Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

Piston slap?!

16K views 12 replies 10 participants last post by  UpAndComing2k2 
#1 ·
I've noticed on my customer's 4.2 liter.. that when cold, the thing rattles like a diesel! Obviously, it's piston slap.. it goes away when the engine gets up to temp.. for the most part. Is this a problem that a lot of people are seeing on stock engines?!

Travis
 
#2 ·
Trav4011 said:
I've noticed on my customer's 4.2 liter.. that when cold, the thing rattles like a diesel! Obviously, it's piston slap.. it goes away when the engine gets up to temp.. for the most part. Is this a problem that a lot of people are seeing on stock engines?!

Travis
Whats the build date of the tb. I hope its not about to drop a sleeve.
 
#4 ·
using a oil heavier then 5-w30 will make it louder

Interesting... the exact opposite occured with mine. 5W-30 oil was noticeably noisier on cold start than 10W-30, so I use a conventional 10W-30 (which is OK as per the manual above 0°F) and it very quiet when cold. Built 11-01, no "piston slap" or other unusual mechanical noises here.
 
#5 ·
I always use 5w30 mobil1 in mine, and now that the winter is approaching, it seems everytime its been around 40 degrees overnight, i'm getting piston slap til the engine hits around 140-150, whenever the t-stat opens up. my build date is after the whole sleeve issue, but could that still be the problem?
 
#6 ·
Steve02SLT said:
I always use 5w30 mobil1 in mine, and now that the winter is approaching, it seems everytime its been around 40 degrees overnight, i'm getting piston slap til the engine hits around 140-150, whenever the t-stat opens up. my build date is after the whole sleeve issue, but could that still be the problem?
Mobil1 5-30 in the '03 SLT I had definitely made the engine run quieter.:yes: I'll be changing in my '05 to Mobil1 at next oil change.
 
#8 ·
Mine is slightly noisy when cold, esp. below 20F. It does sound a bit like a diesel until it warms up in a minute or two. I recently switched to Mobil 1 5W-30 and have to say it quieted things down a LOT.

GM's official stance is that the piston slap is not harmful to the engine's performance or reliability. Engines built after late Jan. 2003 have slightly modified pistons to reduce this noise. The updated pistons have a special coating and are slightly longer than the original design.
 
#10 ·
dmince said:
If it's annoying to you, have GM replace the pistons and rods. They did mine last fall with only 16k miles. It sounded like a diesel even when warmed up.
I would love to have GM do that, but with 56k and no warrenty, it wont happen until me engine blows. I know it is bad to say, but I actually want it to go so I can get a new one with the better pistons, etc of the 03+ models. Heck, I might even get them to replace it with the new 06 I6 that pushed 291hp instead of 270 (2002) or 275 (03-05). Also, all of the 03+ have like 5-7 more tq than the 02. 277 vs 270 I think.
 
#11 ·
i have that same thing, except it seems like it doesnt go completely away even when warm. I was thinking it could have been a valve or something (did not know anyting about the sleeve issue). I think a lot of the noise i hear when warm may be spark knock also, so i guess i need to check plugs/wires soon
 
#12 ·
UpAndComing2k2 said:
i have that same thing, except it seems like it doesnt go completely away even when warm. I was thinking it could have been a valve or something (did not know anyting about the sleeve issue). I think a lot of the noise i hear when warm may be spark knock also, so i guess i need to check plugs/wires soon
Just FYI, there are no plug wires on these engines (at least the 4.2L I6 doesnt have any, havent seen a V8 up close and personal), they use a coil-on-plug design. There is a seperate ignition pack on each of the spark plugs.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top