oil pressure gauge backwards - Ford Powerstroke Diesel Forum
Powerstroke.org is the premier Diesel Truck Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 01-05-2012, 03:24 PM
Member
 

Join Date: Nov 2011
Location: navarre ohio
Posts: 57
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
oil pressure gauge backwards

i bought a 94.5 f350 7.3 powerstroke with 140k miles, a few months ago, and have been working on it since.i finally got to go on the first real 50 mile drive sunday. i noticed i have great oil pressure at idle but as soon as i step on it the gauge drops down almost to the low mark. it just had an oil change, and the truck runs great. it doesn't make any sense to me. usually it works the opisite, low pres at idle and high under throttle. is this just a powerstroke thing from the injectors taking oil or?? is this something i should worry about, what is going on..
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 01-05-2012, 07:28 PM
Compression Ignition Addict
 

Join Date: Oct 2011
Location: Tehachapi, CA
Posts: 1,801
Thanks: 0
Thanked 40 Times in 40 Posts
Feedback Score: 0 reviews
In the factory installation, the gauge is really a glorified idiot light. A typical oil pressure sending unit will vary the resistance with oil pressure. The one on our trucks is not a typical sending unit, but only a switch (no varying resistance with pressure) that is OPEN or CLOSED at a threshold pressure (I think about 6 psi). If the pressure is above the threshold, the switch is CLOSED and the guage is supposed to read mid-scale. Folks have modified the setup to use a real sender, but the gauge doesn't range all that much. The switch is on top of the High Pressure Oil Pump (HPOP) reservoir (rectangular box on the top front of the motor under the decorative engine cover). If you disconnect the switch wire and ground it, the guage should read mid-scale. Hope that helps, Cheers!
Reply With Quote Quick reply to this message
  #3  
Old 01-05-2012, 10:35 PM
Member
 

Join Date: Nov 2011
Location: navarre ohio
Posts: 57
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
why would the gauge be mid way at idle, and drop to almost nothing under power?
Reply With Quote Quick reply to this message
  #4  
Old 01-06-2012, 03:22 AM
Member
 

Join Date: Nov 2007
Location: kansas
Posts: 30
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
i have been working on an 02 7.3 and i have a similar question
mine i can watch the oil level in the hpop go down as i crank it i hope some one answers your question
Reply With Quote Quick reply to this message
  #5  
Old 01-06-2012, 08:00 AM
Compression Ignition Addict
 

Join Date: Nov 2011
Location: The great state of Warshington
Posts: 889
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
Protec, I'm curious. Are you visually watching the HPOP drain while you crank somehow? Or are you talking about HPOP pressure decreasing?
Reply With Quote Quick reply to this message
  #6  
Old 01-06-2012, 10:03 AM
Compression Ignition Addict
 

Join Date: Oct 2011
Location: Atlanta
Posts: 207
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
Send a message via Skype™ to OnTheBio
Quote:
Originally Posted by j1mmy View Post
why would the gauge be mid way at idle, and drop to almost nothing under power?
The gauge you're using is a pressure gauge. It's dropping because it's showing low oil pressure because your hpop is failing/can't keep up/needs replaced.

It seems to be that your oil pressure is dropping because you're "getting on it"....

That's normal. Although it should hold a minimal PSI (i think it's 1900?) at all times driving, a certain psi while cranking (I think is 450?), and I believe a max of (4000?).

Someone can correct me if I'm wrong

Does your gauge show numbers or just say low, norm, and hi?

edit - Does anyone know if a low oil amount would cause low oil pressure or would you run into other problems being low on oil first??

Last edited by OnTheBio; 01-06-2012 at 10:07 AM.
Reply With Quote Quick reply to this message
  #7  
Old 01-06-2012, 10:28 AM
Compression Ignition Addict
 

Join Date: Nov 2011
Location: The great state of Warshington
Posts: 889
Thanks: 0
Thanked 1 Time in 1 Post
Feedback Score: 0 reviews
Nope, not a pressure guage. As mentioned earlier, these guages are a glorified idiot light. For the most part they'll run in the 'normal range' until you have a problem (no oil pressure). If you want an actual pressure reading, aftermarket is you're best bet.
Does the needle drop all the way down to red, or just move in that direction?
Also, have you checked the oil level since you changed it? I doubt this has anything to do with it though...as you'd probably notice hard starting before you noticed the oil guage move.
Reply With Quote Quick reply to this message
  #8  
Old 01-06-2012, 12:40 PM
Compression Ignition Addict
 

Join Date: Oct 2011
Location: Tehachapi, CA
Posts: 1,801
Thanks: 0
Thanked 40 Times in 40 Posts
Feedback Score: 0 reviews
I'm not up on the SD's or 2002 models, so maybe they have an actual oil pressure gauge. The OBS trucks do not. The oil pressure gauge is on the LP oil system. If the reservoir is draining during operation, the LP oil pump might be getting weak or there is a cracked pickup tube. Conversly, if the HPOP can't keep up you should get a CEL. As far as the gauge "moving" it could be anything from a bad switch, wiring, or gauge. Try grounding the wire and see what happens. Cheers!
Reply With Quote Quick reply to this message
  #9  
Old 01-19-2012, 10:13 PM
Member
 

Join Date: Nov 2011
Location: navarre ohio
Posts: 57
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
i fixed the gauge.. the sender had a bad connection.. it is still weird how it worked. must of torqued and lost connection under power.. but it is fixed now.. thanks for the help.
\
Reply With Quote Quick reply to this message
  #10  
Old 01-20-2012, 12:35 AM
DERAIL MOD!!!



 

Join Date: May 2011
Location: Canton and kennesaw
Posts: 21,544
Thanks: 19
Thanked 139 Times in 127 Posts
Feedback Score: 4 reviews
Quote:
Originally Posted by Patrick Feeley View Post
In the factory installation, the gauge is really a glorified idiot light. A typical oil pressure sending unit will vary the resistance with oil pressure. The one on our trucks is not a typical sending unit, but only a switch (no varying resistance with pressure) that is OPEN or CLOSED at a threshold pressure (I think about 6 psi). If the pressure is above the threshold, the switch is CLOSED and the guage is supposed to read mid-scale. Folks have modified the setup to use a real sender, but the gauge doesn't range all that much. The switch is on top of the High Pressure Oil Pump (HPOP) reservoir (rectangular box on the top front of the motor under the decorative engine cover). If you disconnect the switch wire and ground it, the guage should read mid-scale. Hope that helps, Cheers!
im interested in how one would make it semi work as a gauge instead of an idiot light
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Ford Powerstroke Diesel Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may 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
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -8. The time now is 09:33 PM.


Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Optimization by vBSEO 3.6.1
Garage Plus, Vendor Tools vBulletin Plugins by Drive Thru Online, Inc.

vB.Sponsors