jackmac

2008 Silverado 5.3 vin 0

Thanks for the reply jfath14, I have checked with a manual gauge at the port on the front of the block ,cold start it will read 45 psi and slowly start dropping to around 11 psi hot, gauge will respond quickly when engine rpm goes up. 1000 rpm it will raise to about 20psi when hot. Now with the manual gauge on the sending unit location 28psi cold and slowly drops to 5-6 psi hot and barley hits 10 psi at a 1000 rpm. No engine noise . The strange thing is literally the day before it done this I had 40 psi cold 28-30 hot but would go to 40 again at 1000 rpm. overnight it changed. I have done a VLOM mod where I block the oil passage to the solenoids and cut the tower gaskets and turned off the AFM with a HP tuner. I have done this same mod at least 20 times and never had a oil pressure issue so I'm thinking it is just coincidence it happened after the mod. ?? Could the pick up tube O ring do this or the AFM pressure valve in the oil pan? Thanks for any insight you have.

Did you find your problem? I have one doing the same thing. Thanks

I know this is a old one but did you find the problem??

Hey everyone. I have a unique one here, 2008 Silverado had a backfire issue. When it would go into 4cyl mode and as soon as it would go back to 8cyl it would backfire. Run great other then that, done all the normal checks, plugs, compression ,fuel pressure and so on. All checked out and no ses light. So I tuned off the AFM with HP tuner and done a VLOM mode consisting of cutting the tower gaskets and blocking the oil feed to the VLOM with a bushing like what crazed performance repair uses . Note I have done this tune and VLOM mode over 30 times with success on many 5.3 engines. This time I lost oil pressure on first start up after the modification. The day before the truck had 40-45 cold 30-35 hot and 30 in gear. Done the VLOM mode and first stat up I noticed it was barely 20psi and at 160 degrees it already dropped to almost 0. No engine noise, drove the truck and it runs fantastic now but has the pressure problem. I checked pressure at the sender location with a manual gauge and it in fact is low, around 5 pounds, 1500 rpm maybe 10. Checked it at the block plug in front close to the oil pump 50 psi on cold start then drops to 30ish when idle goes down to normal, hot idle it is at 12ish but when revved the least bit it will raise quickly to 30-35. I cant get myself to believe this is coincidence of something falling that immediate .Is it possible a lifter is loosing oil pressure at the tower? Thanks for any input and I will post what the problem and not leave a open thread so everyone can benefit.