I have read through some threads here, and other sites, regarding low oil pressure on 5.3L. They have discussed sensors and such, but I have not seen my particular issue. So I will try to give as much detail, and apologize for being longwinded. I have an '02 Silverado 5.3L. At the beginning of this story, 2 years ago, it had about 200K. It has 237K now. Back then I had the oil & filter changed at a locally owned quick lube. I drive 8 miles one way to work normally, but a few days after the oil change i drove 100 miles one way, to a work site. On the way home that afternoon, on 4 lane at 80 MPH i start hearing this tapping noise & freak out. I slowed way down, exited, sat a bit, checked oil & it was fine. Took off again with heart rate higher than RPM, still 80 miles from home. Did it again, but I made it & went to my mechanic the next day. In our discussion he asked if i had the oil changed at "Franks". Uh, yes. So, i'm the 4th one he's seen and he says "Frank" is using cheap imported filters that are collapsing under pressure. My guy changes the o & f and i'm fine for months till i try to pull a loaded trailer, then the oil pressure drops. Once it falls below 40 the tapping starts. So, this has gotten progressively worse over the two year span, to the point that, with no load, just normal driving, between oil changes the pressure drops lower and lower at idle(around 40), and doesn't stay as high (around 50 was normal) when driving. I'm taking it to him this week, but i really want to hear from some other folks before I do.
Oil Pressure drops, tapping engine, under load
- Thread starter Daren Blades
- Start date
Sparky
Member
- Dec 4, 2011
- 12,927
So it only makes noise when the oil pressure starts to drop? Sound like upper end tapping (lifters/valve train) or a lower down, deeper noise (like a rod)?
Does it matter how warm the engine is? Is it quiet and good pressure until the engine warms up, or does it not matter at all?
What oil/filter are you typically using?
Does it matter how warm the engine is? Is it quiet and good pressure until the engine warms up, or does it not matter at all?
What oil/filter are you typically using?
Yes, once it goes below 40 the tapping on top of the engine starts. Under normal driving that will never happen, but traveling long distances, 2-300 miles, gradually it will go below 40 and start tapping. When I stop for a bit it goes back to normal but the interval gets shorter each time during the trip. I was using Castrol 20-50 but switched to 10-w40 on mechanics recommendations. It does matter how warm the engine is. Pressure is fine until it warms up.
Sparky
Member
- Dec 4, 2011
- 12,927
20W-50 is way too thick. That engine calls for 5W-30 originally. Were you using it to try to counteract the low PSI?
You might have a worn out oil pump.
You might have a worn out oil pump.
I'm definitely in complete agreement with @Sparky here... Using extremely High Viscosity Oil has one unexpected and disturbing result: It causes the Fine Paper Oil Filter Elements to bog down so much (think of Molasses being squeezed through layers of Coffee Filters...) such that the Oil By-Pass Spring adjacent your Oil Pump MUST give way...and allow thick, unfiltered oil to run rampant through the oil galleys and wind up depositing all kinds of crap into the soft babbitt metals comprising the surfaces of all your bearings. Not Good! The other bad side effect is that if your Oil Pressure Sensor is UPSTREAM of the backed-Up Filter... then the Low Pressure Reading will occur because of the resistance to the flow sufficient to put pressure on the sensor at low RPM and Idle Engine speeds is reduced by the back up.
In cases where Engine Builders removed the By-Pass Valve on High Performance Builds and installed a threaded, sealed plug instead. The resulting failure cascade was (1) The Oil Filter Cannister BURSTS wide open under extreme oil build up of Oil Pressure behind the filter paper segments and (2) Catastrophic Engine Failure from the instantaneous and complete loss of Oil Pressure at Higher RPM.
Years ago, I watched a mechanic suffering with this same “noisy tappet” issue and I suggested to him that instead of using oil that was just Way Too Thick... that perhaps he should treat the engine by using Marvel Mystery Oil. I know.... this sounds like a Bad Joke...but since I am not into “Schadenfreude”... I assured him of my sincerity. It is worth repeating here for you:
Marvel Mystery Oil allows engines clogged up in the Top End to be loosened of all the Junk and Dirt that often collects deep inside sluggish Push Rods and loosens and cleans out dirt and Junk Particles nested inside of dirty clogged lifters and by mixing one entire bottle with the remainder being your recommended viscosity of 5W-30 and the BEST K&N Oil Filter for your engine.... Don't be surprised when things start to get quiet under your Valve Covers! This might seem counterintuitive... but from the personal experience with watching him take the idea to heart and later with my own experiences on dealing with engines presenting Noisy Valve Trains... I think that trying this MMO Experiment will be more than worth your while.
Here is link to the product:
http://www.autozone.com/motor-oil-a...ve-and-cleaner/marvel-mystery-oil/238994_0_0/
Here is a testimonial similar to my own:
http://www.jalopyjournal.com/forum/threads/marvel-mystery-oil-does-it-work.93316/
Nobody in their right mind acts in this manner on a Car Repair Forum when someone is in trouble:
http://dictionary.reference.com/browse/schadenfreude?s=t
In cases where Engine Builders removed the By-Pass Valve on High Performance Builds and installed a threaded, sealed plug instead. The resulting failure cascade was (1) The Oil Filter Cannister BURSTS wide open under extreme oil build up of Oil Pressure behind the filter paper segments and (2) Catastrophic Engine Failure from the instantaneous and complete loss of Oil Pressure at Higher RPM.
Years ago, I watched a mechanic suffering with this same “noisy tappet” issue and I suggested to him that instead of using oil that was just Way Too Thick... that perhaps he should treat the engine by using Marvel Mystery Oil. I know.... this sounds like a Bad Joke...but since I am not into “Schadenfreude”... I assured him of my sincerity. It is worth repeating here for you:
Marvel Mystery Oil allows engines clogged up in the Top End to be loosened of all the Junk and Dirt that often collects deep inside sluggish Push Rods and loosens and cleans out dirt and Junk Particles nested inside of dirty clogged lifters and by mixing one entire bottle with the remainder being your recommended viscosity of 5W-30 and the BEST K&N Oil Filter for your engine.... Don't be surprised when things start to get quiet under your Valve Covers! This might seem counterintuitive... but from the personal experience with watching him take the idea to heart and later with my own experiences on dealing with engines presenting Noisy Valve Trains... I think that trying this MMO Experiment will be more than worth your while.
Here is link to the product:
http://www.autozone.com/motor-oil-a...ve-and-cleaner/marvel-mystery-oil/238994_0_0/
Here is a testimonial similar to my own:
http://www.jalopyjournal.com/forum/threads/marvel-mystery-oil-does-it-work.93316/
Nobody in their right mind acts in this manner on a Car Repair Forum when someone is in trouble:
http://dictionary.reference.com/browse/schadenfreude?s=t
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So, lets assume it wasn't 20-50 but more proper viscosity, because i could have stated that incorrectly. I should discuss checking the oil pump with my mechanic guy.
Mooseman
Moderator
If it is, it will be a big job, similar to replacing the timing chain, since the pump is in the front cover.
How to replace I6 timing chain and tensioner
How to replace I6 timing chain and tensioner
Sparky
Member
- Dec 4, 2011
- 12,927
Mooseman
Moderator
It looks like BOTH of you Gentlemen are very correct in this case. Here are the complex repair procedures for making an R&R of the Gerotor Style Oil Pump:
http://www.justanswer.com/chevy/4dq7n-chevrolet-suburban-1500-need-procedure-remove.html
http://www.justanswer.com/chevy/4dq7n-chevrolet-suburban-1500-need-procedure-remove.html
He's closed till Monday. Ah, small town America. The rear seal has been leaking for a while. I figure the pressure from a new pump might give it the boost it needs to completely hemorrhage. So, i'm expecting i nice contribution to his causeHence why we need vehicle info below the name. It's probably still a pretty involved labour intensive job, similar to the I6.
Sparky
Member
- Dec 4, 2011
- 12,927
With how intensive of a job it is I wouldn't want to just throw a pump at it hoping that is the issue. Definitely talk it over with someone familiar with all that. We can help a lot on here, but I'm not talking from first-hand experience on any sort of oil pressure problems from a pump. My brother's old ford did, but that's a Ford, not a GM, no idea what kind of pump it had. My only oil pressure issues that I had was when I spun a rod bearing on my old car, but that was also accompanied by a rather obvious bottom end knocking 
Before you have to take the vehicle in for any major repairs...Here are two videos that show a more direct attack of this very problem you are facing with the very same engine in your vehicle... but your level of mechanical skill should be very sound before attempting this method. This man is a very competent mechanic who has done quite a few excellent videos as he makes his living repairing motor vehicles: (@Sparky ...You got an Honorable Mention here!)
Here is another supporting video using the same Berryman B-12 Carb Cleaner and technique:
But If the problem persists... If you can imagine how many rotational cycles this poor engine has had to endure over 237,000 miles; even if you averaged the RPM at say, 1,500... That number is going to be a staggeringly huge amount of active stress on this engine over its lifetime. It is not a far reach to assume that by now, the bearing clearances throughout all of the rotating mass assembly have worn so far out of reasonable specification to the point where the clearances are so large... that maintaining normal oil pressure is probably out of the question. It might be time to get a realistic price on a low mileage motor and just do an R& R of the Engine... because the price for parts and labor to do the oil pump alone should make this alternative idea more appealing. If you can picture this... if a brand new engine has .020 clearance for the Main Bearings of the Crankshaft ... and now that distance has worn to around .035" - .040"... Then your crank journals are hemorrhaging oil at the radius line of each bearing, making it impossible for the Oil Pump to keep the pressure up. Please let us know if these ideas work and help you dodge a huge bullet on engine repairs.
Here is another supporting video using the same Berryman B-12 Carb Cleaner and technique:
But If the problem persists... If you can imagine how many rotational cycles this poor engine has had to endure over 237,000 miles; even if you averaged the RPM at say, 1,500... That number is going to be a staggeringly huge amount of active stress on this engine over its lifetime. It is not a far reach to assume that by now, the bearing clearances throughout all of the rotating mass assembly have worn so far out of reasonable specification to the point where the clearances are so large... that maintaining normal oil pressure is probably out of the question. It might be time to get a realistic price on a low mileage motor and just do an R& R of the Engine... because the price for parts and labor to do the oil pump alone should make this alternative idea more appealing. If you can picture this... if a brand new engine has .020 clearance for the Main Bearings of the Crankshaft ... and now that distance has worn to around .035" - .040"... Then your crank journals are hemorrhaging oil at the radius line of each bearing, making it impossible for the Oil Pump to keep the pressure up. Please let us know if these ideas work and help you dodge a huge bullet on engine repairs.
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By now... The inside of your engine has the same kind of Black Mung and Sludge built up as depicted here. If you tend to go longer between Oil Changes... this is what gets invited to live inside the engine:
Clogged Oil Sensor Screen causes fluctuations and Low Oil Pressure indications:
Another intimate look at this dynamic:
Clogged Oil Sensor Screen causes fluctuations and Low Oil Pressure indications:
Another intimate look at this dynamic:
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Update: My guy wants to remove the oil sensor screen. I asked him to take off the valve cover and clean on the drive side since I'm pretty certain that is the side. To my way of thinking, the truck is there anyway, and evidently it is an easy procedure, based of the videos above. And thanks for those if I haven't said so already. Just a matter of scheduling at this point.