like the title says, the motor is a rods and pistons lsvtec. the bearings were within spec and i cant figure this out! a friend told me it might be dry start up but i had an engine do this before and was fine until i over revved it. please help this is frustrating me

 

bump

 

Did you replace the oil pump when you built the motor? Has it always done this or is it a new problem?

 

rod bearing failure... IMO

 

I bought a oil pump that had 10k on it and cleaned it out. it just started doing this about a week ago. I just also changed to oil and there was no metal on my magnetic drain plug. It did not make that sound after i changed to oil but the next day it did. It only does this until the light goes off and runs perfect.

 

sounds like a spun rod bearing.

 

cut the filter open and inspect. also the check valve in the pump can be going bad.

 

Unhook the light and see if the noise goes away.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DonF &raquo;</TD></TR><TR><TD CLASS="quote">Unhook the light and see if the noise goes away. </TD></TR></TABLE>

LOL.......nice

 

you say the bearing are within spec? is this at time of engine assembly or did you actually pull the oil pan off and check them after you abused the crap out of it?

the specs at time of engine assembly will change when you overheat/spin or flatten a bearing.

pull your oil pan and check the mains and rods.

 

I plan on tearing it down soon. I still dont understand why it only does it when its cold? That part doesn't make sense.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mar778c &raquo;</TD></TR><TR><TD CLASS="quote">sounds like a spun rod bearing.</TD></TR></TABLE>

x2. I had the same problem, only made that sound at start-up. Pulled my oil pan and half of my bearing was sitting in it.

 

i had that same problem with an ls when i tore it apart the bottom end was in perfect condition

 

That is what i am thinking. A friend of mine that has been a professional mechanic for several years and he said that it sounds like the bearings are dry on start up and that it is nothing to worry about but i have some money wrapped up in this thing and don't want it blowing up on me.

 

the knock seems to have gone away.? i replaced my pcv and tightened my timing belt and it has seemed to stopped.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LS AzZkIkr &raquo;</TD></TR><TR><TD CLASS="quote">he said that it sounds like the bearings are dry on start up and that it is nothing to worry about </TD></TR></TABLE>

that statement worries me.

 

It only started making this noise after you changed your oil? What kind of oil are you running?