LS with Low to 0 Oil Pressure

Cable Guy

Cable Guy

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I have an LS2 that only has around 25Lbs of pressure when cold after engine and oil are hot I have 0 oil pressure.

Here’s the kicker when I went to change the oil and after draining the pan, I removed the oil filter and there must have been at least half a quart of oil that flowed out over the filter. I have never seen that before.

Thinking clogged filter was my problem, I replaced filter and still low pressure. When I pulled the new filter, again half a quart of oil or more flowed out over the filter.

Anyone ever had this happen? Is there something clogged?

[SIZE=11pt]I am getting ready to drop the oil pan and check O-ring on tube feeding pump just to make sure it’s still good[/SIZE]

 
Lost spring pressure on relief valve?
does LS oil system work the same as SBC?

I had one stuck closed on a Corvair  engine that cause way too high oil pressure.

 
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The filter always makes a mess for me.  What weight oil are you running? also what filter?  run 20/50 and a K&N oil filter.  K&N are not the best filter so they flow much better.  should be changing oil every couple of trips. When you rev your engine how much oil pressure do you have? at 4,000 rpm you should have at least 40 psi, When Hot mine psi is 17 to 20. cold 30 to 40. hope that helps.

 
Change oil every trip. Figure oil is cheap compared to motor. Used K&N filter and still had a bunch of oil flow out over the filter when it was removed. Never see more than 25 oil pressure even with high RPM.

 
Oil coming out the filter is totally normal.

I punch a hole in the bottom of mine to help not make a mess.

Maybe a gauge?

0 pressure at hot and the motor isn't knocking means you don't have an oil pressure problem, you have a gauge prolem.

 
Mine does the same thing, flowing over the oil filter mess.

I added a manual oil pressure gauge from CBM right at the filter, and it reads more accurately than my dash gauge.

I see about 45PSI on a cold start.... but after long hard runs, it'll idle around 10-15PSI... but it still climbs with the revs, which is what I was told is important.  TT LS2, running 20/50 oil.  

 
Couple of reasons why it would happen if it was new, cam plate installed wrong, or pickup tube seal installed wrong, or issue with the rear cover gasket, but on a existing oil pump pressure relief stuck,

On a existing motor, i have only lost oil pressure with a customer once due to a filter, it was a WIX, the paper let loose and was sucked on the oil pump tube solid, but this made zero pressure all the time, 

Oil pump relief will get stuck if material is in it, but does not fail if the oil is clean and the motor is not coming apart, 

If you had low oil pressure and it was Knocking, then bearing failure, 

Most of the time if the motor is truly low on pressure, and the motor does not knock, them a cam bearing is pretty common, we use a retainer compound and fit the bearings to the cam size, and make sure it has the proper bearing clearance, We use a dial bore gauge to check the clearance on the cam, and the lifters, 

 
I'm going to check the pickup tube seal  and oil pump pressure relief this week

Thanks for all the input.

 
My motors make cold at start up on 15-50 syn around 75-80lbs cold, 

oil pickup tube is super easy to check, over fill the motor by 3 quarts, if the oil pressure jumps up with the pump submerged in oi than it is the pickup O ring, 

 
Dune savage said:
Does everyone agree 20/50 is the best weight to run?
Click to expand...
The issue with oil V, is bearing clearance, for a LS it can be as low as .001 clearance to .0035  so if you have a motor .0015 clearance running 20/50 you are pretty much killing the motor, or running a bearing .003 and running a 0/30 would cause the same damage. 

When it comes to the oil that i recommend. I send a bearing chart that was installed in the motor and what pump volume and pressure setting.  Without that it is a real shot in the dark.  

 
i would put a mechanical gauge on it i've seen a few times the sending units go bad i think oil gets on the other side of the diaphragm in the sending unit slowly while running causing the gauge to stop reading pressure. then when you let it sit the oil drains back into the oil system it will work for a little and slowly go out again. 

 
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