I'm getting a rattle which follows the engine RPM's and I throught I'd try a local resource before paying a dealer an hours worth of labor to tell me "the engine is modified, it could be anything". Anyone?

 

umm i could prolly listen to it for you, i cant promise anything.

 

Here's a video I made tonight...

video

Thanks!

 

i watched the vid , sounds like the noise is on bottom end but hard to tell ( pin point ) from the vid. if its bottom thats not good .

 

Could be bearings, could be loose flexplate bolts/cracked flexplate (if automatic) loose flywheel bolt(s).

 

Dude,
Poss lifter collapsed...
How many miles??? 100K or more???
I'm a "retired" Master GM Tech. Now work for GM Aftermarket Sales...

The GM dealer will take a GM Tech2 scaner, and do an injector balance.
IE:turn of one injector at a time, and see if it is the wrist pin / piston problem
Next remove the serp. drive belt, that will reduce the front of the engine noise...
If you want my EWAG (Educ. Wild As- Guess):
Lifter???
Dr.Phil

 

you can also take each plug wire off one at a time to check for a bad wrist pin

 

Yea.. But,
Pulling the IC wire, can "bite"
Have you been "Bit" by one???
It's Shocking...
Yes the spark plug pliers will work, but can tear the boot.
Thats why I have the "Proper" Tool
(I own a GM Tech 2 scanner)

 

yeah i got bit when i was like 14 lol learned real quick to not grab wire with bare hand but this is a very easy and quick way to check

 

pm sent

 

The odometer reads ~140K, but that's only on the chassis. This motor is about 2 years old. It's funny that a few of you mentioned the dealer diagnostic tools. I took it to the dealer and my normal tech said the noise sounded like it was coming from the right side and probably cam/lifter. Didn't perform any of the aforementioned tests, maybe because they know it's a built motor. But they didn't charge me anything to listen to it... just needed to pay for the 3-day car rental at their reduced rate.

Long story short, I'm building a LS3 to replace the LS1, and will part out the LS1 347. I toyed with buying a 4" crank, but that would put a serious hurting on my LS7 clutch I think. I don't want to put a big motor in and then find out I have to upgrade other expensive systems to keep it reliable.

 

Expensive you say .Think im going the same route on my 98z.