TSB scan of 4.3 balance shaft noise

Jim · Post by **Jim** » Mon Nov 18, 2002 4:28 pm

http://www.nhtsa.dot.gov/TSBScans/sb628938.pdf

The rattling sound they describe has been driving me nuts since new... finally it has been recognized.

AZS10Crew · Post by **AZS10Crew** » Mon Nov 18, 2002 5:01 pm

I think my 2003 might have that too. Is it kind of a vibration type of thing in the middle RPM range? Mine seems to be doing something like that. I figured it was just a thing with the enginge not being broken in yet or something. I guess it's not a serious problem, so i'll just have to get used to it I suppose.

a2b · Post by **a2b** » Mon Nov 18, 2002 10:06 pm

i am not quite sure if i hear the same noise. but i hear alot of noises. my a/c makes hella noise. but i do hear the same rattle sound that i used to hear in my 1989 4.3 chevy. pre vortec years. i have lots of other clunks too.

Conman · Post by **Conman** » Thu Nov 21, 2002 8:33 am

I think someone brought this up at the old forum. So far I don't have the noise but I only have 2,700 miles on the Crew.

Cheers,

Con

Jim · Post by **Jim** » Thu Nov 21, 2002 2:55 pm

If you don't have it when new you may be lucky.

My theory is there is no adjustment in the gear clearance the noise is worse when the engine is run & let cool a little, then run again. I think it has to do with the machining & expansion of the block. You can't hear it on the outside...with the window down you don't hear it. But windows closed no heater fan or radio on you may, it's a faint rattle under acceleration from the fire wall area. The one I test drove had it & mine had it @ 50 mi. A good way to rule out detonation is fuel octane low grade or high grade same noise...ballance shaft

.

I don't understand why the valve train on all the ones I have heard is noisy also. The 5.7 V8s were always quiet & all the 4.3s are is the 5.7 V8 missing two cylinders.

AZS10Crew · Post by **AZS10Crew** » Thu Nov 21, 2002 5:15 pm

My LS1 in my Z28 always had lots of valvetrain noise...especially during warm up. It wasn't too bad once it was warm, but when cold, combined with the nasty pinging when it was cold, it sounded horrible! But like I said, once it warmed up, it was pretty smooth and quiet.

Post by **HenryJ** » Thu Nov 21, 2002 6:18 pm

Lots of the early Hi-po engines sounded more like a diesel than gas engine, I though with all that piston slap they'd switch holes when cold.

Soild lift cams, anti-pump up lifters, forged pistons all had to have bigger clearances to allow for expansion. The newer alloys and designs allow for closer clearances and less rattle when cold.

So, I guess if ours rattle a bit we can just be a bit nostalgic, and imagine it is an LT1 under the hood