Recalls & Engine Knock Info

[nomosyclone]

One question,is there a recall for the knocking?

[Creacher]

Hi guys. I've have reading up on this post. Their is bound to be infomation and testing done on what Oct to compression ratio charts as for what performance the power plant puts out. Look at at nascar, cart and indi cars. They all run a very high Oct of 104+ and look at the power gains they get out of this engines. I don't know the compression ratios but for some reason 10.5:1 pops into my head. I know their some lab tach/gear head goo roo thats all ready figured this out. If anyone can find some(true and provien)info. Please post it.

[GmcGuy]

my moms 01 yukon knocks alot when cold coems out of it after about 10 minutes if it's really cold. My truck with 5k miles had a slitht rap in the engine but had been ran very hard. It loves it

[99backinblack]

Hey just wondering if you all are having the same issue as me and my father who both have 99's (mines GMC and his is chevy Z71s) anyways, we both have push button 4WD and in both trucks after about 60 k miles we started getting the service 4wd light come on in the message center, and the lights on the push buttons either dim or go off completly when set in 2wd mode, but come on if pushed into Auto 4wd. Since my truck didnt have a warranty anyway(bought it wrecked and rebuilt) we tried tinkering a bit but didnt see anything wrong with the 4wd hardware. any ideas on what is causing this on 2 different trucks? (my dads was bought brand new off the lot, as i said before mine is a rebuild, so i doubt it was something in the rebuild process)

thanks

[joxx12]

Originally Posted by 99backinblack

Hey just wondering if you all are having the same issue as me and my father who both have 99's (mines GMC and his is chevy Z71s) anyways, we both have push button 4WD and in both trucks after about 60 k miles we started getting the service 4wd light come on in the message center, and the lights on the push buttons either dim or go off completly when set in 2wd mode, but come on if pushed into Auto 4wd. Since my truck didnt have a warranty anyway(bought it wrecked and rebuilt) we tried tinkering a bit but didnt see anything wrong with the 4wd hardware. any ideas on what is causing this on 2 different trucks? (my dads was bought brand new off the lot, as i said before mine is a rebuild, so i doubt it was something in the rebuild process)

thanks

I took my '01 Sierra in for that and they replaced the 4wd button module. I have an extended warranty so I only paid the $100 deductible for it and to have the steering column lubed. I think it would have been $250 for both without the deductible.

Later

[CoreyW]

Glad I found this forum. Hopefully it will help me out in solving the knock. I read on this thread and many people are saying this is normal. Honestly this is scaring the bejesus out of me. I have a 2000 v6 Chevy Silverado Short bed with 89k miles on it. It just started after I changed oil. Took it back to the people who changed my oil they changed the oil filter to a AC Delco oil filter. Didnt help. This is just about everytime I start the vehicle. Cold or warm. Its downright embarrassing. Yea so ford is laughing next to me on the road. Pffft whats up with that... The Oil pressure races up to 80 pounds (thats max) then after the knocked subsides it idles around 40 - 70 pounds. I honestly hope its truely nothing serious such as the engine crack or something to that affect.

Are there any fixes solutions that have worked that you guys have tried out yet?

Thanks Corey

[williecumminer]

Originally Posted by CoreyW

Glad I found this forum. Hopefully it will help me out in solving the knock. I read on this thread and many people are saying this is normal. Honestly this is scaring the bejesus out of me. I have a 2000 v6 Chevy Silverado Short bed with 89k miles on it. It just started after I changed oil. Took it back to the people who changed my oil they changed the oil filter to a AC Delco oil filter. Didnt help. This is just about everytime I start the vehicle. Cold or warm. Its downright embarrassing. Yea so ford is laughing next to me on the road. Pffft whats up with that... The Oil pressure races up to 80 pounds (thats max) then after the knocked subsides it idles around 40 - 70 pounds. I honestly hope its truely nothing serious such as the engine crack or something to that affect.

Are there any fixes solutions that have worked that you guys have tried out yet?

Thanks Corey

at cold temperatures a 4.3 has about 65-75 psi. as for your knock, there are no common problems i have run into, i have seen these engines blow intake gaskets and leak coolant internally into the engine. the coolant travels the pushrod to the lifter causing a tapping noise. i have seen this in a few 4.3's and a 454. have you had to add coolant and or is it low?

[mntahoe]

I haven't personally had any trouble with knocking, spark or otherwise, at over 135K. I'm running 87 octane. My general rule when building an engine is 10 octane points for every 1 point of compression. Things like fuel injection, cold air, aluminum and/or high swirl heads all decrease the octane requirement. Last time I heard, Nascar motors were running 15 or 16:1 on 110 octane.
One possibility I haven't seen discussed is piston slap. Chevy pistons can be installed backwards which offsets the connecting rod a little and frees up some horsepower by changing the rod angle. The draw back is that it causes the pistons to rock in the bores when its cold. It burns a little oil and makes a knocking sound sort of like forged pistons, but it usually goes away by the time you get up to temp.

[DeanHensler]

Originally Posted by mntahoe

One possibility I haven't seen discussed is piston slap. Chevy pistons can be installed backwards which offsets the connecting rod a little and frees up some horsepower by changing the rod angle. The draw back is that it causes the pistons to rock in the bores when its cold. It burns a little oil and makes a knocking sound sort of like forged pistons, but it usually goes away by the time you get up to temp.

My 2003 GMC 2500HD has an 8.1 Liter Big Block. I have Piston Slap really bad when I first start it. Goes away after about 2 minutes. Dealership said "There are no service annoncements about this." Basically told me to shove it up my ass and don't bother them. Also burns oil, but big blocks do that a lot anyways.

[burn0uts0n]

I as well have had the dreded piston slap in my truck as well. Of couse being from ohio, and the cold is REALLY cold in the winter time and they had said that the cold is what makes it worse. now correct me if im wrong, but the piston slap problem was covered in the 04 4.8's as well, wernt they? i talked to one of the guy at my local chevy dealer and they had told me that my motor has that "problem", but said that it will not damage or cause any other problems with the motor. I find this hard to belive, but thats what ive been told. the slap goes on and on until the termitate goes up to about a quarter. then it dies off. ive tryed everything to get rid of the problem too. high octaine gas, fuel additives, oil treatment, almost everything, barring taring the whole motor apart and messing with the piston itself. just was wonder if anyone else with an 04 4.8 has this problem too.

[mntahoe]

I'm told that it doesn't hurt the motor. I've never been brave enough to try it myself, but a lot of engine builders do it on purpose for the horsepower gains. Its easy to do by accident, and if you don't catch it on final inspection the only way to correct it is to tear the motor down. Chevy's no tlikely to do that until someone proves that its damaging the motor.

[N0DIH]

Originally Posted by PeteChevySales

Piston-slap happens on NEW 5.3 V-8's. As I am frequently the first salesperson at the dealership in the early morn I move a blocker (generally an Avalanche or Silverado or Suburban) out of the way for the day's traffic. If it's even slightly cool (that's low 70's for us so-cal folk) I've heard the snap-snap-snap of slap at start-up.
I wouldn't call it a Problem so much as an Annoyance, but then again I don't own one. The little 3.1 V-6 in the Buick Century does the same thing. Call it a quirk or call it poor engineering. Even if it doesn't actually cause damage, it causes distress on the part of the vehicle owner. That makes it a problem. Period.
Wondering whether or not your engine is going to sound like a typewriter in a kettle drum when you start it can make some reluctant to purchase. GM has a way to go as far as aural stimulation at start-up.

My thoughts are GM was pulling out the stops for fuel economy and loosened up the tolerances, at the expense of startup knock by the time production line tolerances and tolerance stackup have happened. You get a block that is on the loose side, a piston on the small side, what happens? Knock till it warms up or gets more oil in there to lube it up. Consider the worst case tolerances. Block with a 4" bore, max, min, -40F, +250F, the piston at the same temps, the blocks with mass production boring/honing tolerances, and again the piston from the piston manufacturer with their tolerances. Now, add in tighter tolerances and it adds to the production costs, so if they can use lower grade materials or be a little looser on not mandate 100% inspection of every clearance, you get slop out the door. Should GM being doing better? Yes, they should, they have enough experience to know better. FWIW, I would be surprised if after 2004 it still happens with all the bad press on it...

Again, my $0.02

[digthis]

Hello.
I have a 2002 tahoe lt 5.3l v-8 {327}? that had 35.000 miles when purchased, it now has 59,000 miles, It has had a csk {cold start knock} since we bought it, this would last about 2 to 3 minutes in the a.m, WE didn't think it was much of a problem just what it is, but since we went on vacation this past week to my brother-in-laws house he heard the csk and said it sounded like a lifter collapsing. So when I got back home I took the vehicle to my local Chevy dealer and told them to crank it in the a.m.,they said it was a csk and that the probable cause was carbon build-up and such, which if we wanted it fixed would be our call and our money, I didn't agree with this, simply because it csk'd all this time and I didn't consider it to be a wear and tear problem so I should't have to pay for it! so I went online and found this forum, which provided me with info on solving this problem, And yes I did get a 6yr, 100,000 mile warranty on my engine, I was so happy about this that I didn't really ask if this was above and beyond the extended warranty that I have or up to 100,000 miles period. I didn't ask if there was a deductable and what it was, I did ask if ti was transferable and the service rep said yes, so my question is did anybody ask these questions and get answers? If not I'll call gm back and ask them! tia digthis

[DeanHensler]

Originally Posted by digthis

so I went online and found this forum, which provided me with info on solving this problem, And yes I did get a 6yr, 100,000 mile warranty on my engine, I was so happy about this that I didn't really ask if this was above and beyond the extended warranty that I have or up to 100,000 miles period. I didn't ask if there was a deductable and what it was, I did ask if ti was transferable and the service rep said yes, so my question is did anybody ask these questions and get answers? If not I'll call gm back and ask them! tia digthis

How did you go about getting the 100,000 engine warranty? I've got a 2003HD with the 8100 motor. It slaps like a Diesel every morning! I would love a 100,000 warranty.

[sin]

Originally Posted by DeanHensler

How did you go about getting the 100,000 engine warranty? I've got a 2003HD with the 8100 motor. It slaps like a Diesel every morning! I would love a 100,000 warranty.

Call this number and complain. 1-800-222-1020

[4MYBOYZ]

2000 Silverado, 5.3 V8. I hear the "slap" every morning. I also had my service 4WD light come on while I was on my second test drive before buying my truck. I took it to the Chevy dealer and they replaced the 4WD button module (at the seller's expense).

I also hear the "slap" every morning I start my truck.

[djorijun]

So i have the same problem with the knocking, well i just called Chevy and they said since I am still covered under the warranty that i will still be ok if it gets worse, so they didn't give me the extended warranty.

[sin]

Originally Posted by djorijun

So i have the same problem with the knocking, well i just called Chevy and they said since I am still covered under the warranty that i will still be ok if it gets worse, so they didn't give me the extended warranty.

I am still under warranty and they gave it to me

[baggedepicurean]

I work at a dealership also, and a couple of 99 denali's with the 5.7 lt does the same knock/knock/knock when first cranking, and so does my 99 denali, but oil pressure fine, and it does quit, anoying as hell though

[TakkoTime]

Hmmm.. This has been really helpful; I have a 1998 ex cab stepside Z71 with the 5.7.. had it since new. After about 15,000 km it got a horrid knock when you start it until the temp comes up. My local dealer just brushed me off and said it was normal and within specifications... anyone else have problems with a pre '99? the 99 denali would be similar to mine but the tahoes and subs have roller rockers and a few other diferences... anyone else out there?

-Takko
(I'm probably screwed anyway, I've got over 150,000 clicks on the motor.)