Oil Pressure Issue - Top end build

[AnthonyNJ]

Hey Fellas

Long time browser first post on forum. Have an oil pressure issue that I cant track down and it's killing me. Have a 2007 Yukon Denali with a 6.2 vvt non DOD. So stock motor was pulled with 255k due to bad rear main seal leak and bad tap and piston slap. Got my hands on a clean l94 with 60k miles. Did a 156-401 Comp cam, 7.4 btr push rods, ls7 lifters and trays, trunion kit, dual valve springs, new oil pump, pickup tube gasket and oil pan relief valve.

Truck now runs great piston slap is gone and all noise is gone. When motor was first started until oil pressure was 65psi cold and sat at around 45 psi hot idle. After 500 miles changed oil and went with 5w40 rendline syn and found a bunch of flake in oil which is pretty standard for new parts. Now when I am driving I have around 30 Psi when hot driving and it falls to like 15psi when warm idle sometimes 10-12. Startup cold is 45ish psi. Swapped sending until and still no dice. I am not sure what to do at this point.

Dropping pan today to check pickup tube and o ring. When the truck is idling hot even when oil pressure drops all the way down no abnormal sounds like a vehicle with low pressure. Any idea's? Trucks killing me now runs though and i love it but I was hoping i'd be past this by now.

 

[swathdiver]

Hey Fellas

Long time browser first post on forum. Have an oil pressure issue that I cant track down and it's killing me. Have a 2007 Yukon Denali with a 6.2 vvt non DOD. So stock motor was pulled with 255k due to bad rear main seal leak and bad tap and piston slap. Got my hands on a clean l94 with 60k miles. Did a 156-401 Comp cam, 7.4 btr push rods, ls7 lifters and trays, trunion kit, dual valve springs, new oil pump, pickup tube gasket and oil pan relief valve.

Truck now runs great piston slap is gone and all noise is gone. When motor was first started until oil pressure was 65psi cold and sat at around 45 psi hot idle. After 500 miles changed oil and went with 5w40 rendline syn and found a bunch of flake in oil which is pretty standard for new parts. Now when I am driving I have around 30 Psi when hot driving and it falls to like 15psi when warm idle sometimes 10-12. Startup cold is 45ish psi. Swapped sending until and still no dice. I am not sure what to do at this point.

Dropping pan today to check pickup tube and o ring. When the truck is idling hot even when oil pressure drops all the way down no abnormal sounds like a vehicle with low pressure. Any idea's? Trucks killing me now runs though and i love it but I was hoping i'd be past this by now.

I used to race and build Buick engines and never had flake in my new builds. Something is not right. Thicker oil takes longer to make its way through the motor, I know the Corvette's run thicker oil when racing so going up to 40w may not be a big deal.

Check that o-ring and which oil pump did you use?

 

[donjetman]

Hey Fellas
After 500 miles changed oil and went with 5w40 rendline syn and found a bunch of flake in oil which is pretty standard for new parts.

Sorry to here your having problems

I assume you've been following all my posts onthe engine work I've been doing on the 6.2 L92 in my 07 Yukon Denali ?

I've built a lot of engines and metal flakes are never normal or ok.

My 135k mile L92 now has 55 psi cold start idle, 45 hot at hwy speed(1600rpm), 25ish hot idle. I'm running Mobil Delvac 1 ESP 5-40w, NAPA Platinum #47060 oil filter.

Let us know what you find

 

[ivin74]

With that many miles the crankshaft bearings usually wear out and the oil pressure drops. Not sure if this is your case but something to think about.

Google GM LS block oil passages images and you can see how the oil flow travels thru these engines

 

[Tonyrodz]

Did you go through the bottom end on the new motor? How were the crank bearings?

 

[AnthonyNJ]

With that many miles the crankshaft bearings usually wear out and the oil pressure drops. Not sure if this is your case but something to think about.

Google GM LS block oil passages images and you can see how the oil flow travels thru these engines

60k miles isn’t that many miles to have worn bearings, Just purchased saccitycorvette barbell and oil filter housing kit

I used to race and build Buick engines and never had flake in my new builds. Something is not right. Thicker oil takes longer to make its way through the motor, I know the Corvette's run thicker oil when racing so going up to 40w may not be a big deal.

Check that o-ring and which oil pump did you use?

Just a standard 12611289 GM pulling apart tomorrow

 

[AnthonyNJ]

Did you go through the bottom end on the new motor? How were the crank bearings?

didn't touch bottom end but checked and everything seemed good. Even on coldest mornings no taps or knocks at all, prior owner did 5-6k dexos 5w30 since new

 

[Tonyrodz]

didn't touch bottom end but checked and everything seemed good. Even on coldest mornings no taps or knocks at all, prior owner did 5-6k dexos 5w30 since new

So you know the maintenance history?

 

[swathdiver]

Just a standard 12611289 GM pulling apart tomorrow

Did you mean 12612289? If so, that's the best pump and has the 33 pound relief spring. Keep us posted.

 

[eohat]

I don’t know if your replacement engine has one, but check to see if there’s a screen under the oil pressure sending unit. It can become clogged and cause a low oil pressure reading, even if the sending unit has been changed. It’s an oil pressure sensor filter, part number 12585328. Hope you get it figured out.