Good oil pressure sending unit
 

I have a brand new Sierra sending unit and it has a mind of its own... What's everyone using without issues?

If it's acting up you might have a bad engine ground or you used tape on the threads instead of pipe sealant.

If I lightly tap on it it works perfectly until it acts up again. I use thread tape but only on the first couple threads so it makes good contact. My buddies comment to me the other day was "did you put thread tape on any of those oil fittings?" Mine was yeah I just know how to use it so it doesn't look like crap.

I never use tape on those fittings, they ground through the threads. I'd remove the tape and use Permatex thread sealant.

It's not the tape. 1st thought I had was bad ground so I stripped a wire and wrapped it around the housing and went to ground. No change.

Crud In the sender?

I bought a genuine mercruiser off of eBay. I have had terrible luck with the Sierra senders.

Never use tape on a oil sending unit. I thought I lost oil pressure one time, 25 miles from the ramp, came home on one motor at 7mph you do the math, when I got home I tested it with mechanical gauge had 60psi, I removed the sending unit their was a little piece of TAPE:lolhit: in the hole of the sending unit. Never use TAPE!!!

Tape is not a bad thing in the hands of the right person. In some cases adult supervision is required.

I always mount a mechanical gauge at the remote filter on the out side. It's a good check against the electric gauge and also a good way to spot any filter issues

any chance you can post a pic?

I second on the pic, you must have a 3 way fitting but then I would wonder how correct would the pressure reading be at your test gauge. You still have to flow oil thru the output from the oil filter side regardless so the engine still gets lubrication internally. Also what happens if the oil filter goes into bypass ?.

Cant get pic today, 1/2 pipe female tee to filter with nipple, 1/2" male to # 12 AN male for oil line, 1/2" to 1/4" bushing for gauge. Had a filter internally collapse there was a large difference between the block mounted sender and the mech gauge. Likewise, when senders go bad they give false readings before they quit. Gauge is always there for added comfort zone.

Pretty sure it's 1/2", been a long time, might be 5/8

I see you mounted a small analog gauge. I thought you were talking about a hand held mechanical oil pressure gauge and the outlet port was were you did the test at. .