99 5.3 vortec lifter tap
 

I have a 1999 Chevy silverado 1500 with the 5.3L vortec engine. Had 201k miles on it. Since I owned it it has 180k. Truck always started in the morning with a tap for 3 or 4 seconds then went away. Now it taps for 10 minutes or so until the motor warms up. It is the lifters. The noise is not coming from the bottom end. Motor runs great with good power it doesnt seem to hurt the motor in anyway. But my oil pressure runs at 15-20 psi and mabye 25 if i get on it. I know these trucks factory run 40-60 psi depending on rpms and engine temp. So my question is,could the low oil pressure cause this noise to get worse over time? Gm specs says it only needs 6 psi. But I think that is kind of low. I have a new oil pump just haven't got around to putting it in. Can a lifter tap harm your engine? I know it is common with these motors. And when it used to only be 3 or 4 seconds I just figured it was because my oil was all down in my oil pan on a cold start and take a few seconds to get to the top end of the motor. But now it is 10 or so minutes and is starting to worry me.

Oil weight could effect it too. When I first got my truck the oil pressure seemed low to me, I did an oil change going back to the oem weight and got more oil pressure. Also engines of this Era are known to have some piston slap at startup.

Yeah I've been changing oil. I run 5-30 pennzoil highmileage In the winter and 10-30 In fall, spring and summer. That's what gm suggest. I'm just worried to the enginne when it tapping and making noise for that long.

not a silverado but i have a 2000 suburban with the 5.3. 300k miles. when its cold i get the tick noise for a few seconds, then it goes away. BUT if i let it sit idle in park or drive for more than 10 minutes the tick comes back and doesnt go away until the rpms are brought up. according to oil pressure gauge while moving im around 40 but when stopped it dips as low as 5. also the check engine oil level light comes and goes sometimes, but each time i check it its right in the middle where its supposed to be. im using the recommended oil weight from the service manual. any suggestions? i know its high miles but most of them were highway, this truck went from MA to CA and back twice, and MA to TX twice, im the second owner.

Try a heavier weight oil to see if the pressure improves any.

X2. Thicker oil should give you more pressure.

The tapping you hear is caused by play in the valve train, lifters, push rods and rockers. Lifters are hydraulic, requiring oil under pressure to take up that play. If run to long without the proper oil pressure, a lifter can collapse, leaving a more permanent and louder tapping. A heavier oil is thicker and thus requires more effort to make it flow which will make your pressure reading go up but it will also cost you fuel mileage over time. This is a very common issue with Chevy small blocks. Once you replace your oil pump the tapping might not go away. You may need to check your rocker arm to push rod clearance to eliminate some of the noise. If a lifter is collapsed, you won't be able to adjust the rocker to push rod clearance enough to account for the slack. You can also try something like Marvel Mystery oil and see if it loosens a collapsed lifter back up.