2008 Sieera Denali 6.2l

jbshoo · June 8, 2010

I just bought a 2008 Sierra Denali - 17K - the truck is in exceptional condition both inside and out. Thats the good news.. The bad news is that I have a cold start knock that I noticed on the first morning of driving (after the vehicle was cold). The knock which sounds much like a lifter noise was appearent when you started to drive - with minimal load on the engine. After the vehicle comes to temp (220) - noise is gone.

Is this worth a trip to the dealer? The vehicle is GM Certified for 12 months and I also bought the GM Major Guard - good till 90K.

Oil consumption so far less then 1000K miles since delivery appears to be zero. Being a car buff - the noise is driving me crazy (as I know something is not right).

Anyways - any guidance you can provide would be great.

Jeff

Stevens03 · June 8, 2010

Welcome to the site.. and most of these motors do it for a few seconds at start up.. if you think it's excessive.... I'd take it in for piece of mind.

Willshire · June 8, 2010

Welcome to the site.. and most of these motors do it for a few seconds at start up.. if you think it's excessive.... I'd take it in for piece of mind.

if its a tick it'll probably be lifters, although they are on roller rockers. If its a solid knock it could be piston slap (piston is .001-.002in smaller than bore) My truck has had piston slap since i bought it with 150k miles on it still runs great, no oil consumption. Piston slap is not damaging unless you have a heavy foot before it warms up (aluminum pistons expand at a greater rate than the block) I'd take it in to have it looked at for peace of mind.

jbshoo · June 11, 2010

Welcome to the site.. and most of these motors do it for a few seconds at start up.. if you think it's excessive.... I'd take it in for piece of mind.

if its a tick it'll probably be lifters, although they are on roller rockers. If its a solid knock it could be piston slap (piston is .001-.002in smaller than bore) My truck has had piston slap since i bought it with 150k miles on it still runs great, no oil consumption. Piston slap is not damaging unless you have a heavy foot before it warms up (aluminum pistons expand at a greater rate than the block) I'd take it in to have it looked at for peace of mind.

Thanks I stopped at the dealer today - they said the older models had noise, but I should not be having any - going in for service on Wednesday - hopefully they will fix.. I'll keep you posted..

jbshoo · June 17, 2010

Welcome to the site.. and most of these motors do it for a few seconds at start up.. if you think it's excessive.... I'd take it in for piece of mind.

if its a tick it'll probably be lifters, although they are on roller rockers. If its a solid knock it could be piston slap (piston is .001-.002in smaller than bore) My truck has had piston slap since i bought it with 150k miles on it still runs great, no oil consumption. Piston slap is not damaging unless you have a heavy foot before it warms up (aluminum pistons expand at a greater rate than the block) I'd take it in to have it looked at for peace of mind.

Thanks I stopped at the dealer today - they said the older models had noise, but I should not be having any - going in for service on Wednesday - hopefully they will fix.. I'll keep you posted..

Update - track has been at dealer for the past (3) days - problem appears to be piston related - they are tearing it down tommorow - I will let you know what they find - good thing for warranties! Anyone else having these problems??

foreverkidd · June 18, 2010

mine fires up and runs great from cold start. even in -40. next oil change, (30,xxx mi) i will be changing over to full synthetic with an oil stabilizer.

70gtorag · November 15, 2010

Jeff S.

Update - track has been at dealer for the past (3) days - problem appears to be piston related - they are tearing it down tommorow - I will let you know what they find - good thing for warranties! Anyone else having these problems??

What was the result?? My 2007 Denali 6.2 is the same problem. It was purchased through a dealer under the Optimum Vehicle program since it had less than 60,000km on the odometer. It is at the dealership today getting looked at for the noise.