Oil pressure problem after oil change


33Bravo

GT Owner
Mark II Lifetime
Nov 3, 2006
688
Minneapolis, MN
Anybody ever teach you guys to label axes?

Here
 

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fjpikul

GT Owner
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Jan 4, 2006
11,674
Belleville, IL
Good one bud. I was hoping to shame the author.
 

nota4re

GT Owner
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Feb 15, 2006
4,279
Good one bud. I was hoping to shame the author.

...but 33Bravo succeeded.
 

Indy GT

Yea, I got one...too
Mark IV Lifetime
Jan 14, 2006
2,545
Greenwood, IN
Justin,

Here is a plot of some data that I took last year. It gives you an idea of the expected gauge reading once the motor is at a normal operating temperature.

Good luck, Jay

Jay, we LOVE data!!!:thumbsup

But in this instance, Dr. Frank is correct about labeled axes.:facepalm:
 

analogdesigner

GT Owner
Mark IV Lifetime
Nov 15, 2005
950
San Clemente, CA USA
Updated oil pressure sender chart

Oh you guys are tough! So I had to figure out how to add axis labels in Excel 2007. 2003 was much easier to use! I also removed some of the statistical outliers.

Jay

Ford GT oil pressure sender chart.gif
 
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fjpikul

GT Owner
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Le Mans 2010 Supporter
Jan 4, 2006
11,674
Belleville, IL
Thank you Analog. Looking at graphs and charts all the time just makes it that much easier
 

Justin

GT Owner
Jun 30, 2013
27
Massachusetts
Thanks for the graph! I have my new gauge in hand (thanks again Northwood), soon as I get home the install will commence and we will see... Hopefully everything is solved.
 

Indy GT

Yea, I got one...too
Mark IV Lifetime
Jan 14, 2006
2,545
Greenwood, IN
VERY nice Jay!
Thanks for being a good sport about the ribbing..
 

Justin

GT Owner
Jun 30, 2013
27
Massachusetts
Unfortunately the issue still remains. After a gauge replacement and sending unit replacement I still have the issue. Basically the oil,pressure goes to 25-30 at start up, at revving it goes to 55-60 max. As soon as i drive it, then come to a stop, it drops to zero. If i touch the gas it pops right back to 25. Everything was fine until an oil change. I guess i'm at a crossroads as to whether to bring it back to the dealer. Unfortunately there just arent many people who know this car well that are local.
 

TO AWSUM

Ford GT Owner
Mark II Lifetime
Jul 4, 2007
1,512
Niceville FL
Since it started after the oil change, I was thinking (dangerous thing I know) and was wondering if you used the copper washer that comes with the filter? Don't use the washer. Also when you place the new filter in the housing, firmly press it into the housing until you feel it click a couple times. Other than this, its got to be the pump itself or the pulley slipping.

Sent from my SM-N920V using Tapatalk
 

CJ428

Farm GT
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May 21, 2008
1,475
NJ
yea I would take the filter out and check it first if everything is correct then it must be the belt or pulley.
 

Justin

GT Owner
Jun 30, 2013
27
Massachusetts
Yeah the dealer did the oil change so I could bring it back to them to check the filter. Im not sure obviously as to what they did. I would think they would have seen the belt and pully during the pressure sender change they did over the 5 days the had it lol. Is the belt and pully easily visible when the belly pan is dropped?
 

Xcentric

GT Owner
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Jul 9, 2012
5,213
Myakka City, Florida
Yeah the dealer did the oil change so I could bring it back to them to check the filter. Im not sure obviously as to what they did. I would think they would have seen the belt and pully during the pressure sender change they did over the 5 days the had it lol. Is the belt and pully easily visible when the belly pan is dropped?
Not likely a filter problem. Even if the filter is crushed, clogged, or otherwise inoperative, a bypass valve will allow full oil pressure to the engine.

I guess the bypass valve could malfunction, but never heard of this. It's like a failsafe device.

Oil pump belt and pulley are under a cover. Not visible.
 

CJ428

Farm GT
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May 21, 2008
1,475
NJ
seems really odd all this stared when they changed the oil.
 

TO AWSUM

Ford GT Owner
Mark II Lifetime
Jul 4, 2007
1,512
Niceville FL
seems really odd all this stared when they changed the oil.

Agree so what changed? - the oil and filter. Doubt the oil would cause a change, so that leaves the filter.

Maybe it was just an oversight and the low oil readings just weren't noticed until the oil change which drew the owners attention to the oil gauge. Low oil pressure might have been present before the oil change but the owner didn't look at the gauge.
 
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CJ428

Farm GT
Mark II Lifetime
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May 21, 2008
1,475
NJ
if you were closer Justin I would say to get it on the lift in the shop and we would get to the bottom of this. Cant understand why your Ford tech wouldn't have checked the pump already.
 

nota4re

GT Owner
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Feb 15, 2006
4,279
I say that the odds are that you just purchased another bad gauge.....
 

Justin

GT Owner
Jun 30, 2013
27
Massachusetts
definitely not a problem prior to oil change. This spring saw two gauges die when my battery died during the winter storage (even though it was on a charger) so the oil gauge was new this April from autometer. I'm pretty detail oriented and oil pressure has never been an issue let alone going to zero causing the dummy light to come on. As far as a second gauge being bad... the gauge is showing the exact same pattern. Doubtful. i'd be more inclined to think its the sender thats bad twice, but, the pattern is so exactly replicated after changing the gauge and sender, i have to believe there is another cause. I think the Ford tech relied on the mechanical gauge to feel there is no issue with the pump or actual pressure, but im seeing reasonable pressure on the gauge until I drive a bit. They just checked pressure on the lift and said it went to 'like 60 pounds at higher rpm' so that was enough for them to feel its a sender issue. So yeah, its a head scratcher.
 

Spirit

Heritage GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
You may want to check the oil filter itself.
1. Was the correct filter used?
2. Was the filter seated correctly - snapped into place on the filter housing cover?
 

Justin

GT Owner
Jun 30, 2013
27
Massachusetts
Yes, that is going to be my next try. In doing a forum search, it seems that others have had a similar problem- almost exactly the same- oil pressure dropping to zero at idle after oil change. For most there appeared to be no resolution- i.e., it just went away. Of course some had gauge failure, some had sending unit failure. But those were sort of random occurrences or due to a battery failure. There are a few that mirror my issue- oil change followed by low pressure. So I'm going to try another filter and do it myself.