NOT GMT400 RELATED. '09 5.3L oil pressure issue

[Schurkey]

They bought this truck in February; and have never changed oil on it.

I don't know what it has for a filter. The Oil Life Monitor shows 40% oil life remaining.

I told 'em to change oil and filter, see what happens.

Will update the thread when I know more--which will probably not be for a week or more.

 

[stutaeng]

What is involved in deleting the AFM system? I've read it, but can't recall. A cam swap, Non-AFM/DOD lifters and the LOMA cover? And a tune?

Gen IV 06-14 5.3 AFM DOD Delete Kit for 5.3L LMG LY5 LH6 LC9

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If it's still getting 20 psi, that's okay for lubrication, no? Does that pretty much revert it back to a Gen III engine?

 

[smokymtn65]

Yes. Mine was at 20 till lifter failed, and cause cam pin to shear. And being out of time bent all exhaust push rod and valves. Dont have it out yet so not sure what othe damage i have

 

[smokymtn65]

Had use a srage 2truck cam BTR single bolt, wont do that again either

 

[0xDEADBEEF]

Run thicker oil?

 

[0xDEADBEEF]

*without AFM

Richard

I think even the non-AFM Gen III has an inherent design weakness with the lifter trays. When they wear out the lifters can rotate and bad things happen.

 

[69project]

Posting here 'cause I'm not a member of an LS-specific forum.

Friend has an '09 Silverado with low oil pressure at the rear of the engine--sensor and dash gauge shows ~20 psi when warm at idle, in neutral. Sets an oil pressure code. My friend replaced the sensor and the screen under the sensor. No change.

We tested oil pressure with a mechanical gauge at the lower left front oil port; my gauge shows 50 psi when the dash gauge shows 20.

Is there a common reason why the LS engine would lose half of it's oil pressure from front to rear?

When was the last time your friend changed the oil filter? My friend's 2010 did the same thing. I pulled the sensor and the little screen and that didn't fix anything. I changed the oil filter and put fresh oil in it and everything went back to normal. When the filter goes into by pass, it restricts the flow of oil and sets off the caution light in the dash. I would change the filter out. Sounds like you have good oil pressure before it hits the filter.

 

[Schurkey]

I told 'em to change oil and filter, see what happens.

When was the last time your friend changed the oil filter? My friend's 2010 did the same thing. I pulled the sensor and the little screen and that didn't fix anything. I changed the oil filter and put fresh oil in it and everything went back to normal. When the filter goes into by pass, it restricts the flow of oil and sets off the caution light in the dash. I would change the filter out. Sounds like you have good oil pressure before it hits the filter.

Changed oil (5W-30) and filter, (Wix, but shorter than I'd prefer, and shorter than the Delco filter that was on there) dash gauge is now about 25--30 percent higher than it was. Still well-below what my gauge read, though.

Previous fully-warm-on-the-highway oil pressure was low-twenties, now it's mid-thirties. Cold and idle oil pressure is similarly higher than it was. The MIL light is out.

I'm no expert on LS engines. If this were a normal small-block, I'd take it as entirely adequate but "more would be better". My '88 starts up with the dash gauge pegged at 60, even though fully-warm at idle I've got ~13--15. But the sensor is in the same end of the engine as the oil pump, not at the opposite end. That may be a factor in the higher cold pressure.

Anyway, he's happy and I'm done with that issue. If there's future oil pressure problems, he can pull the engine for diagnosis.

I still have the old filter, I may cut it open and see what's going on inside.

 

[454cid]

Dont the ls engines regulate the oil pressure? I thought they had some sort of variable pump so as to not produce excess oil pressure.

 

[stutaeng]

The Gen III has a gerotor pump (positive displacement pump) with a spring. I really don't understand how it works, but there's a spring and a sort of valve. Maybe that's the bypass valve?

I don't know how the Gen IV oil pumps work. I want to say it's same or similar to the Gen III?

The Gen V (LT-series) use a variable displacement vane pump. It's basically the same as a 4L60e pump with the little slide and paddles. There's a solenoid in there too. I recently saw a tear down video the other day and was surprised to see that in there! I'm sure it has to do with efficiency and those MPG ratings.