The Ford Barn - View Single Post - Cold Oil Pressure Drops to Zero, Then Comes Back

Dave in MN · 03-10-2014, 07:52 AM

I think your initial assessment is the answer: "I wonder if it's possible that the pump is pumping enough of the cold oil into the valve chamber, and the drain back is slow enough, to starve the pump momentarily."
I started my Phaeton yesterday at about 40 degrees with 15w-40 oil in it and the same thing happened. I also have the A-Ford-Able filter. I normally run 10w-30 in it and have started it cold many times and not experienced (or noticed) the momentary loss of pressure, so it has to be the thicker oil. I had my oil level right up to the full mark. I am not concerned with the event.
Concerning the by-pass: Even if the by-pass was holding open momentarily, the gauge would not drop to zero with the cold heavy oil. If the pump is moving cold oil, the gauge is going to indicate some pressure due to the resistance in the oil passages. Dropping to zero indicates "no pumping" ...JMO.
Good Day!

03-10-2014, 07:52 AM	#7
Dave in MN Senior Member Join Date: May 2010 Location: Jordan, MN Posts: 1,416	Re: Cold Oil Pressure Drops to Zero, Then Comes Back I think your initial assessment is the answer: "I wonder if it's possible that the pump is pumping enough of the cold oil into the valve chamber, and the drain back is slow enough, to starve the pump momentarily." I started my Phaeton yesterday at about 40 degrees with 15w-40 oil in it and the same thing happened. I also have the A-Ford-Able filter. I normally run 10w-30 in it and have started it cold many times and not experienced (or noticed) the momentary loss of pressure, so it has to be the thicker oil. I had my oil level right up to the full mark. I am not concerned with the event. Concerning the by-pass: Even if the by-pass was holding open momentarily, the gauge would not drop to zero with the cold heavy oil. If the pump is moving cold oil, the gauge is going to indicate some pressure due to the resistance in the oil passages. Dropping to zero indicates "no pumping" ...JMO. Good Day! Last edited by Dave in MN; 03-10-2014 at 07:59 AM.