The Hull Truth - Boating and Fishing Forum

Go Back   The Hull Truth - Boating and Fishing Forum > BOATING FORUMS > Trucks & Trailers
Search

Notices

Random Quote: yea who belives in fortune cookie belives in everything
Reply
 
Thread Tools Search this Thread
Old 01-09-2011, 11:21 AM
  #1    
Senior Member
 
Join Date: Mar 2010
Location: Dauphin Island, AL
Posts: 1,541
Default 2008 Suburban oil pressure gauge fluctuating.

What would cause the oil pressure gauge to fluctuate from 30 at idle to almost 60 when I'm in the gas? We just bought the truck and have put under 1000 miles on it. The dealership changed the oil before we bought it. Level on dipstick is just a little above full.
__________________
Uncle Sam's favorite nephew!
DLG4354 is offline   Reply With Quote
Old 01-09-2011, 12:16 PM
  #2    
Senior MemberCaptains Club Member
 
Join Date: Nov 2003
Location: San Diego
Posts: 4,691
Default

Check the oil pressure sending switch on the block. Usually the culprit. Maybe warranty.
__________________
"a doughnut is only one step above a rent rod"
doughnut is offline   Reply With Quote
 
Old 01-09-2011, 01:26 PM
  #3    
KJS
Senior MemberCaptains Club MemberPLEDGER
 
Join Date: Aug 2003
Location: Where I go, there I am
Posts: 15,705
Default

Agreed. The oil pressure gauge on our Suburban has been broken for some time.
KJS is offline   Reply With Quote
Old 01-09-2011, 01:30 PM
  #4    
Senior Member
 
Join Date: Dec 2008
Location: Michigan
Posts: 170
Default

Your oil pump is driven by the engine. Higher RPM's mean higher oil pressures. 60 psi is a little high. Perhaps the 'new' oil is not the correct viscosity.

Last edited by Duma Key; 01-09-2011 at 01:31 PM. Reason: duplicate word
Duma Key is offline   Reply With Quote
Old 01-09-2011, 01:33 PM
  #5    
Senior MemberCaptains Club Member
 
Join Date: Nov 2003
Location: San Diego
Posts: 4,691
Default

Quote:
Originally Posted by Duma Key View Post
Your oil pump is driven by the engine. Higher RPM's mean higher oil pressures. 60 psi is a little high. Perhaps the 'new' oil is not the correct viscosity.

Good point. I think clarification is in order. Are you saying the needle swings, or that the oil pressure climbs as you accelerate? If the needle has quick swings, check the sender. If the needle moves smoothly up, and backs off as you reach operating temp. ( oil thins) it is normal.
__________________
"a doughnut is only one step above a rent rod"
doughnut is offline   Reply With Quote
Old 01-09-2011, 03:14 PM
  #6    
Senior Member
 
Join Date: Mar 2010
Location: Dauphin Island, AL
Posts: 1,541
Default

A good way to illustrate it would be to say that the oil pr. gauge mimmics the tach. (low rpms=low pressure. High rpms=high pressure).
__________________
Uncle Sam's favorite nephew!
DLG4354 is offline   Reply With Quote
Old 01-09-2011, 03:29 PM
  #7    
Admirals Club
 
Join Date: May 2008
Location: Between Richmond and Williamsburg
Posts: 2,610
Default

Quote:
Originally Posted by DLG4354 View Post
A good way to illustrate it would be to say that the oil pr. gauge mimmics the tach. (low rpms=low pressure. High rpms=high pressure).
This is fairly normal.
twobyfour is offline   Reply With Quote
Old 01-09-2011, 03:46 PM
  #8    
MemberCaptains Club Member
 
Join Date: Apr 2008
Location: Siesta Key, Fl. Columbus Oh
Posts: 93
Default

My experience with these motors is that as they age the oil pressure varies more. Lower at idle, higher at higher RPM. 30 seems a little low. Should be pretty high when you start the engine cold...
__________________
2000 Pursuit 2470 CC 225 Yami SWSII
2005 Yamaha sx240 sold. Worst boat ever.
1992 sea ray 290 Sundancer sold
1995 cobalt 190. Sold
cjudge is offline   Reply With Quote
Old 01-09-2011, 04:09 PM
  #9    
Senior Member
 
Join Date: Nov 2008
Location: Somewhere in the middle of Michigan
Posts: 6,152
Default

That sounds like what I saw on my '95 5.7L and '04 5.3L.
yarcraft91 is offline   Reply With Quote
Old 01-09-2011, 04:46 PM
  #10    
Senior Member
 
Join Date: Mar 2010
Location: Dauphin Island, AL
Posts: 1,541
Default

This is an '08 5.3 with 30k miles.
__________________
Uncle Sam's favorite nephew!
DLG4354 is offline   Reply With Quote
Old 01-09-2011, 04:54 PM
  #11    
Senior MemberCaptains Club Member
 
Join Date: Feb 2007
Location: MA
Posts: 4,339
Default

Sounds normal.
__________________
'05 Pacific 1925
MacCTD is offline   Reply With Quote
Old 01-10-2011, 06:03 AM
  #12    
Senior Member
 
Join Date: Jan 2006
Location: Sunny florida
Posts: 11,708
Default

It IS normal. ALL engines have lower oil pressure at idle. All you need is 10#'s/1000 rpms. Engines with VTEC or VVT have an oil pressure operated mechanism that can cause momentary pressure fluctuations.

This is why Detroit went to warning lights, and some Fords have a "gauge" that always reads normal..people obsess about oil pressure. After decades of screwing with engines, oil pressure has become a non-issue for me. As long as the engine has some pressure, you're good to go.
billinstuart is offline   Reply With Quote
Old 01-10-2011, 10:22 AM
  #13    
Senior MemberCaptains Club Member
 
Join Date: Nov 2003
Location: San Diego
Posts: 4,691
Default

It should not fluctuate as wildly as the tach. It should be higher when you cold start in the morning at idle, get higher as you accelerate, when you reach operating temp, it should be lower at idle.
__________________
"a doughnut is only one step above a rent rod"
doughnut is offline   Reply With Quote
Old 01-10-2011, 12:26 PM
  #14    
Senior Member
 
Join Date: May 2010
Posts: 180
Default

My '03 Silverado Z71 has the same problem. My mechanic told me it was an electrical issue with the gauge and my pressure is fine.

I already had the gauge cluster fixed about 20,000 miles ago when it went completely out (everything - gas, tach, speedo). I'm not too worried about the oil pressure anymore as I am used to it. If your vehicle is under warranty, the dealership should take care of it.
that_guy is offline   Reply With Quote
Old 01-10-2011, 02:14 PM
  #15    
Senior Member
 
Join Date: Oct 2010
Location: Pensacola
Posts: 2,042
Default

Chevy small blocks were/are equipped with oil pressure relief bypass in the oil pump.
Normal service tops out at 60psi with excess pressure dumped back into oil pan.

Not sure, but I would expect current engines to be equipped the same.
DoubleO7 is offline   Reply With Quote
Old 01-11-2011, 01:48 PM
  #16    
Junior Member
 
Join Date: Nov 2010
Location: Anthem, Az
Posts: 19
Default

I'll post this as just yesterday my gas gauge went south on my '05 Sierra. It literally points down. As someone mentioned above, it's a known problem with a number of GM instrument clusters.

jGm instrument cluster problem

The website is an advertisement, but it does specifically list what vehicles have a known problem by GM. FWIW.

Edit-IMO your oil pressure gauge is normal, as mine always does what yours does...

Last edited by D. Newland; 01-11-2011 at 04:15 PM.
D. Newland is offline   Reply With Quote
Old 01-11-2011, 03:16 PM
  #17    
Senior Member
 
Join Date: Sep 2005
Location: ZEPHYRHILLS FL
Posts: 969
Default

Cluster problems seem to affect the 03-05 trucks the most, haven't heard of many problems wit hthe 07.5+ clusters with failed servo's. As for the oil pressure guage, GM DOES use basically an idiot guage. It reads at one spot at idle, another at cruise, and another when the RPM's go up when you get on it. they went to this style back in 03 for the most part, and again in 06 or so they went to the 3 position style. The only way to really know what the oil pressure is to either put a mechanical guage on it, or to hook up a scanner and see what the oil pressure sensor(yes sensor, not sender anymore) is telling the ECM. This is why the temp guage stays so constant at one point anymore, oil pressure stays so constant, and voltage just seems to be steady all the time for the most part. FORD went another route and made the oil pressure guage read either normal at anything over about 7 PSI, or nothing when it drops below. The oil pressure guage should sit around 30 or so at idle, 45 going down the road, and 60 when the RPM's go above about 2500-3000. This is just how GM set them up. If you watch the actual oil pressure on a scanner then you would see just what they run.
__________________
89 HYDRA-SPORTS 2000CC, 200HP EVINRUDE

http://www.thetruckstop.us/forum/showthread.php?t=10142
thefermanator is offline   Reply With Quote
Old 01-11-2011, 04:44 PM
  #18    
Senior Member
 
Join Date: Jan 2006
Location: Sunny florida
Posts: 11,708
Default

I've found that the engines with VVT have variable pressure..some is bled off to control the cam timing.
billinstuart is offline   Reply With Quote
Old 01-11-2011, 04:57 PM
  #19    
Senior MemberCaptains Club Member
 
Join Date: Feb 2007
Location: MA
Posts: 4,339
Default

Quote:
Originally Posted by billinstuart View Post
I've found that the engines with VVT have variable pressure..some is bled off to control the cam timing.
Does GM even make a V8 with VVT? How would you do it with a push rod engine?
__________________
'05 Pacific 1925
MacCTD is offline   Reply With Quote
Old 01-11-2011, 05:04 PM
  #20    
Senior MemberCaptains Club Member
 
Join Date: Oct 2006
Location: Utopia
Posts: 5,075
Default

I have a 07 Suburban,same deal.Great ride no complaints.
hanson is offline   Reply With Quote
 
 
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 



©2009 TheHullTruth.com

Powered by vBulletin® Version 3.7.6
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.2.0