tashspop

iTrader: (1)

i was doing some logging to dial in my maf and right after the pull i noticed a knocking or loud tapping sound. i'm really hoping its in the top end. but as loud as it is idk. motor has oil pressure, no change in how it runs that i'm awair of since i babied it back to the house. no smoke either. my log says i shifted at 6400 rpm.

here is a video of it after setting 20 min.
Lq4 sounds bad - YouTube

AKlowriderZ71

iTrader: (22)

Sounds like a broken piston, but it's hard to tell for sure from a video.

Interested to see what you find. When are you gonna teardown?

tashspop

iTrader: (1)

i dont know, my knuckles don't what to start in this cold front. i have work tomorrow so it'll probably start during thanks giving break. i really don't want to pull the motor out. i just got that transmission in there, and i'm still paying on it.

tashspop

iTrader: (1)

just incase i just pick up a different engine to go in there, i see lq4's listed from 2001-02 and septeratly 2003-up. what is the difference? would say a 05 drop right in? i know i've read the connecting rods got better at some point that that won't effect it replacing mine.

tashspop

iTrader: (1)

i still haven't had the time to look at my truck, but after doing some searching on here i've discovered alot of people have had issues with the flywheel or flexplate breaking. anybody with that experience think thats what i could be looking at?

while driving i pulled onto a road and once i got straight i rolled into the throttle until i was all the way into it. it was the first time i actually got all the way into it without completely smoking the tires while in first. second gear hit hard which usually breaks the tire loose pretty good, but this pull the truck lunged forward and thats when i backed off the gas and began hearing the knocking noise as rpm's came down. also, i don't recall the knocking changing pace directly with engine speed. but i had so many things going through my mind on my way back home the details of what i heard may be off.

my transmission hits second gear really hard so i'm hoping all i did is find my weak link. the engine is also on solid mounts.

Platinum WS6

iTrader: (6)

I would first pull the valve covers off and check all of your valve springs to make sure everything is in tact. Last time I had that type experience was in my TA after a nitrous pull. It bent a valve pretty bad but didn't damage the piston too bad. Check there and if your valvetrain is ok then you probably have bottom end issues.

tashspop

iTrader: (1)

i forgot to add that i pulled each plug wire off the passerger side with motor running and the tap noise did not change.

so what all should i check with valve covers off? i pulled it and it looked good to me, and only got a little side play on two rockers that were down in that motor position.


i also uploaded a little better video.
Lq4 tapping - YouTube

if i need to look at my lower end, is it pretty easy to pull pan off with motor in truck? just looking around, it looks like it can be done easy. i don't have a cherry picker here at the house so i'd rather not pull the motor unless i have to. Or should i remove the head on that side to look at the pistons?

i did check out my flex plate the best i could with only removing the starter. i couldn't see any issues so idk if i need to pull the trans yet to get a better look.


here is the beater

skeet

iTrader: (18)

since there no dust cover id get an inspection mirror and flashlight and check the converter bolts. if all look good then i'd pull the pan

Mangled03gmc

iTrader: (95)

Do a compression test would be next on my list, then as said possibly check the converter bolts, FP. Doesn't sound like a rod knock to me, but then again its only a vid.

tashspop

iTrader: (1)

i do have a compression gauge burried in garage somewhere, i'll go hunt that down.

converter bolts are easy to check too.