Well the # 6 bearing i beleive took a **** on me yesterday,now this is the the third #6 or 5 that has gone on me in 3 motors. First motor had 78,000 on it when it went so i obught another 52,000 motor and put in a S1x,springs,retainers,pems,plugs and wires on and in it while i had it out(2nd motor) b4 i put it in the car,well 20 mins later after i got that one runnning the # 6 bearing spoun as well i thoight i narrowed the problem down to a stuck valve in the timing cover…so i bought another motor with 50,000 on it and proceeded to throw evrything on and in it along with a oil pressure gauge and new timing cover(one that cam with 3rd motor). Now everything was running fine for a month excpet for my LTFT’s which were -13,so i went to my buddys house and he is selling his GTP(99) so i swaped PCM’s with him and took it for a ride(he had shift points increased) i got down the road and scanned the car at WOT and LFTF’S were at 0,so i turned around and BOOM! i hear that o so well sound of a spun bearing[][:@] Now here is what i have reused on my motor…fuel rails,coil packs and LIM,thats it! So i odn,t know whats going on here…anybody have any ideas? I am not sure what to do…either get a used motor and throw it in stock and sell or try my luck and do it all over again,any ideas on what could be causing this?[]
behind streering wheel
are you using drop in bottom ends or rebuilding them? … if they are just used shortblocks or longblocks?
wtf is a LIM?
Using used motors52,000 and 50,000 miles ones,and a LIM is Lower Intake Manifold
you for sure this is a spun bearing? if i’m reading your post right you’re saying because your LTFTs were messed up and you heard a boom that it’s a spun bearing…
infortunatly yes…spun a bearing,i know what the sound is unfortunatly:(
Damn, sorry to hear that. Is it possible that the mods you have just aren’t friendly to a stock bottom end? Are other guys with similar mods having spun bearing problems? Seems to be a similar thing with LT1s with heads/cam done to them.
spun bearings dont boom i thought…More like a knocking noise!!!
Stock bottom end should be able to handle upwards of 400 HP,so i don,t know,i have afew people telling me that it could be the PCM making me spin them consistantly
unles you’re knocking to the point you’re putting extra stress on the bearings it’s nothing in the tune that’s going to spin them. it’s either tolorances from the factory, the crank is walking within the caps, or a lubrication problem
no knock,PCM could be adjusting itming wrogn if thats what it actually is.
if it was adjusting timing to put that kind of stress on the bearings you would see knock, as it would be trying to push the piston down as it’s still traveling up.
The car was running rather sluggish,not what it hsoulda been running for the past month if that means anything. If it was the oil prob or fuel then y wouldn,t it of happened earlier,not a month later and about 1200 miles later,seems weird that i tried another pcm then it happened but could just be coincidence and due to 6300 rpm shift point from tha9t PCM,but who knows…
You will burn a whole in the piston before knocking a bearing loose with excessive knock. Most likely it is mechanical, and a lot of bad luck.
heres a thought…
3 motors all with same mileage and same run time with new setup…
all with a cam installed, cam might be fucked up where its killing bearings
First motor…79,000 and no cam…spun bearing
Second motor…52,000 mile with cam and 20 min run time…spun bearing
Third motor…50,000 miles with cam and 1 month run time and about 1,200 miles on it…spun bearing.
So with the first motor and no cam i don,t think it is the cam quik.
this is the person that was making fun of me for going threw 3 motors in one summer telling me my shit was junk…
but anyway what is the stock redline? and are you taking it past that, the main reason for spun rod bearing is stretching the rod bolts, becuase these motors are put together by gm and have ran for 50,000+ i am sure the tolerence(s) are ok…a few of my ls’s spun rod bearing cause i was spining them to 7600 not 7000 witch it was designed for (holding 4th to go threw the traps)
good luck
LOL,y ai made fun of u but all in FUN,as far as the redline goes…my PCM was set at 6000,his was set at 6300 becasue it is for our cams.
its either that or you have an oil issue not getting to those rods.
this one time i went to the track. ran fine drove it home. then the next morning when i fired it up it was knocking…where you beating on it before or when it started the rod knock
Aactually i had his PCM in at that time and too kup to 6300 RPM b4 this happened,took it up to those rpm,s once or twice then turned around and drove it slow then came the dredded knock.