I have a 2000 silverado 1500 Vortec 5.3 with 103,000 miles . When i start my truck after it has been sitting for more than 4 hours or so , i get a loud knocking noise that goes away after a 40-60 seconds. I am running Castrol GTX 5w-30. Not sure if i sould add an additive or switch to synthetic . I really dont feel like pulling heads
Castech head cracking issues. Affects most 5.3 heads from 99-05. There's a weak spot in one of the oil drain holes closest to the fire wall. Cause a wee bit of coolant to leak into the head - it also affects that lifter and doesnt allow it to pump up as quick as normal. Easy to spot the issue by popping a valve cover off and looking for sludge - also puff of blue smoke out of tailpipe on start up.
Ignore the Vehicles Affected part of this TSB - theres more TSBs detailing other vehicles.
Castech head cracking issues. Affects most 5.3 heads from 99-05. There's a weak spot in one of the oil drain holes closest to the fire wall. Cause a wee bit of coolant to leak into the head - it also affects that lifter and doesnt allow it to pump up as quick as normal. Easy to spot the issue by popping a valve cover off and looking for sludge - also puff of blue smoke out of tailpipe on start up.
Ignore the Vehicles Affected part of this TSB - theres more TSBs detailing other vehicles.
piston slap. pulling the heads wont fix anything. same issue with my 2000 yukon 5.3. I have 180k on original short block, and i just let it warm up before I put in gear. No blue or white smoke, and I believe the 2000 engines are before Castech was involved. Which oil you use wont really affect the piston skirt clearances, its more of a temperature issue than a lubrication issue. Ive seen engines that have ran both conventional and synthetic oil make the same noise. On pretty much any LS based engine the heaviest oil I would put in them is 10-30, unless you have really low oil pressure. Even with 180k on mine I still have 80psi at cold start and 45-50 at hot idle. I put 10-40 in it once and my pressure gauge was maxed all the time, certainly not good for the oil pump. just my $.02.
i had a question about this as well. getting a little lifter tick on cold start up for a few seconds. but my main concern is that once my truck warms up, my idle oil pressure drops to about 25-30. but only once its gotten up to temp. cold start up oil pressure is a solid 40. and if i give it just a little gas it will go to 40 and higher depends on rpms just as normal. also the gauge shakes a bit only at hot idle 25-30psi. i'll have to get a video some time.
Yes a lot of the 5.3s knock on start up. Mine does it only when I start it up in the morning. For about 60 seconds. I let it warm up then go to work. Even after 8 hours sitting in the cold it doesn't knock. Only the first start up of the day. Nothing to worry about! Also the trannys are a little rough when they're cold.
i had a question about this as well. getting a little lifter tick on cold start up for a few seconds. but my main concern is that once my truck warms up, my idle oil pressure drops to about 25-30. but only once its gotten up to temp. cold start up oil pressure is a solid 40. and if i give it just a little gas it will go to 40 and higher depends on rpms just as normal. also the gauge shakes a bit only at hot idle 25-30psi. i'll have to get a video some time.
I have the same tapping issue in my 01 Silvy's 5.3 engine with 101,XXX miles. Light tap @ morning start up but seems more noticeable when the morning outside temps are 40 degrees or colder. Tapping last maybe 45-60 seconds at the most and then it's gone until the next cold start-up. No smoke, no coolant leaks/loss and I use Mobile 1 Syn with a Napa Gold Filter every 4,500 miles. Engine runs perfect otherwise. Glad to read that it's not a major issue to be concerned with.
A lifter would sound more like a hollow tapping noise. If its a slight knocking its piston slap. Once the truck warms up, if it goes away its probably Piston slap.
i had a question about this as well. getting a little lifter tick on cold start up for a few seconds. but my main concern is that once my truck warms up, my idle oil pressure drops to about 25-30. but only once its gotten up to temp. cold start up oil pressure is a solid 40. and if i give it just a little gas it will go to 40 and higher depends on rpms just as normal. also the gauge shakes a bit only at hot idle 25-30psi. i'll have to get a video some time.
Yep, piston slap. Very common with these motors. Nothing to worry about, chances are it's done it for ever you just never noticed it. The first time I noticed mine was at a drive through after the truck was warm, I could hear it when I pulled next to the building. Not noticable when warm unless you are in a tunnel or next to a building or something like that at idle or low RPM. Google piston slap and gm
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