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?!
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?!
yeah it norm i have found out it is the dohc that is in the trailblazer and using a oil heavier then 5-w30 will make it louder. so no it not a problem it just a trailblazer thing
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.
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?
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?
I think my TB finally started having this problem, as it sounds like a diesel for the first little bit until it gets warm. I found that slowly pushing the pedal most of the way down makes it go away, and I will just run 1 up my hill.
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.
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.
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.
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
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.
yea, i remember seeing that when i was trying to locate the noise, just didnt think about it.
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