Topic: 1946 ford oil pressure dropping


joeysf58    -- 06-06-2016 @ 8:07 AM
  I have a 1946 for super deluxe. When I start the car the gauge is maxed out. Then I start to drive if for about 8 miles and it get to 0psi. I have changed the oil and using 20-50. The car only has 24k miles on it


TomO    -- 06-06-2016 @ 8:11 AM
  I suggest that you find a mechanical gauge to check the pressure. Your problem could be a bad sending unit.

Tom


joeysf58    -- 06-06-2016 @ 8:48 AM
  Ok. To add to that when I turn it off then on the pressure goes back up. The motor does not make any ticking noise when the pressure drops.


TomO    -- 06-07-2016 @ 7:14 AM
  The sending unit has a pipe thread and it should not have any Teflon tape or other thread sealer on the fitting. The ground connection will be compromised by the Teflon tape.

You could also have a loose connection at the gauge or the sending unit.

If those items are OK, you probably have a sending unit that is failing.

Tom


Old Henry    -- 06-07-2016 @ 8:00 AM
  Here is my illustration and explanation on the Ford Barn of how to check the accuracy of the stock oil pressure gauge with a temporary mechanical gauge (which I eventually installed permanently in my glove box) as TomO suggested: http://www.fordbarn.com/forum/showthread.php?t=68156


Drbrown    -- 06-09-2016 @ 9:35 PM
  My personal experience regarding my '47 OE oil pressure dash gauge: I have an 80 lb. pump and sender unit; use 10w-30 oil; have 35,000 miles. My OE dash gauge had been showing only a few lbs pressure for some time but my aftermarket gauge was showing good pressure. The wiring and grounding tested okay. I installed another (NOS) sender unit .... no change/improvement. I then installed a second aftermarket gauge which read within 5 lbs of the other aftermarket. This seemed to conclude that the OE dash gauge was faulty.

Before buying a replacement dash gauge, and out of curiosity, I took the cover face off the EO dash gauge. It looked like the interior tension mechanizum was "hung-up". I loosened it, and with engine running, re-calibrated the tension so that the indicator approximately matched the two aftermarket gauges. The OE dash gauge has been working fine ever since and its good to see it match the rise and fall of the aftermarket gauges (time to retire one of them).

This message was edited by Drbrown on 6-9-16 @ 9:40 PM


TomO    -- 06-10-2016 @ 7:14 AM
  You can check the dash unit by grounding the wire to the sending unit, the gauge needle should move toward the high end.

joeyef58 original post said that his gauge moves to max when he first starts the car, so his gauge must be working. It sounds like his sending unit is bad.

Tom


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