Welcome to Club Hot Rod!  The premier site for everything to do with Hot Rod, Customs, Low Riders, Rat Rods, and more. 

  •  » Members from all over the US and the world!
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and hundreds of thousands of posts! 

YES! I want to register an account for free right now!  p.s.: For registered members this ad will NOT show

 
Like Tree9Likes

Thread: 7.5 professional rebuild 15K miles no oil pressure at hot idle
          
   
   

Reply To Thread
Page 1 of 2 1 2 LastLast
Results 1 to 15 of 24
  1. #1
    twolaneblacktop is offline CHR Member Visit my Photo Gallery
    Join Date
    Nov 2010
    Location
    lebanon
    Car Year, Make, Model: 65 Nova big tire car 73 Nova big block
    Posts
    44

    7.5 professional rebuild 15K miles no oil pressure at hot idle

     



    Hi guys,
    I need your opinions on this one. I had a 95 7.5 out of my F250 totally gone through at a professional shop. No corners cut. After I put it back in I changed oil every 1K to 3K miles and used Shell Rotella oil. Runs great. Around 15K miles I noticed that I had 0 oil PSI at idle with a hot engine. Changed sending unit and oil/filter. Still 0 PSI at hot idle. Checked with a mechanical gage 0 PSI at hot idle. Now the part that drives me nuts. 1K rpm and the same great PSI as when just rebuilt. Bring RPM up to 1K and the gage snaps right up to 60 PSI.
    What do you all think?
    I should also say that when the thing drops to 0 PSI there is no valve noise no difference in sound what so ever.
    Last edited by twolaneblacktop; 02-13-2016 at 07:52 PM.

  2. #2
    rspears's Avatar
    rspears is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Sep 2007
    Location
    Gardner, KS
    Car Year, Make, Model: '33 HiBoy Coupe, '32 HiBoy Roadster
    Posts
    11,124

    Ford Truck forums point to the stock oil pressure guages after '87 being glorified idiot lights with a pressure switch sending unit. Once above a set point minimum the gauge reads mid-range, but has zero analog accuracy. If pressure is below set point the gauge reads zero, and if it's above minimum it reads mid-range, which seems to be 60psig for yours.
    techinspector1 likes this.
    Roger
    Enjoy the little things in life, and you may look back one day and realize that they were really the BIG things.

  3. #3
    firebird77clone's Avatar
    firebird77clone is offline CHR Member Visit my Photo Gallery
    Join Date
    Sep 2005
    Location
    Hamilton
    Car Year, Make, Model: 69 nomad, 73 charger, 74 vega
    Posts
    3,900

    Just for diagnostic purpose, pull the sending unit and hook up a mechanical guage. No need for a full installation in dash and everything, just be sure the tubing and gauge are safe from fan belts and exhaust and such, and see what readings you get.
    techinspector1 likes this.
    .
    Education is expensive. Keep that in mind, and you'll never be terribly upset when a project goes awry.
    EG

  4. #4
    36 sedan's Avatar
    36 sedan is offline CHR Member Visit my Photo Gallery
    Join Date
    Apr 2012
    Location
    american canyon
    Car Year, Make, Model: 36 Ford Sedan, 23 T Bucket
    Posts
    1,899

    Quote Originally Posted by twolaneblacktop View Post
    Changed sending unit and oil/filter. Still 0 PSI at hot idle. Checked with a mechanical gage 0 PSI at hot idle.
    Something may be stuck in your oil pump's bypass.
    rspears likes this.

  5. #5
    twolaneblacktop is offline CHR Member Visit my Photo Gallery
    Join Date
    Nov 2010
    Location
    lebanon
    Car Year, Make, Model: 65 Nova big tire car 73 Nova big block
    Posts
    44

    I had a cam wipe out in the Ford replacement engine that was originally in the truck when I bought it. One reason I bought it was that NEW dealer installed engine. swapped out the cam and could not get the engine cleaned up by oil changes or Rislone. Spun a rod one day after. That is why I put this fresh rebuild in. Built by reputable shop in Beavercreek Ohio.

  6. #6
    36 sedan's Avatar
    36 sedan is offline CHR Member Visit my Photo Gallery
    Join Date
    Apr 2012
    Location
    american canyon
    Car Year, Make, Model: 36 Ford Sedan, 23 T Bucket
    Posts
    1,899

    IMHO, I would not run the motor until I found the reason for the zero pressure at idle. The first thing I would do is examine the oil and cut the filter open, looking for particles. If nothing in the oil, it could be a broken or jammed bypass spring in the oil pump or clogged oil pump pickup tube screen.
    BTW, I've heard the formula has changed for Rotella oil and may no longer have enough zinc additive to protect a flat tappet cam.

  7. #7
    shine's Avatar
    shine is offline CHR Member Visit my Photo Gallery
    Join Date
    Nov 2003
    Location
    bluff dale texas
    Car Year, Make, Model: 47 inderweed
    Posts
    2,126

    if your getting a 0 reading with the mechanical then i think 36 sedan is right. it is in the oil pump. can it idle for an extended time with no oiling issues ?
    36 sedan likes this.

  8. #8
    twolaneblacktop is offline CHR Member Visit my Photo Gallery
    Join Date
    Nov 2010
    Location
    lebanon
    Car Year, Make, Model: 65 Nova big tire car 73 Nova big block
    Posts
    44

    I have heard about 460 oil pumps mounting boss cracking. Maybe that is the issue. Engine has a new Melling pump but it doesn't have a beefed up mounting boss like some do. Thanks for the Ford oil gage info. That is why the gage goes from zero to the same level each time. Sorry but the only way I can describe my feelings about this fake gage is Rat Bastards. There is still an issue just a different way to think about it. Looks like a tear down is in order. I was afraid that maybe I wiped out a second cam but there is no valve noise. If the cam was gone there would be valve noise all the time.

  9. #9
    twolaneblacktop is offline CHR Member Visit my Photo Gallery
    Join Date
    Nov 2010
    Location
    lebanon
    Car Year, Make, Model: 65 Nova big tire car 73 Nova big block
    Posts
    44

    God I hope not. If that is the case I may have done in another cam.

  10. #10
    36 sedan's Avatar
    36 sedan is offline CHR Member Visit my Photo Gallery
    Join Date
    Apr 2012
    Location
    american canyon
    Car Year, Make, Model: 36 Ford Sedan, 23 T Bucket
    Posts
    1,899

    Quote Originally Posted by twolaneblacktop View Post
    God I hope not. If that is the case I may have done in another cam.
    Don't jump to conclusions to fast, check the oil and oil filter for metal particles first. It may just need the pan removed and the pump repaired.

  11. #11
    NTFDAY's Avatar
    NTFDAY is offline CHR Member Visit my Photo Gallery
    Join Date
    Aug 2003
    Location
    Springfield
    Car Year, Make, Model: '66 Mustang, 76 Corvette
    Posts
    5,370

    Quote Originally Posted by twolaneblacktop View Post
    If the cam was gone there would be valve noise all the time.

    Not necessarily so, I wiped a couple of lobes in a 400 sbc and I don't remember valve train noise, just extremely low on power. BTW, I lived in Lebanon until I was 8 years old and my dad, in the early 40's, was the night manager at the Golden Lamb.
    36 sedan likes this.
    Ken Thomas
    NoT FaDe AwaY and the music didn't die
    The simplest road is usually the last one sought
    Wild Willie & AA/FA's The greatest show in drag racing

  12. #12
    rspears's Avatar
    rspears is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Sep 2007
    Location
    Gardner, KS
    Car Year, Make, Model: '33 HiBoy Coupe, '32 HiBoy Roadster
    Posts
    11,124

    Quote Originally Posted by 36 sedan View Post
    BTW, I've heard the formula has changed for Rotella oil and may no longer have enough zinc additive to protect a flat tappet cam.
    I believe that's true. New regulations on diesel emissions led to a drop in ZDDP in Rotella's oils a year or three back. If I were running a flat tappet cam I'd spring for Brad Penn's oil. Some say that once you've got a good break in that any major oil is OK, but I'd say that's playing Russian Roulette with your engine - at what point is it going to fail?
    NTFDAY and 36 sedan like this.
    Roger
    Enjoy the little things in life, and you may look back one day and realize that they were really the BIG things.

  13. #13
    36 sedan's Avatar
    36 sedan is offline CHR Member Visit my Photo Gallery
    Join Date
    Apr 2012
    Location
    american canyon
    Car Year, Make, Model: 36 Ford Sedan, 23 T Bucket
    Posts
    1,899

    Ive also heard that newer synthetic oils are not good in older designed motors as it is too slick and thin for their bearing designs and doesn't hold oil pressure well in them.

  14. #14
    twolaneblacktop is offline CHR Member Visit my Photo Gallery
    Join Date
    Nov 2010
    Location
    lebanon
    Car Year, Make, Model: 65 Nova big tire car 73 Nova big block
    Posts
    44

    Small world! Lebanon is a nice place today. Jazz and country music festivals in the streets in the summer. Santa comes to town in a Christmas horse drawn carriage parade in December.
    Got to get my truck fixed. I can't get my Camaro to the strip with out it.
    36 sedan likes this.

  15. #15
    twolaneblacktop is offline CHR Member Visit my Photo Gallery
    Join Date
    Nov 2010
    Location
    lebanon
    Car Year, Make, Model: 65 Nova big tire car 73 Nova big block
    Posts
    44

    no synthetic here. I made that mistake before. Flat tappet engines do not do well with that stuff even after break in. I think that is what happened to the Ford replacement engine that was in the truck when I bought it.

Reply To Thread
Page 1 of 2 1 2 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Links monetized by VigLink