacing one now coincidentally to a Faria. Same sending unit for oil, I ran a test wire to make sure before I went to the trouble of actually swapping the gauge in the helm dashboard. I'm talking about the older Faria gauges though, with threaded posts, not some of the newer "Kronos" models with multi-wire click-in connectors for example. I don't know what those use for sending units.

 

[Barking Sands]

You can bench check those pretty easily. Also you can check what type they are with a few basic steps.

* single helm or dual helm

* American or European

Pasted from TA Diesel Website:
Testing the Oil pressure sender is similar. You should connect a manual oil pressure gauge in addition to the sender being tested, if you do not have a vacant opening, you can use a 1/8th inch NPT “T” fitting for the purpose of the test) Remove the wire/s from the sender and insulate the wire. Before starting the engine connect the ohm meter Pos. lead to the sender connection and the Neg. terminal making a good clean ground connection to the sender’s body. The reading at zero PSI before starting the engine should be 240 ohms. When you start the engine and bring the oil pressure to 40 psi, this should give you a reading of 103 ohms. Increasing the pressure to 80 psi should give you a reading of 33.5 ohms. You may be able to vary the engine speed to achieve the PSI required. Don’t expect these figures to be exact, they are for trouble shooting not calibrating. Note: Dual station senders will have ½ the resistance value of single station senders.

More notes including the European specs are in this link from TA Diesels:

https://www.tadiesels.com/assets/docs/tech/Testing_Sending_Unit_Resistance_Value.pdf

You should be able to use you multimeter and use alligator clips, one to the sender and one to ground and start the engine and check the ohms for smoothness and consistency right on the engine. If the ohms reading is erratic just like your gauge was its almost certainly the sender.

And if you want to bench check I made a short video on how to.
https://youtu.be/6MzsaGGsfwI?si=pyBzefKTVNDMXJ2N

 

[Comodave]

To eliminate all the wiring you can run a temporary wire directly from the sender to the gauge over the deck. If it works then you know it is a wiring problem. If it doesn’t work then it is either the sender or the gauge.

 

[Action]

Looks a lot like an old Ford sender application for a oil pressure gauge (not a warning light) from the 1960s to 1980s.

If correct the design goes back to just after WWII

 

[kthoennes]

Good job Leonard Boddy, whoever you are (were). Now that's some persistent technology.

Huh, seems like he was especially interested in gauge design.

https://patentimages.storage.googleapis.com/11/a8/ce/49b3a91cd8f1dc/US2107560.pdf

 

[tvtfc]

I tended to opt for mechanical oil pressure monitoring solutions on boats or other equipment when I wanted something which would work reliably. Tends to be a little more expensive though. Or did 30 years ago.

 

[tdbentle]

Great video. Thanks for sharing.