Location of Oil Sensing Unit

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dbchristiansen
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Joined: Sun Nov 22, 2015 4:15 am

Location of Oil Sensing Unit

Post by dbchristiansen » Fri May 31, 2019 11:22 am

Hello, Sorry for the dumb question, however while investigating the wiring of a heavily "pre-owned" packard i have owned for a while, i have found the oil sensing wire connected to (-) i guess to prevent it from coming in, perhaps it was failed, i dont know. Anyways, i cannot find the unit to reconnect it or test it. I have a 51-55 packard manual, however it only references the unit and doesn't identify its location. This is a 1951 327 on a patrician (400). Any help would be beneficial. - Dave

Howard56
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Joined: Mon Dec 24, 2012 11:35 am

Re: Location of Oil Sensing Unit

Post by Howard56 » Fri May 31, 2019 12:35 pm

Drivers side of engine, low on block between the motor mount and oil dipstick. Should be in a 4 way brass fitting off the bottom port.
If a 51 there is a light that glows red if no pressure or if it falls below a certain point. The sender connects to ground and has a switch that opens as the pressure goes above a certain amount. Grounding the wire should make the light turn on. Typically the sender is rated at around 6-9 psi which means the light will turn on if pressure goes below that point.
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dbchristiansen
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Joined: Sun Nov 22, 2015 4:15 am

Re: Location of Oil Sensing Unit

Post by dbchristiansen » Fri May 31, 2019 6:49 pm

Looks like my previous owner has blocked it off with a plug. Any specific replacement part recommended?

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JD in KC
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Location: Kansas City, Missouri

Re: Location of Oil Sensing Unit

Post by JD in KC » Sat Jun 01, 2019 5:16 am

I know Max Merritt lists them. Kanter probably has them. If you are on a budget... you might look at NAPA ECH OP6742 and see if that would work for you.

Howard56
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Re: Location of Oil Sensing Unit

Post by Howard56 » Sat Jun 01, 2019 6:39 am

Hopefully all the previous owner did was plug the 1/8 NPT port and the 4 way brass fitting is otherwise intact with oil flow to the filter and valve lifter gallery fully maintained.

In addition to the senders sold by Packard vendors (I do not know how closely they match the original pressure range), the Napa OP 6742 is one several have used. It is low cost but rated at 6 psi which some feel may be a bit low since it will not turn the light on until the pressure level has dropped to what could be a fairly serious range. Others have chosen the OP 6741 which is also low cost but rated at 15 psi. That one may be a bit on the high end and could turn on the light even at low engine speeds when there is no reason to worry.

Your choice as to which might best fit your needs. Both are identical with respect to 1/8-27 thread and a 10-32 stud for the wire. The light on or flickering at idle speeds is to be expected and is even called out in the owners manual as acceptable operation but with a sender at 6 psi it may not come on until the level is dangerously low. One rated at 15 psi may be on too often at idle and low speed traffic conditions and may even get ignored but will give a higher margin of safety.

dbchristiansen
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Joined: Sun Nov 22, 2015 4:15 am

Re: Location of Oil Sensing Unit

Post by dbchristiansen » Sat Jun 01, 2019 9:12 am

Thank you for all the help, i ended up grabbing a direct replacement, i really don't like both Napa options as one could be to low, and the other may get ignored, which doesn't help safety. And yes to follow up the header is maintained, it was just a npt plug on the manifold for the unit.

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