No Oil pressure after Repairs

[duarte6983]

Hello All,

So this weekend I repaired a leaky oil pan, oil pickup tube, and a fresh oil change with Synthetic oil and Lucas additive. I also cleaned the lifters with some B-12 Carb cleaner ( some of the tubes that lead down to the lifter you could not see through which I figured caused that annoying ticking ). After all this work my truck now has a low oil pressure warning and sounds like a diesel truck. I didn't have these issues prior so I'm a bit stumped if it is the Oil Pressure sensor or the Oil pump. Any advice and knowledge would be appreciated.

2005 Chevy Silverado Z71
190K

5.3L

[Jsdirt]

The pump might be taking a while to prime, since the pan was off. Either that, or that pickup tube is leaking again, worse than before. Or, there's trash blocking an oil passageway - with spraying carb cleaner down there, it may have dislodged a large chunk of crap that plugged up a passageway.

 

I don't know how guys are priming these newer engines, but in the day, we'd yank the distributor, and get the electric drill spinning the oil pump before we put everything back together. Used to fill a pan full of oil to cover the pickup tube, then have your buddy run the drill. After doing that a few times, you'd see how well everything was working. It would empty the pan in seconds. Made a mess, but was worth the peace of mind. In later years I'd just fill the crankcase, run the drill for a few minutes, and wait to see oil coming out the pushrods & rockers.

[certified22]

That won’t work the oil pump is on front of motor and it will need primed there are several YouTube videos on how to do this and you can make your own or rent one from the local parts store but it will require a priming tool mellings has a good video on priming the oil pump on you tube 

[certified22]

I gotta tell you cause you sound just like me I’ll keep this short if you want to know more I have several posts on here about this oil pressure situation in an 04 z-71 Tahoe 5.3 went through everything you are even used 5 qts synthetic royal purple oil and 1 qt Lucas oil stabilizer every 3000 miles with an AC Delco filter I used to have 40 psi at idle and 80 psi on hiway now I’ve got my sending unit unplugged so I don’t have to listen to the alarm sounding at every stop sign cause I got about 4 psi at idle and maybe 16 or 18 with my foot in it been like that for two or three years now  

[Jsdirt]

Ahh, yeah, the LS front pump - don't know where my brain was there.

 

To the OP - with 190k on a 5.3, it was probably getting close to being at the end of it's life before that carbon got loosened up.  There's also a screen that should be cleaned out - can't recall where that screen was, but when that plugs up, oil pressure goes WAY down. Plus, there are at least a couple CRITICAL o-rings that can cause oil pressure loss if missed.

 

I'm rusty on my LS knowledge - I read a bunch of stuff on it a year or so ago, but have forgotten most of it, since I don't rebuild engines (modern engines anyway). Easier to just buy a crate engine.

[txab]

You mentioned replacing the pick tube..... did you make sure the o-ring stayed in place n and is in position?. Without it you'll be sucking air. But priming the pump could be an issue as well. No screen under the pressure sensor on an '05. AFM engine have that little jewel

[Jsdirt]

Ahh, thanks for the great info! 

[certified22]

Txab is correct no screen under sending unit till afm in 07 but the O ring is crucial and the right o ring as well when i replaced my oil pump it came with 3 or 4 different o rings have you ever had a stuck lifter maybe when it was cold out that you can recall a damaged lifter will cause this issue your having and worse case a spun cam bearing but I’d definitely start with priming the oil pump then move on to the oil pump itself cause it has a bypass spring loaded valve Incase you get to much oil pressure it will open up and dump right back into the pan causing this issue as well I can go on and on with the possible causes believe me been where your at still there just finally gave in and quit worrying saved my money and bought another motor ain’t swapped out yet cause this one with no oil pressure is a beast and doesn’t seem to mind not having it 

[Black02Silverado]

Can you hook up a mechanical oil pressure gauge in place of the factory one.  That would give you a good idea as to what the true pressure is.  

 

As for the pump going out.  It is possible. I change the oil for a friend that has a 2005 Suburban with the 5.3 with 365k miles on the all original drive train.  He just uses what ever oil is cheapest until he started having me change the oil which was at 300k miles.  Other than it leaking like crazy it runs great.

 

Not bashing and please don't take this the wrong way but you do not need to run an oil additive.  As posted above, a 365k mile 5.3 ran on cheap oil.  Trust me this guy is all about saving money. At least he had his oil changed out and usually around 5k miles but some times he comes in at 8k to longer.  Todays oils are just fine, no need for an additive.