Oil pressure low at idol

When they call me with this issue, a lot of times it is a issue with the bearings,  you can try a manual that is the quickest way to check, I am not sure how the motor was built, but really depends on the crank style, the rod style, the bearing style used, 

if it has a stock crank with aluminum bearings,  i would think the oil hot would be around 30-35,  with a 0-40 weight,  

DO NOT THROW THICK OIL IN THE MOTOR LIKE A 20-50 WITHOUT KNOWING THE BEARING CLEARANCE,  this can cause some issues, 

If you are using a stock rod with stock crank, with the correct bearing clearance like a .002/.0023 then you should see 40psi hot idle with a 0-30 -  0-40 weight, 

Again what is in the Motor, 

What pump, what spring, 

This all plays into how oil pressure in a motor 

Unfortunately with the LS platform oil pans even if you have bearing material and even a lot of bearing material in the pan, it sometimes will not show up in the oil change,   we weld a drain plug with a pocket into the bottom of the pan, this will catch every little thing in the oil,   

We spend hours setting up Main bearings,  for a LS it has to be correct, or they just do not last,   

Couple of things to check 

  • pull the side plug above the oil filter and see if the barbell is installed, you can see it or put a 3/8 extension up the hold to see if it hits it, 
  • pull the Alternator off, pull the side plug off and look for the freeze plug in the front, they can come out, 
  • pull drain plug drain current oil,  and run the lightest weight oil into the motor, with the motor off, into a White bucket and look for bearing material, any material 
  • find out the bearing clearance,  if it is around .00295-.0032 then yes, you can run 15-50 or 20-50  
  • if a pump relief valve gets stuck, there is a good chance it is because, of bearing failure, not pump malfunction

Did the motor cavitate,  we had a motor that they thought it had no oil so they put in more oil, this destroyed the pump, looked like it was ran for hours with no oil in the pump, 

Was the pump centered to the crank,  if not it can damage the pump and have oil loss issues, 

and only had this one time,  but we had a cracked crank after it was turned and never mad good oil pressure, then a couple trips in the crank broke,  

Taking the motor apart, most of the time we can figure out what went wrong,       

 
basketcase said:
I believe this is a typical problem off the LS platform.  The O ring around the pickup at the bottom of the pan goes bad.  Will have to drop the pan and replace.  I guess what happen is under low idle, it struggles to get a good suction, like you are seeing.  But under load, it is fine.  I would start there.

Jonathan  
Click to expand...
this is easy to check,  

they dont go bad, they get installed wrong, 

If you have a bad O ring, it just does not make good pressure at idle, and will take a long time to make any pressure, sometimes will have to rev to make pressure, 

quick check,  add 3 extra quarts 

if the pressure jumps up super hi,  then bad o ring,

The 3 quarts will submerge the pump past the pickup o ring, and is a quick way to check,   only do this at idle and small rev couple time, then drain quickly, do not run full idle with extra oil or it can cavitate the pump,    

Are you running a WIX filter,   we had --2-- yes TWO motor loose oil pressure, will find the pick, the filter fell apart and was stuffed in the pickup tube screen

I stick to AC Delco, Moroso, or K&N,  it is not about the filtration, it is about the FLOW, on a sand car,   I use a System one oil screen like the fuel filter.  

 
Kingkong said:
Autometer gauge  with the typical autometer sender 
Click to expand...
If it's a short sweep gauge:

[SIZE=medium]Pressure[/SIZE]

2241 (0-80 PSI)








PSI


Ohms




0


73




20


30




40


21




60


15




80


10







2242 (0-100 PSI)









PSI


Ohms




0


250




25


158




50


111




75


75




100


43




 
J Alper said:
this is easy to check,  

they dont go bad, they get installed wrong, 

If you have a bad O ring, it just does not make good pressure at idle, and will take a long time to make any pressure, sometimes will have to rev to make pressure, 

quick check,  add 3 extra quarts 

if the pressure jumps up super hi,  then bad o ring,

The 3 quarts will submerge the pump past the pickup o ring, and is a quick way to check,   only do this at idle and small rev couple time, then drain quickly, do not run full idle with extra oil or it can cavitate the pump,    

Are you running a WIX filter,   we had --2-- yes TWO motor loose oil pressure, will find the pick, the filter fell apart and was stuffed in the pickup tube screen

I stick to AC Delco, Moroso, or K&N,  it is not about the filtration, it is about the FLOW, on a sand car,   I use a System one oil screen like the fuel filter.  
Click to expand...
Some great points here from JAlper regarding Oil flow - I have seen bad filters as well. Never with a Wix XP, but anything is possible - These are mass produced in Huge numbers. I Only break in engines on AC Delco because they may not filter as well as some, but they flow better, and we change our oil nearly every trip.

When someone has an oil Pressure issue, I cut open the oil filter - even on same brand I some times see different quality inside. 

I have also seen a Fram Filter blow apart when people running what they think is good 20w-50 in a tight engine and they see 80Lbs cold at idle and do a Baller out of camp dead cold ...

 
Last edited by a moderator:
Fullthrottleguy said:
Some great points here from JAlper regarding Oil flow - I have seen bad filters as well. Never with a Wix XP, but anything is possible - These are mass produced in Huge numbers. I Only break in engines on AC Delco because they may not filter as well as some, but they flow better, and we change our oil nearly every trip.

When someone has an oil Pressure issue, I cut open the oil filter - even on same brand I some times see different quality inside. 

I have also seen a Fram Filter blow apart when people running what they think is good 20w-50 in a tight engine and they see 80Lbs cold at idle and do a Baller out of camp dead cold ...
Click to expand...
I'm sure that's fun to clean up...

 
Fullthrottleguy said:
One of the few times have gone back to the Moho and let them have all the fun
Click to expand...
Since there are so many pumps available for LS motors…

I wonder if rather than run 20w50 on a “loose” motor, it would be better to run a higher flow pump and 5w30 to get the pressure you want…

I’m thinking probably yes. 

 
Rockwood said:
Since there are so many pumps available for LS motors…

I wonder if rather than run 20w50 on a “loose” motor, it would be better to run a higher flow pump and 5w30 to get the pressure you want…

I’m thinking probably yes. 
Click to expand...
As I understand it you need film thickness for load even if you have more flow the looser clearances under load (thousands of Lbs) will displace thinner oil films and bearings will get hot and transfer metal - happens fast at high RPM

 
Fullthrottleguy said:
As I understand it you need film thickness for load even if you have more flow the looser clearances under load (thousands of Lbs) will displace thinner oil films and bearings will get hot and transfer metal - happens fast at high RPM
Click to expand...
True.  Probably some combination of the two.  Wonder what the relationship between weight and pressure is as far as film strength.  Hrmmmmm.....

 
Rockwood said:
Another question: what're your oil temps when you stop?  If you're at 300*F, there's your problem.... :biggrin:
Click to expand...
I do also have a oil temp guage on mine, at 310 it still makes 25lbs of pressure,  interesting to see what the bearings look like 

 
With my stock oil pump on my LS1, I'm sure I hit over 300F on hard runs based on what I saw on my gauge before I added the cooler.

When CBM tore my motor down, they said the bearings had for sure seen some serious heat.

I run a Melling 10296 pump now, with a oil pan baffle kit/tray and a CBR oil cooler.

I never see temps over 265 now and never below 35psi.

Cold start I idle at about 50-55psi, with 20W50.

 
Last edited by a moderator:
Rockwood said:
For reference: stock pump?  
Click to expand...
For me it depends on the size of the Crank,  for a Stock i run a stock style pump with upgraded springs,  stroked i go to a mellings 10296-10355 depending on size of motor,  we use the red or the green spring depending on bearings clearance, 

Today was a learning lesson,  I had a bearing issue with a LSX, and called Clevite and they where very helpful,  

MAHLE Aftermarket North America | Installation Tips (mahle-aftermarket.com)

Also you can take the training courses, 

MAHLE Aftermarket North America | Training (mahle-aftermarket.com) 

 
J Alper said:
For me it depends on the size of the Crank,  for a Stock i run a stock style pump with upgraded springs,  stroked i go to a mellings 10296-10355 depending on size of motor,  we use the red or the green spring depending on bearings clearance, 

Today was a learning lesson,  I had a bearing issue with a LSX, and called Clevite and they where very helpful,  

MAHLE Aftermarket North America | Installation Tips (mahle-aftermarket.com)

Also you can take the training courses, 

MAHLE Aftermarket North America | Training (mahle-aftermarket.com) 
Click to expand...
Nice.  Melling has a lot of resources too.  I didn't realize the pump floated on the crank and wasn't positively located (like in every other engine).  Luckily, I watched the Melling video on pump install before buttoning everything up: need to spin the crank 360* prior to tightening to center the pump. 

Which is my main gripe on the "LS" platform in general: would it have killed GM to use some motherfonking dowel pins?!?!? :biggrin:

 
Rockwood said:
Nice.  Melling has a lot of resources too.  I didn't realize the pump floated on the crank and wasn't positively located (like in every other engine).  Luckily, I watched the Melling video on pump install before buttoning everything up: need to spin the crank 360* prior to tightening to center the pump. 

Which is my main gripe on the "LS" platform in general: would it have killed GM to use some motherfonking dowel pins?!?!? :biggrin:
Click to expand...
also another vid, show even easier,  they use 3 feeler gauges, another vid shows one long gauge that he wraps around the gearator 

 
J Alper said:
also another vid, show even easier,  they use 3 feeler gauges, another vid shows one long gauge that he wraps around the gearator 
Click to expand...


Rockwood said:
Nice.  Melling has a lot of resources too.  I didn't realize the pump floated on the crank and wasn't positively located (like in every other engine).  Luckily, I watched the Melling video on pump install before buttoning everything up: need to spin the crank 360* prior to tightening to center the pump. 

Which is my main gripe on the "LS" platform in general: would it have killed GM to use some motherfonking dowel pins?!?!? :biggrin:
Click to expand...
The Pumps are very different in width and gearotor size - so the dowel idea probably would not work unfortunately. I have plastic shims to set them up - its literally 1 minute of time - since I Mic the crank and bearings and journals and rods and use plastigauge too - the  1 Minute on the Pump is the easy part

I use Clevite bearings almost exclusively because they support builders and have great reps, I sat in on a training they did for old machine shop I was impressed. But they are softer than Kings so in a 30LB+ Turbo I would probabl;y use Kings 

 I can tell in seconds if the car ran hot  - LS bearings are easy to read, but I usually see the Thrust  be the issue with aftermarket cranks and most shops (not race builders) never even check

 
Last edited by a moderator:
You must log in or register to reply here.
Back
Top