oil pressure sending unit

[lively]

what the ? i got a new oil sender for the 351 and before it was showing 0 -10 and i picked a new one up for a 86 f150 w/ 5.8Lfrom auto zone and the thing reads 80 psi ! and never moves .. i did notice when i removed the old one it had a reducer
from the pressure stem to the old sending unit , new one is like 1/2" NPT and the reducer was like 3/8" npt ... is there a special kind or something for boats ? new one on me

[Wulphie]

what the ? i got a new oil sender for the 351 and before it was showing 0 -10 and i picked a new one up for a 86 f150 w/ 5.8Lfrom auto zone and the thing reads 80 psi ! and never moves .. i did notice when i removed the old one it had a reducer
from the pressure stem to the old sending unit , new one is like 1/2" NPT and the reducer was like 3/8" npt ... is there a special kind or something for boats ? new one on me

Not so much a difference between auto and marine but I believe some gauges use different range of ohms. You have to match the ohm range of the sending unit to the ohm range of the gauge.

Your gauge might operate in a range of 20-30 ohms and the sender you bought might be 40 ohms at idle.

Just a guess though. . .

[Jetlink]

There are two different types of switches, there is your basic "on/off" where it can only sense that there is either no oil pressure or something other than zero PSI. It sounds like you might have gotten that kind of switch.

There are also ones that vary the resistance with the amount of pressure thereby telling you how much oil pressure you have.

[michael hunter]

The oil sender must be a marine sender if you use an automotive part it will just peg the needle.

[DKJBama92Mariah]

Like said above, an automotive oil pressure sender uses a different ohm range. On top of that, Ford had funky sensors as well that aren't really a sender but a a switch that simply goes between good pressure and no pressure. I would order one from skidim. If you absolutely can't wait (I'll admit I couldn't) you can go to Advance Auto Parts and have them cross reference Sierra Part# 18-5899. They can order the equivalent part and have it the next day. I went in and ordered it on a saturday afternoon and it was there sunday morning. Downside was the sensor was $57, almost twice the online price.

NOTE: do not use teflon tape on the sender threads. the threads need a good ground to the engine for the sender to read correctly.

[lively]

Like said above, an automotive oil pressure sender uses a different ohm range. On top of that, Ford had funky sensors as well that aren't really a sender but a a switch that simply goes between good pressure and no pressure. I would order one from skidim. If you absolutely can't wait (I'll admit I couldn't) you can go to Advance Auto Parts and have them cross reference Sierra Part# 18-5899. They can order the equivalent part and have it the next day. I went in and ordered it on a saturday afternoon and it was there sunday morning. Downside was the sensor was $57, almost twice the online price.

NOTE: do not use teflon tape on the sender threads. the threads need a good ground to the engine for the sender to read correctly.

thank you ! , i guess i shouldn't have put thread compound on the threads cause the auto sender started spraying oil on the filter , i ordered one on ebay for 22$