Idle oil pressure keeps getting lower after rebuild - LS1TECH - Camaro and Firebird Forum Discussion

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

Idle oil pressure keeps getting lower after rebuild

Reply

Old 04-16-2018, 09:20 AM
  #1  
Teching In
Thread Starter
 
Join Date: Apr 2016
Posts: 19
Default Idle oil pressure keeps getting lower after rebuild

Hey guys, hoping I can get some help here as this is my first engine rebuild and I'm kinda stuck on what to do.
I have a 1971 C-10 that I put a 5.3 LM7 with a turbo in my truck and I recently rebuilt the motor. It has all new bearings, new cam, valve springs, ls9 head gaskets, and rod bolts.
Ive already rebuilt this motor once before and I'm having the same exact issue as I had before so clearly what I'm doing isn't working.
When I first started the motor, I had good oil pressure (not sure what is was exactly because my gauge in the truck just says L to H) but it was most of the way up. But as I let the motor idle and drove it a little bit, oil pressure was steadily dropping at idle as well as at rpm. It has gotten so low now that I can hear the lifters clattering so I know something is definitely wrong and I will be pull the motor to investigate.
What should I be looking for? I am pretty sure I installed the pickup tube correctly but have no idea if the barbell is in the rear of the motor. I never took it out but I have no idea if it's something that could fall out or if it is something that needs to be removed to put the cam bearings in.
Any help would be appreciated because I don't know what to do next since I thought I did everything correctly.

Thanks.
aruss99 is offline  
Reply With Quote
Old 04-16-2018, 09:47 AM
  #2  
TECH Enthusiast
iTrader: (11)
 
Join Date: Mar 2008
Posts: 707
Default

Long shot but possibly a easy fix. There was a thread a while ago about assembly line plugging some filters. Pretty cheap and easy enough to try before pulling motor. Real pressure gauges are pretty cheap also and after having the same prob twice I'd be slapping one in for sure.
tug686spd is offline  
Reply With Quote
Old 04-16-2018, 11:23 AM
  #3  
Teching In
Thread Starter
 
Join Date: Apr 2016
Posts: 19
Default

Originally Posted by tug686spd View Post
Long shot but possibly a easy fix. There was a thread a while ago about assembly line plugging some filters. Pretty cheap and easy enough to try before pulling motor. Real pressure gauges are pretty cheap also and after having the same prob twice I'd be slapping one in for sure.
Is that something that would risk damaging the bearings? I haven't drained the oil in the truck yet but did check the dipstick and there are some metal flakes. Not sure if that is usual since it is a new rebuild or if that points to a major issue internally.
aruss99 is offline  
Reply With Quote
Old 04-16-2018, 04:08 PM
  #4  
Staging Lane
 
Dragls's Avatar
 
Join Date: Jan 2014
Location: Hunters Creek, Orlando
Posts: 66
Default

Cut the oil filter open and look for bearing material or trash.
Dragls is offline  
Reply With Quote
Old 04-16-2018, 06:35 PM
  #5  
TECH Resident
iTrader: (12)
 
kossuth's Avatar
 
Join Date: Aug 2002
Location: New Market, MD
Posts: 963
Default

Sounds similar to an issue from 2 months ago

1. What oil pan are you running?
2. Do you know your pickup tube clearance to the bottom of the pan?
3. Did you replace the pump during the rebuild? If so with what pump?
4. Have you attempted to restart when the engine cools? If so does it have good oil pressure then?

if you were missing a pretty critical part like a galley plug you would have little to no pressure from the get go. Iím thinking your sucking air into the system due to too much pickup tube clearance or too aggressive of an oil pump vs the capacity and your sucking the pan dry.

If you have flakes on your dipstick thatís not good. The only place where glitter on your dipstick is a good thing is the strip club

Last edited by kossuth; 04-16-2018 at 06:42 PM.
kossuth is offline  
Reply With Quote
Old 04-16-2018, 07:11 PM
  #6  
TECH Regular
 
01CamaroSSTx's Avatar
 
Join Date: Feb 2015
Location: Texas
Posts: 460
Default

It doesn't sound good. What where your rod and main bearing clearances when you assembled the engine? Is it to spec or on the lose side? What weight of oil have you been using? Could be a number of things but it sounds like you have a clearance issue and/or incurred some oil starvation and you may be going back through it again real soon. Sorry!
01CamaroSSTx is online now  
Reply With Quote
Old 04-16-2018, 08:27 PM
  #7  
Teching In
Thread Starter
 
Join Date: Apr 2016
Posts: 19
Default

Originally Posted by 01CamaroSSTx View Post
It doesn't sound good. What where your rod and main bearing clearances when you assembled the engine? Is it to spec or on the lose side? What weight of oil have you been using? Could be a number of things but it sounds like you have a clearance issue and/or incurred some oil starvation and you may be going back through it again real soon. Sorry!
I don't remember off the top of my head what the numbers were but I know they were within gm spec. I had a little bit of metal on the drain plug and a few flakes in the filter when I cut it open. 4 qts of 5w30 and 2 quarts of amsoil 30w break in oil.

I started the motor when cold and had very little oil pressure so immediately shut it off.

I reused the factory pump, which may have been the death of me because I have no idea if the relief valves were stuck open or not.

I ordered a new oil pump, pickup, and cam retainer plate hoping that that was the issue instead of a bearing clearance issue and will install if no damage is found in the motor.

Not that I know much but I feel like it's unlikely to have the same symptoms I had before as far as oil pressure goes with the cause being loose bearings when I'm pretty confident they were within spec, but then again what do I know lol

I'm running the factory lm7 pickup and the factory lm7 truck oil pan
Attached Thumbnails Idle oil pressure keeps getting lower after rebuild-img_7053.jpg  
aruss99 is offline  
Reply With Quote
Old 04-16-2018, 09:25 PM
  #8  
LS1Tech Premium Sponsor
iTrader: (2)
 
Join Date: Apr 2016
Posts: 3,368
Default

Why reuse the old pump when new ones are so inexpensive? its good insurance and peace of mind really.
tech@WS6store is online now  
Reply With Quote
Old 04-16-2018, 11:02 PM
  #9  
Teching In
Thread Starter
 
Join Date: Apr 2016
Posts: 19
Default


Originally Posted by [email protected] View Post
Why reuse the old pump when new ones are so inexpensive? its good insurance and peace of mind really.
Yeah, I definitely regret not putting in a new one.

Now, I think I have some good news as to what my issue is, but maybe I am just seeing things that aren't actually there.

I tore the front timing cover off and got to the oil pump today. I couldn't look straight at the relief valve but I could get pictures and it looks to me like the valve is open.

Maybe someone who knows exactly what to look for could let me know if I'm right, or break the bad news that the valve is indeed closed.

Thanks

Last edited by aruss99; 04-16-2018 at 11:12 PM.
aruss99 is offline  
Reply With Quote
Old 04-17-2018, 06:28 AM
  #10  
11 Second Club
iTrader: (2)
 
A.R. Shale Targa's Avatar
 
Join Date: Feb 2011
Location: Fredonia,WI
Posts: 3,682
Default

Different rod bolts distorts the shape of the big ends
Since out of round it may not show up with a typical six o clock twelve o clock bearing mic job. Most likely pinching tight at the sides near the bolts and the rod bearings are relentlessly eating themselves to death
A.R. Shale Targa is offline  
Reply With Quote
Old 04-17-2018, 06:52 PM
  #11  
TECH Resident
iTrader: (12)
 
kossuth's Avatar
 
Join Date: Aug 2002
Location: New Market, MD
Posts: 963
Default

Originally Posted by A.R. Shale Targa View Post
Different rod bolts distorts the shape of the big ends
Since out of round it may not show up with a typical six o clock twelve o clock bearing mic job. Most likely pinching tight at the sides near the bolts and the rod bearings are relentlessly eating themselves to death
Not necessarily true. I've put ARP bolts in several sets of stock rods. Only had 1 or 2 rods out of the 24 or so I've put ARP bolts into checked out of round after the installation of the bolts. Didn't check them before hand, so they could have been out of round before hand :dunno While you have to check the rods after installation the comment that the rods are warped because of their installation is not necessarily the case.
kossuth is offline  
Reply With Quote
Old 04-18-2018, 11:30 PM
  #12  
Teching In
Thread Starter
 
Join Date: Apr 2016
Posts: 19
Default

Well, installed a new oil pump, oil pickup, and cam retainer plate on the motor today and was able to make oil pressure on the stand with just the starter. I wasn't able to make any oil pressure before with the old parts so I'm hoping that my oil pressure issue has been taken care of. Only time will tell
aruss99 is offline  
Reply With Quote
Old 04-19-2018, 10:24 AM
  #13  
TECH Regular
 
01CamaroSSTx's Avatar
 
Join Date: Feb 2015
Location: Texas
Posts: 460
Default

Originally Posted by aruss99 View Post
Well, installed a new oil pump, oil pickup, and cam retainer plate on the motor today and was able to make oil pressure on the stand with just the starter. I wasn't able to make any oil pressure before with the old parts so I'm hoping that my oil pressure issue has been taken care of. Only time will tell
Well I hope it turns out okay for you but from what you've described in your previous posts it sounds like your bearings may have some premature wear. The metal could be from initial start up too so keep your fingers crossed and let us know.
01CamaroSSTx is online now  
Reply With Quote
Old 04-19-2018, 10:47 AM
  #14  
LS1Tech Sponsor
 
Join Date: Dec 2008
Location: Santa Ana, CA. USA
Posts: 2,124
Default G Rotor Oil Pump Tech

Hi Russ, your pictures are great.

The material on the drain plug could be from the Oil Pump Rotors.

A Rotor "side view" picture could tell BOTH inner/outer condition.

The "G" rotor pump MUST ALWAYS be INSPECTED before reuse with NO wear observed.
The smallest amount of wear on the rotors (sides) has a GREAT effect on pump output.

SO I ASK, What method did you use to install/align the pump onto the crankshaft center ?

Your report could be of great help to LS-1 tech members.

Lance
pantera_efi is offline  
Reply With Quote

Thread Tools
Search this Thread

Archive Advertising Cookie Policy Privacy Statement Terms of Service

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: