The Ford Barn

29 Tudor · 03-09-2014, 09:47 PM

Odd situation. I have a oil pressure gauge and the A-Ford-Able full flow oil filter kit. I run 15W-40 diesel oil. Today when I started the engine, the temperature was probably low 50's. The gauge normally goes past 10 PSI when the engine is cold and settles to around 4 PSI at road speed when hot. Here's the interesting thing... when cold, if I rev the engine just a bit, the pressure drops to zero... stays there for a few seconds ... like maybe 10 or so and then comes back up. All this happens slowly because the oil line to the gauge is so small.

Since it comes back up and since once warm, it stays perfectly normal, I'm trying to figure out what's happening. I wonder if it's possible that the pump is pumping enough of the cold oil into the valve chamber, and the drainback is slow enough, to starve the pump momentarily. I was thinking that the bypass valve in the filter was opening and since the gauge is really reading the restriction of the filter, with the bypass open, the restriction is lower but before I installed the filter kit, I never saw the pressure drop to zero but, the outside temperatures were higher as well.

Clearly the pump is working since the pressure comes back shortly. I WAS running with the oil level about half way between add and full. Might try filling to the full mark and see if it makes a difference.

Anyone else ever seen this and have a theory?

The engine is relatively new and very clean inside.

Thanks in advance for any ideas.

Steve

29 Tudor · 03-09-2014, 10:28 PM

Possibly but I wouldn't think that 15W-40 is THAT thick at 50 degrees.

I appreciate the thought though.

Bob-A · 03-10-2014, 06:41 AM

29 Tudor,

On my '29 roadster I have pretty much the same exact set-up as you have with the addition of a can of STP in the oil. I've never had the experience you are having, but I've never driven the car in that cold of weather either. Plus, I keep my oil level right at the full mark on the dip stick.

Bob-A

QGolden · 03-10-2014, 06:44 AM

I know very little of the Full Flow Oil Filter Kit, but I did see similiar symptoms once on a 1960's European Import. After a lot of checking, testing, and removing and cleaning the external oil filter kit and changing the filter, the problem went away. We were pretty sure the filter bypass valve was opening while the oil pressure was high, and sticking open for a few seconds.

Patrick L. · 03-10-2014, 06:44 AM

Did this just start to happen? Like maybe after the last oil/filter change ? I think your idea of adding an extra quart to see what happens is a good one.

29 Tudor · 03-10-2014, 06:53 AM

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My first thought was the bypass opening as well but as I recall from running just the oil pressure gauge before the filter was instilled, as the engine was warming up, I don't remember the pressure dropping like that. I have tried to find an equivalent to the Ford FL-1 filter that doesn't have a bypass to see if that is the problem but it appears that no one makes a filter with a 3/4-16 thread that doesn't have a bypass.

I am going to fill it to the full mark and see if it still happens. As for the oil change, the car was using straight 30 weight and I now run 15W-40.

I appreciate all the responses and suggestions.

Steve

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!

29 Tudor · 03-10-2014, 08:04 AM

Dave,

Thanks for the confirmation!! Glad I'm not the only one. There are no strange noises and the engine runs fine. I think I will start it this morning (high 40's) and let it idle a bit and warm up the oil to see what happens.

With the screen on the oil pump being as fine as it is, it occurs to me that the pump MIGHT be cavitating from the "high" viscosity but I don't know any way to find out. Since it NEVER does it once the oil warms a bit, like you, I don't think it's a major concern but it sure is disconcerting to look over an see the pressure dropping!

I wish I could find a filter with no bypass to eliminate that as a possibility.

Thanks for confirming that someone else has seen the same issue!!

Steve

29 Tudor · 03-10-2014, 11:06 AM

MORE INFO: Started it up and let it idle and the oil pressure stayed high. Pulled the dipstick and the oil level was about 1/2 way between add and full. Idled quite a while and was fine. Took it for a short spin and when making RIGHT turns, the pressure drops. Left turns, no issue. Obviously the oil is moving away from the pickup and the pump is sucking air. No problems straight ahead or left turns.

Maybe that's why Daytona turns left.....

Bob-A · 03-10-2014, 02:42 PM

Only commies turn left!

I read once that when J. Edgar Hoover was driven to work each morning by his chauffeur. The route to his office had to have no left turns.........

Bob-A

peters180a/170b · 03-10-2014, 03:45 PM

Not a Model "A" Ford but a Ford V10 250, pickup .Starts up on a cold morning around 10- 15 and no oil pressure for about 30-45 seconds and then up goes the pressure. Did this about 5 times this winter. Changed the oil with less then 3000 miles since last changed and no problem now... I am running 5W -20

Paul from Maine · 03-10-2014, 07:44 PM

Quote:

Originally Posted by 29 Tudor

Odd situation. I have a oil pressure gauge and the A-Ford-Able full flow oil filter kit. I run 15W-40 diesel oil. Today when I started the engine, the temperature was probably low 50's. The gauge normally goes past 10 PSI when the engine is cold and settles to around 4 PSI at road speed when hot. Here's the interesting thing... when cold, if I rev the engine just a bit, the pressure drops to zero... stays there for a few seconds ... like maybe 10 or so and then comes back up. All this happens slowly because the oil line to the gauge is so small.

Since it comes back up and since once warm, it stays perfectly normal, I'm trying to figure out what's happening. I wonder if it's possible that the pump is pumping enough of the cold oil into the valve chamber, and the drainback is slow enough, to starve the pump momentarily. I was thinking that the bypass valve in the filter was opening and since the gauge is really reading the restriction of the filter, with the bypass open, the restriction is lower but before I installed the filter kit, I never saw the pressure drop to zero but, the outside temperatures were higher as well.

Clearly the pump is working since the pressure comes back shortly. I WAS running with the oil level about half way between add and full. Might try filling to the full mark and see if it makes a difference.

Anyone else ever seen this and have a theory?

The engine is relatively new and very clean inside.

Thanks in advance for any ideas.

Steve

I wouldn't worry about it because all the pump does is lift oil up to the valve chamber where it flows by gravity to the main bearings. A ten second loss of oil pressure at start up would probably have little or no affect on the volume of oil being supplied to the main bearings if I understand the situation correctly. Some one will correct me if I am wrong!

29 Tudor · 03-10-2014, 07:52 PM

I think you're right Paul. The pressure comes up fine when it's cold and it appears that it's okay until right turns at which time, it seems to disappear for a short time but as you say, unless it's gone for a L O N G time, I don't think it's an issue.

Without the oil pressure gauge, I'd never even know it was happening. I wonder if anyone else with a pressure gauge has tried right and left turns. I went to a local cul-d-sac and tested it.

Thanks for the reply,

Steve

PC/SR · 03-10-2014, 08:08 PM

Momentary loss of pressure on right turn is not uncommon.

29 Tudor · 03-10-2014, 08:11 PM

PC/SR,

Thanks for the confirmation! I suspected it was "normal" because this motor is in like-new shape but it's nice to have it confirmed. With no oil pressure gauge, one would never know!

Thanks!

Steve

Dick So. Cal. · 03-11-2014, 11:10 AM

Before I started my new engine, I installed an oil pressure gauge directly into the side of the engine using the 1/8" pipe opening above the oil pump. My idea was to verify oil pressure at start up. I had 9-10 lbs right away and it dropped to about 2 when warm (normal). The gauge is still there and I check it once in a while, especially after an oil change. I use the 15-40 diesel oil and all is well.

Dick Wyckoff

03-09-2014, 09:47 PM	#1
29 Tudor Senior Member Join Date: Apr 2011 Location: Magnolia, TX Posts: 161	Cold Oil Pressure Drops to Zero, Then Comes Back Odd situation. I have a oil pressure gauge and the A-Ford-Able full flow oil filter kit. I run 15W-40 diesel oil. Today when I started the engine, the temperature was probably low 50's. The gauge normally goes past 10 PSI when the engine is cold and settles to around 4 PSI at road speed when hot. Here's the interesting thing... when cold, if I rev the engine just a bit, the pressure drops to zero... stays there for a few seconds ... like maybe 10 or so and then comes back up. All this happens slowly because the oil line to the gauge is so small. Since it comes back up and since once warm, it stays perfectly normal, I'm trying to figure out what's happening. I wonder if it's possible that the pump is pumping enough of the cold oil into the valve chamber, and the drainback is slow enough, to starve the pump momentarily. I was thinking that the bypass valve in the filter was opening and since the gauge is really reading the restriction of the filter, with the bypass open, the restriction is lower but before I installed the filter kit, I never saw the pressure drop to zero but, the outside temperatures were higher as well. Clearly the pump is working since the pressure comes back shortly. I WAS running with the oil level about half way between add and full. Might try filling to the full mark and see if it makes a difference. Anyone else ever seen this and have a theory? The engine is relatively new and very clean inside. Thanks in advance for any ideas. Steve

03-09-2014, 10:28 PM	#2
29 Tudor Senior Member Join Date: Apr 2011 Location: Magnolia, TX Posts: 161	Re: Cold Oil Pressure Drops to Zero, Then Comes Back Possibly but I wouldn't think that 15W-40 is THAT thick at 50 degrees. I appreciate the thought though.

03-10-2014, 06:41 AM	#3
Bob-A Senior Member Join Date: May 2010 Location: Central FL, USA Posts: 1,137	Re: Cold Oil Pressure Drops to Zero, Then Comes Back 29 Tudor, On my '29 roadster I have pretty much the same exact set-up as you have with the addition of a can of STP in the oil. I've never had the experience you are having, but I've never driven the car in that cold of weather either. Plus, I keep my oil level right at the full mark on the dip stick. Bob-A

03-10-2014, 06:44 AM	#4
QGolden Senior Member Join Date: Sep 2011 Location: Alton, NH Posts: 1,231	Re: Cold Oil Pressure Drops to Zero, Then Comes Back I know very little of the Full Flow Oil Filter Kit, but I did see similiar symptoms once on a 1960's European Import. After a lot of checking, testing, and removing and cleaning the external oil filter kit and changing the filter, the problem went away. We were pretty sure the filter bypass valve was opening while the oil pressure was high, and sticking open for a few seconds. __________________ It's not what people think they know that will hurt them, it is what they think they know that aint so! -Mark Twain. It is the very things that we think we know, that keep us from learning what we should know.- Unknown

03-10-2014, 06:44 AM	#5
Patrick L. Senior Member Join Date: May 2010 Location: Largo Florida Posts: 7,225	Re: Cold Oil Pressure Drops to Zero, Then Comes Back Did this just start to happen? Like maybe after the last oil/filter change ? I think your idea of adding an extra quart to see what happens is a good one.

03-10-2014, 06:53 AM	#6
29 Tudor Senior Member Join Date: Apr 2011 Location: Magnolia, TX Posts: 161	Re: Cold Oil Pressure Drops to Zero, Then Comes Back Sponsored Links (Register now to hide all advertisements) My first thought was the bypass opening as well but as I recall from running just the oil pressure gauge before the filter was instilled, as the engine was warming up, I don't remember the pressure dropping like that. I have tried to find an equivalent to the Ford FL-1 filter that doesn't have a bypass to see if that is the problem but it appears that no one makes a filter with a 3/4-16 thread that doesn't have a bypass. I am going to fill it to the full mark and see if it still happens. As for the oil change, the car was using straight 30 weight and I now run 15W-40. I appreciate all the responses and suggestions. Steve

03-10-2014, 07:52 AM	#7
Dave in MN Senior Member Join Date: May 2010 Location: Jordan, MN Posts: 1,411	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.

03-10-2014, 08:04 AM	#8
29 Tudor Senior Member Join Date: Apr 2011 Location: Magnolia, TX Posts: 161	Re: Cold Oil Pressure Drops to Zero, Then Comes Back Dave, Thanks for the confirmation!! Glad I'm not the only one. There are no strange noises and the engine runs fine. I think I will start it this morning (high 40's) and let it idle a bit and warm up the oil to see what happens. With the screen on the oil pump being as fine as it is, it occurs to me that the pump MIGHT be cavitating from the "high" viscosity but I don't know any way to find out. Since it NEVER does it once the oil warms a bit, like you, I don't think it's a major concern but it sure is disconcerting to look over an see the pressure dropping! I wish I could find a filter with no bypass to eliminate that as a possibility. Thanks for confirming that someone else has seen the same issue!! Steve

03-10-2014, 11:06 AM	#9
29 Tudor Senior Member Join Date: Apr 2011 Location: Magnolia, TX Posts: 161	Re: Cold Oil Pressure Drops to Zero, Then Comes Back MORE INFO: Started it up and let it idle and the oil pressure stayed high. Pulled the dipstick and the oil level was about 1/2 way between add and full. Idled quite a while and was fine. Took it for a short spin and when making RIGHT turns, the pressure drops. Left turns, no issue. Obviously the oil is moving away from the pickup and the pump is sucking air. No problems straight ahead or left turns. Maybe that's why Daytona turns left.....

03-10-2014, 02:42 PM	#10
Bob-A Senior Member Join Date: May 2010 Location: Central FL, USA Posts: 1,137	Re: Cold Oil Pressure Drops to Zero, Then Comes Back Only commies turn left! I read once that when J. Edgar Hoover was driven to work each morning by his chauffeur. The route to his office had to have no left turns......... Bob-A

03-10-2014, 03:45 PM	#11
peters180a/170b Senior Member Join Date: May 2010 Location: Putnam Valley N.Y. Posts: 2,151	Re: Cold Oil Pressure Drops to Zero, Then Comes Back Not a Model "A" Ford but a Ford V10 250, pickup .Starts up on a cold morning around 10- 15 and no oil pressure for about 30-45 seconds and then up goes the pressure. Did this about 5 times this winter. Changed the oil with less then 3000 miles since last changed and no problem now... I am running 5W -20

03-10-2014, 07:52 PM	#13
29 Tudor Senior Member Join Date: Apr 2011 Location: Magnolia, TX Posts: 161	Re: Cold Oil Pressure Drops to Zero, Then Comes Back I think you're right Paul. The pressure comes up fine when it's cold and it appears that it's okay until right turns at which time, it seems to disappear for a short time but as you say, unless it's gone for a L O N G time, I don't think it's an issue. Without the oil pressure gauge, I'd never even know it was happening. I wonder if anyone else with a pressure gauge has tried right and left turns. I went to a local cul-d-sac and tested it. Thanks for the reply, Steve

03-10-2014, 08:08 PM	#14
PC/SR Senior Member Join Date: May 2010 Location: Santa Rosa, CA Posts: 1,279	Re: Cold Oil Pressure Drops to Zero, Then Comes Back Momentary loss of pressure on right turn is not uncommon.

03-10-2014, 08:11 PM	#15
29 Tudor Senior Member Join Date: Apr 2011 Location: Magnolia, TX Posts: 161	Re: Cold Oil Pressure Drops to Zero, Then Comes Back PC/SR, Thanks for the confirmation! I suspected it was "normal" because this motor is in like-new shape but it's nice to have it confirmed. With no oil pressure gauge, one would never know! Thanks! Steve

03-11-2014, 11:10 AM	#16
Dick So. Cal. Senior Member Join Date: May 2010 Location: El Segundo CA Posts: 181	Re: Cold Oil Pressure Drops to Zero, Then Comes Back Before I started my new engine, I installed an oil pressure gauge directly into the side of the engine using the 1/8" pipe opening above the oil pump. My idea was to verify oil pressure at start up. I had 9-10 lbs right away and it dropped to about 2 when warm (normal). The gauge is still there and I check it once in a while, especially after an oil change. I use the 15-40 diesel oil and all is well. Dick Wyckoff