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Discussion Topic:
Oil Pressure Sending Unit
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joe b |
07-25-2012 @ 9:59 AM
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Member
Posts: 389
Joined: Oct 2010
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I did a rebuild on my '41 engine. Cleaned the oil pump and reinstalled. I also purchased and installed a new oil pressure sending unit as my old one was rusty and dented since the rest of the engine looked so good. Upon fire up the oil pressure gauge would only register 20 psi at idle and revving only barely raised the pressure. Below the sending unit in the block was a pipe plug. I installed a remote oil pressure gauge and had 50 psi at idle and 70 psi revving up. I replaced this sending unit with a new one. Same problem-only 20 psi at idle. The original gauge was fine 50 to 70 psi. Both of the replacement senders had "80 psi" stamped on them. Any suggestions?
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supereal |
07-25-2012 @ 2:43 PM
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Senior
Posts: 6819
Joined: Oct 2009
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The oil pump is a 40 lb unit, and your new sender is designed for the later, 80# pump. To my knowledge, the 40# sender is not being reproduced, leaving you with the choice of using the original sender, or putting in an 80# pump. As you have confirmed the actual pressure, I'd just leave the new sender in place, as you know the "real" pressure.
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Old Henry |
07-25-2012 @ 3:34 PM
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Senior
Posts: 738
Joined: Apr 2010
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As Supereal hinted and others have said outright: "If you don't like the reading on your oil pressure gauge put a piece of tape over it." That would be especially so since you know the pressure's fine. Or, clean up the old sender and put it back in.
Old Henry (The older I get, the better old looks.)
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40 Coupe |
07-26-2012 @ 5:00 AM
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Senior
Posts: 1688
Joined: Oct 2009
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If your original dented sender works fine and it does not have any markings on the square base then it most likely is 40# since all of the 80# senders are marked. I would suggest if the original sender works clean it and fill the dent and paint the sender body to the original cadmium color and reuse.
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joe b |
07-26-2012 @ 5:02 AM
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Member
Posts: 389
Joined: Oct 2010
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Please bear with me guys but I don't understand. What was the old unit that I replaced? It showed oil pressure well above 40 psi. Unfortunately I no longer have it. And why would the new unit which is rated at 80psi only show 20 psi? Super,I agree;I will live with the sender now that I know what the pressure is
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TomO |
07-26-2012 @ 9:45 AM
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Senior
Posts: 7271
Joined: Oct 2009
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Joe, The stock dash unit on your 41 Ford was designed to work with a 40# pump and 40# sending unit. The maximum reading is 50#. If the sending unit is changed to an 80# unit, the gauge will read approximately half of the pressure at the sending unit. IE: if you have 30# at the sending unit, the gauge should read 15#. If you have the short body oil pump, it is the 80# pump. The 40# pump has a longer body. If you have the 80# pump, you need the 80# sending unit. If you have a non-stock gauge, I cannot help you, because I do not have the specifications.
Tom
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joe b |
07-26-2012 @ 10:32 AM
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Posts: 389
Joined: Oct 2010
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I get it now. Thanks I do have stock gauges.
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TomO |
07-27-2012 @ 7:56 AM
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Senior
Posts: 7271
Joined: Oct 2009
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Joe, You threw me a curve with your initial post stating that you were reading 70# pressure with the old sending unit. The markings that I have seen on original cars are 0, 20, 50, with 20 being the center marking.
Tom
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joe b |
07-27-2012 @ 1:22 PM
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Member
Posts: 389
Joined: Oct 2010
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Tom O The 50 psi and 70 psi readings were on a remote (test)oil pressure gauge that I installed in a fitting on the block below the stock sending unit. There is a pipe plug that is removed for access.
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