SonofaBish

iTrader: (5)

I put new heads on the car in early august, and for about the past month now, i've been noticing a noise that honestly sounds like the valves rattling. I think i've heard it in every gear, but i can make it happen (most notable) anytime i want if i'm under load, part throttle, in 5th or 6th gear (appx. 1500-2000rpms). First thing, i had never heard of the valves rattling on a LS1. Furthermore, if it starts to make that noise and i push the pedal to the floor, it quits. Same thing if i let up.... Any thoughts on what the deal is?

Slo_240sx

iTrader: (17)

Did you check PR length and replace the lifters? Might also be an exhaust leak.

SonofaBish

iTrader: (5)

brand new lifters in it... PR length could be the issue... i've thought of that, b/c i didn't check the length. It all seemed to be working with the stock heads on there, and when i put the 5.3's on, i didn't change PR's b/c i didnt see any need to.

i'm trying to rule out what it is hoping its either nothing major, or something to the effect of PR's,etc. She'll be getting torn down and parted out within the next month, in which all the things such as PR length, etc. will be checked to be exact for the new FI setup. I'm pretty positive its not an exhuaust leak.

thanks for the thoughts! you might be right

like the view?

sounds more like a lifter problem, i have the same sound from 1800-2200 rpm in my neon. Its a clicking noise, although i would deff check your pushrod length.

GuitsBoy

iTrader: (4)

I hate to ask a potentially obvious question, but are you sure its not pinging?

slow trap

iTrader: (22)

that's what i was thinking also.are you running 93 octane ? either way i would get something like a scanmaster and check it to see if that is what it is.

GuitsBoy

iTrader: (4)

Maybe try half a tank of 100 octane, or a gallon of xylene mixed in a tank full of 93. If it clears up, you know its a knock / detonation issue.

csmc711

iTrader: (4)

could be your tranny? Sometimes if you lug it too much the tranny will sound like that.

SonofaBish

iTrader: (5)

yes, i have never run anything but 93 or 94 in the car....
I suppose it could be knock or pinging b/c of the increase in compression, but why all of a sudden? And why woudl it go away at WOT? I'm not second-guessing your assumptions, just trying to understand why.

SonofaBish

iTrader: (5)

maybe i'll head to my tuner's place next weekend and have him run the diagnostics on it while we go up the road and see what it reads.

slow trap

iTrader: (22)

where it may or may not be spark knocking your timing table may be too high,why it just started is strange but it sounds like spark knock to me.with your tps at a different position like say wot your timing table will be different,probably 5 or more * less timing compared to part throttle so that would explain why it goes away at wot.it could be a lifter you hear but maybe your tuner will be able to fix your problem.

SonofaBish

iTrader: (5)

Ok thanks man!!!
Actually, now that you mention it, i actually do have a SES light that has to do with something like low voltage from the front knock sensor (i think i pinched a wire when putting the new heads on) Since the motor is getting torn down soon, i didnt really think much of it and i was told it probably wasnt a major deal so not to worry bout it for now....
Maybe that could be part of it to no? If it starts to knock and the sensor does read right, it won't retard the timing liek it should.

I will drop the tuner an email and see if we can fix it... If it is detonation, it will definitely show up on the diagnostic? or b/c the knock sensor does wanna work right, could that put me in a bit of a bind for figuring out the problem?