Generation III Internal Engine 1997-2006 LS1 | LS6
Sponsored by:
Sponsored by:

Oil pressure diagnosis

Thread Tools
 
Search this Thread
 
Old Oct 4, 2007 | 11:45 AM
  #1  
airwrench's Avatar
Thread Starter
Teching In
 
Joined: Jun 2005
Posts: 19
Likes: 0
From: Indianapolis, IN
Default Oil pressure diagnosis

Looking for input on the following problem:

5.3L '03 truck motor

On startup, shows low oil pressure warning light - gauge shows almost no pressure. Rev once, oil pressure comes up to around 40, light goes out, and is fine from then on (40psi at idle, 50-60 at road speeds).

Happens on every start.

from what I've read this might be one 1 of 2 things:

1. The plastic oil flow control plug at the back of the block right above the oil filter might be loose or broken - anybody have any experience with this? How would this cause the above symptoms?

2. The oil pump pressure relief is stuck in the "relief" position. Once I rev it, the higher pressure causes it to pop back. Doesn't seem to fit the problem, in that before you turn the truck off, at idle it seems to have fine (40psi) oil pressure.....

Any other thoughts?

Anything obvious like starving the oil pickup? (the dipstick indicates the oil level is fine - right up towards the top of the range).

Thanks for all input!
Reply
Old Oct 4, 2007 | 12:10 PM
  #2  
bczee's Avatar
TECH Senior Member
20 Year Member
Photogenic
Photoriffic
Shutterbug
iTrader: (12)
 
Joined: Jan 2006
Posts: 6,670
Likes: 6
From: Concord, CA
Default

Put a aftermarket gauge (manual) on and then watch it. Could be the OEM sender or gauge, OEM ones have been know to be off for many at times.
Reply
Old Oct 4, 2007 | 01:20 PM
  #3  
airwrench's Avatar
Thread Starter
Teching In
 
Joined: Jun 2005
Posts: 19
Likes: 0
From: Indianapolis, IN
Default

BCzee,

Thanks - I'll give that a try and see what happens. I heard from another source that if the plastic plug/flow director is loose or broken, you'd get pressure variations as you were driving that might seem random. My truck's pressure is solid and steady while being driven - so maybe the symptoms match a sender better.
Reply
Old Oct 4, 2007 | 01:21 PM
  #4  
airwrench's Avatar
Thread Starter
Teching In
 
Joined: Jun 2005
Posts: 19
Likes: 0
From: Indianapolis, IN
Default

By the way - for those that might have the plastic plug problem, the dealer quoted $1100 to replace it...
Reply
Old Oct 4, 2007 | 02:48 PM
  #5  
robertbartsch's Avatar
TECH Veteran
 
Joined: Aug 2002
Posts: 4,055
Likes: 1
From: Hartsdale, NY
Default

...that is why he is a dealer and you are a GM car owner!
Reply
Old Oct 4, 2007 | 06:54 PM
  #6  
airwrench's Avatar
Thread Starter
Teching In
 
Joined: Jun 2005
Posts: 19
Likes: 0
From: Indianapolis, IN
Default

Anybody have any advice on where/how to attach a mechanical gauge?
Reply
Old Oct 5, 2007 | 01:19 AM
  #7  
bczee's Avatar
TECH Senior Member
20 Year Member
Photogenic
Photoriffic
Shutterbug
iTrader: (12)
 
Joined: Jan 2006
Posts: 6,670
Likes: 6
From: Concord, CA
Default

Most will use the Oil bypass plate above the oil filter.. unless you have a oil cooler... then you might need to rig up some thing else off of one of the oil cooler lines.
Reply
Old Oct 5, 2007 | 08:28 AM
  #8  
DRCE's Avatar
Staging Lane
 
Joined: Nov 2006
Posts: 76
Likes: 0
Default

I like #2
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-1

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-2

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-3

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-4

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-5

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
story-6

Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

 Verdad Gallardo
story-7

Awesome K5 Blazer Restomod Comes With C7 Corvette Power

 Verdad Gallardo
story-8

10 Camaros You Should Never Buy

 
story-9

10 LS Engine Myths That Refuse to Die

 Verdad Gallardo




All times are GMT -5. The time now is 02:54 PM.

story-0
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-1
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-2
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-3
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-4
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-5
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-6
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-7
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-8
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE