Go Back   The Ford Barn > General Discussion > Late V8 (1954+)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 12-02-2021, 04:28 PM   #1
MCB-12NAM
Junior Member
 
Join Date: Sep 2020
Posts: 19
Default PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

F150 W/ 3.7 liter V6. Once the engine has been running for 10 - 15 minutes (whether idling or under load), the pressure gauge bottoms out and the engine oil warning symbol and alarm go off as soon as the RPM's drop below 1000. As soon as the RPM's are brought back to over 1000 RPM, the gauge bounces right back to the normal range. The top and bottom ends sound fine. idles fine, starts fine, acceleration spot on, the oil level is spot on, the engine temperature is consistently in the normal range and no problem whatsoever cruising at the speed limit on the interstate. What might be causing this?
MCB-12NAM is offline   Reply With Quote
Old 12-02-2021, 06:10 PM   #2
KULTULZ
Senior Member
 
Join Date: Aug 2012
Posts: 4,224
Question Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

Quote:
Originally Posted by MCB-12NAM View Post

F150 W/ 3.7 liter V6.
Year?
KULTULZ is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 12-03-2021, 06:19 AM   #3
MCB-12NAM
Junior Member
 
Join Date: Sep 2020
Posts: 19
Default Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

2014
MCB-12NAM is offline   Reply With Quote
Old 12-03-2021, 11:11 AM   #4
KULTULZ
Senior Member
 
Join Date: Aug 2012
Posts: 4,224
Default Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

It seems FORD is having trouble with the OIL PRESSURE SENDING UNIT.

Go Here - https://www.consumerreports.org/car-...-tsb-for-free/

And enter your VIN to see if any RECALL and/or TSB INFO.

Does the MIL (Check Engine Light) illuminate at any point?

Get back.
KULTULZ is offline   Reply With Quote
Old 12-03-2021, 04:54 PM   #5
MCB-12NAM
Junior Member
 
Join Date: Sep 2020
Posts: 19
Default Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

No recalls, no TSB's and Check Engine Light does not illuminate.
MCB-12NAM is offline   Reply With Quote
Old 12-03-2021, 05:59 PM   #6
cadillac512
Senior Member
 
cadillac512's Avatar
 
Join Date: Apr 2019
Location: Kansas
Posts: 338
Default Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

Sponsored Links (Register now to hide all advertisements)
99.9% chance it's the sending unit as KULTULZ advised.
__________________
"It don't take but country smarts to solve the problem" (Smokey Yunick)


'41 Merc Town Sedan / 260" 8CM engine
cadillac512 is offline   Reply With Quote
Old 12-03-2021, 07:06 PM   #7
KULTULZ
Senior Member
 
Join Date: Aug 2012
Posts: 4,224
Thumbs up Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

Yeah, because it is tied to the PCM (POWER-TRAIN CONTROL MODULE). It will stop the engine if it doesn't see correct oil pressure.

If you GOOGLE the year truck/engine and the problem, you will find a bunch of info.
KULTULZ is offline   Reply With Quote
Old 12-05-2021, 10:26 AM   #8
MCB-12NAM
Junior Member
 
Join Date: Sep 2020
Posts: 19
Default Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

Will be replacing the sending unit. Found it just below and back of the alternator. As luck would have it, can easily reach it from the top. Googled as suggested. One mentioned this all started just after he changed the oil. Bingo! Same here ! ! ! Coincidence? Who knows. Wonder if some crud got stirred up and found its way to the sending unit when I changed the oil. Not likely anything I did wrong when I changed the oil & filter as I am OCD about that stuff and have been changing same since the 60's (first one was on an early 50's Willys flat head). Thanks go out to KULTULZ and Cadillac 512 for taking the time and interest to point me in the right direction. PS, totally agree with your stated philosophies - good old common sense and being a straight shooter are two of man's best friends in life!
MCB-12NAM is offline   Reply With Quote
Old 12-05-2021, 10:49 AM   #9
KULTULZ
Senior Member
 
Join Date: Aug 2012
Posts: 4,224
Thumbs up Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

Make sure it is a MOTORCRAFT switch as aftermarket has been giving trouble.

Also, read in your research about oil pressure failure in this engine series.
KULTULZ is offline   Reply With Quote
Old 12-05-2021, 12:10 PM   #10
KULTULZ
Senior Member
 
Join Date: Aug 2012
Posts: 4,224
Exclamation Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

- FORGOT -

Make sure the connector has no oil due to the sensor leaking. Also check the harness to see if oil wicked up it. Use electric contact cleaner to remove any oil.
KULTULZ is offline   Reply With Quote
Old 12-06-2021, 12:20 PM   #11
MCB-12NAM
Junior Member
 
Join Date: Sep 2020
Posts: 19
Default Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

Quote:
Originally Posted by KULTULZ View Post
Make sure it is a MOTORCRAFT switch as aftermarket has been giving trouble.

Also, read in your research about oil pressure failure in this engine series.
Will do. Thanks!
MCB-12NAM is offline   Reply With Quote
Old 12-06-2021, 12:20 PM   #12
MCB-12NAM
Junior Member
 
Join Date: Sep 2020
Posts: 19
Default Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

Will do. Thanks!
MCB-12NAM is offline   Reply With Quote
Old 12-10-2021, 02:23 PM   #13
MCB-12NAM
Junior Member
 
Join Date: Sep 2020
Posts: 19
Default Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

Follow up:

Disconnected the negative battery cable.
Disconnected the electrical terminal connector to the old sensor (sqeeze & pull).
Disconnected (7/16" socket) the battery cable from the alternator and swung out of the
way to gain room to get the old sensor out.
Spun out (13/16" socket to start & then 13/16" open end) the old sensor.
Couple of applications of electrical contact cleaner to the electrical terminal connector.
(found oily when removed due the old sensor leaking oil). (this also explained some
oil loss that I had started experiencing but could not figure out where).
Installed the new sensor being careful not to over torque and orientating so that the
the side of the sensor where the depressed plastic snaps in matched the "lay" of the
terminal connection (to avoid unnecessary bending of the light gauge wire). Did not
need to ad Teflon tape as the threads already had Teflon applied).
Applied a dab of dielectric compound to the electrical connection and snapped into
place.
Reconnected the alternator battery cable (gave that a light sqirt of cleaner for good
measure also before reconnecting).
As long as the neg cable was already off the battery, removed the positive cable also,
cleaned the battery posts, cable ends, reconnected & sprayed both with battery
corrosion inhibitor.
Started the engine, checked for leaks and checked the oil pressure gauge both at idle
and after running under load for awile. So far so good!

Thanks go out again to KULTULZ and CADILLAC 152 for solving the mystery and pointing me in the right direction.
MCB-12NAM is offline   Reply With Quote
Old 12-10-2021, 02:44 PM   #14
KULTULZ
Senior Member
 
Join Date: Aug 2012
Posts: 4,224
Thumbs up Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

Quote:
Started the engine, checked for leaks and checked the oil pressure gauge both at idle and after running under load for awile. So far so good!
Don't forget now that when the BAT CABLE(S) are removed, the PCM looses some of its memory, including some drive-ability parameters ( another college word). It may take a little driving for the PCM to re-learn its fuel curve and especially trans shift functions. So if it acts a little strange for a while you know what it most likely is.

Keep an eye on the MIL.
KULTULZ is offline   Reply With Quote
Old 12-11-2021, 04:17 PM   #15
cadillac512
Senior Member
 
cadillac512's Avatar
 
Join Date: Apr 2019
Location: Kansas
Posts: 338
Default Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

That's great. Good job!
__________________
"It don't take but country smarts to solve the problem" (Smokey Yunick)


'41 Merc Town Sedan / 260" 8CM engine
cadillac512 is offline   Reply With Quote
Old 12-14-2021, 09:38 AM   #16
MCB-12NAM
Junior Member
 
Join Date: Sep 2020
Posts: 19
Default Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

KULTULZ and CADILLAC 512 - Many thanks for the good words and yes, I did notice some "out of character" shifting going on initially but that has pretty well worked itself out. After
dealing with that dog gone dinging buzzer going off constantly, what a pleasure to drive now without that irritant! BTW, forget to mention in the "follow up" that I did use a Motorcraft sensor as suggested.
MCB-12NAM is offline   Reply With Quote
Old 12-14-2021, 11:00 AM   #17
KULTULZ
Senior Member
 
Join Date: Aug 2012
Posts: 4,224
Thumbs up Re: PRESSURE GAUGE ABRUPTLY BOTTOMS OUT BELOW 1000 rpm

Quote:
BTW, forget to mention in the "follow up" that I did use a Motorcraft sensor as suggested.
Forgot to mention, you needn't buy MOTORCRAFT (or P&A) from a local dealer. You can purchase from ONLINE DEALERS, AMAZON and such at a discount.

Here's One - https://k-mansparts.com/

Just One Online Dealer - https://www.tascaparts.com/v-ford
KULTULZ is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 03:34 AM.