Go Back   Club Cobra > Club Cobra Tech Areas > Shop Talk

Welcome to Club Cobra!  The World's largest non biased Shelby Cobra related site!

  •  » Representation from nearly all Cobra/Daytona/GT40 manufacturers
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and nearly 1 million posts! 

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

Nevada Classics
MMG Superformance
Main Menu
Nevada Classics
Nevada Classics
MMG Superformance
Advertise at CC
Banner Ad Rates
Keith Craft Racing
Keith Craft Racing
MMG Superformance
August 2022
  1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30 31      
  #1 (permalink)  
Old 03-29-2006, 06:22 PM
CC Member
Visit my Photo Gallery

Join Date: Apr 2005
Location: Near Chattanooga, TN
Cobra Make, Engine: SPF, 418 Stroker
Posts: 220
Not Ranked     
Default Effects of Stuck Oil Pump Relief Valve

Could some of you engine experts please check out my understanding of the effects of a stuck oil pump relief valve :
1. A relief valve stuck in the fully closed position may result in very high oil pressure.
2. A relief valve stuck in the fully open position will result in little or no oil pressure, since the pump flow is dumped immediately back to the sump.
3. Now the most interesting one: A relief valve that is stuck in an intermediate position that blocks part of the relief port can result in reduced, but still acceptable oil pressure. In this scenario, the partially open port acts like a small leak, but the pump is able to handle that "leak" and still supply adequate oil to the bearings, etc.
Right, wrong, somewhere in between? Thanks.
Jerry aka CWizard
Reply With Quote
Sponsored Links
Sponsored Links
  #2 (permalink)  
Old 03-29-2006, 06:28 PM
CC Member
Visit my Photo Gallery

Join Date: Jun 2004
Location: Christchurch, NZ
Cobra Make, Engine: Ram 427 SC CSX6042. Chev 355. Quad Weber DCNFs
Posts: 208
Send a message via ICQ to mylesdw
Not Ranked     

I reckon the partially open case would result in very low oil pressure at low revs but at a certain rpm the pressure would recover and look more normal. It would really depend how 'open' it was.
Myles D-W
Reply With Quote
  #3 (permalink)  
Old 03-29-2006, 07:57 PM
Rick Parker's Avatar
CC Member
Visit my Photo Gallery

Join Date: May 2001
Location: California, Ca
Cobra Make, Engine: NAF 289 Slabside Early Comp Car with 289 Webers and all the goodies. Cancelling the efforts of several Priuses
Posts: 6,592
Not Ranked     

If there was a piece of foreign material blocking it, or if the bypass valve is shimmed too much, thus preventing the bypass plunger from opening, the consequence would be unlimited high end pressure. It can reach the point of potentially popping the crimped seal on even a High Performance oil filter such as FL-1HP. I have had this happen, it's exciting and makes a BIG mess. POW!
However too answer your question, YES you would have pressue but it would be very unstable even though the gauge may indicate otherwise. It is like a huge internal leak. It may also tend to aireate the oil considerably. Fix it.

As you slide down the Banister of Life, may the splinters never be pointing the wrong way

Last edited by Rick Parker; 03-29-2006 at 08:02 PM..
Reply With Quote

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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -7. The time now is 12:58 AM.

Powered by vBulletin® Version 3.8.0
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
The representations expressed are the representations and opinions of the forum members and do not necessarily reflect the opinions and viewpoints of the site owners, moderators, Shelby American, any other replica manufacturer, Ford Motor Company. This website has been planned and developed by and its forum members and should not be construed as being endorsed by Ford Motor Company, or Shelby American or any other manufacturer unless expressly noted by that entity. "Cobra" and the Cobra logo are registered trademarks for Ford Motor Co., Inc. forum members agree not to post any copyrighted material unless the copyrighted material is owned by you. Although we do not and cannot review the messages posted and are not responsible for the content of any of these messages, we reserve the right to delete any message for any reason whatsoever. You remain solely responsible for the content of your messages, and you agree to indemnify and hold us harmless with respect to any claim based upon transmission of your message(s). Thank you for visiting For full policy documentation refer to the following link: CC Policy