ok check it out:

every single time i drive the car, after about 3 miles or so i will lose oil pressure to a few of my lifters, and if i pull over and let it idle i can hear a soft knock in the bottom end until i either keep driving or let it idle until it regains oil pressure and runs perfectly for the remainder of the trip regardless if it's 5 minutes or 20 hours.

keep in mind, the engine has less than 20k miles on it. whenever this happens, the oil pressure barely drops below 40psi. it's normally just a hair over 40. i've seen these engines run perfectly with as low as 20psi.

it's starting to **** me off. i would say"oil pump" if it actually lost oil pressure on the gauge. i would say "lifter" if i didnt hear a knock on the bottom end

so at this point i think i have a clogged oil passage somewhere which pisses me off because i'm not quite ready to build my new engine. not to mention, it's pretty embarassing driving around with a loud *** lifter half the time.

any similar stories?

 

quick questions... how do you know its losing oil pressure to a few of your lifters...?

does the knocking noise only happen when the engine is cold or is it also present when the engine is Hot?

also, do your gauges reflect this "loss of oil pressure" that you think you are having?

 

it doesnt matter if it's a cold start or a warm start after sitting for half an hour. the oil gauge normally rides just above 40. when this episode occurs, it's still maybe 1 or 2 lbs below 40psi.

 

does the noise still occur when you stop the car for less than 30 seconds or only if its sat for a little bit?

also.. can you pinpoint exactly where you hear the noise from?

 

if i kill the engine WHILE it's doing it and let it sit for half an hour or so, it still does it when i start it back up.

 

and it sounds like it's from the left head.

 

thats not what I'm asking...

when the engine is fully warm, and the noise has stopped, and you have been driving for a while.....
if you stop the engine(say to run into a gas station for a quick bottle of your favorite fizzy drink) and you come back out...does the noise come back or is it gone? engine has been off for less than 2 minutes in my example

 

once it's gone, it's gone unless it sits for at least a half hour. as long as it stays within OT it doesnt come back.

 

sounds like common piston knock... sound goes away once everything is up to full temperature..
being a built engine, you may have one cylinder that is just a little loose fitting...especially if your builder had to hand file rings to fit.
you can try using a little thicker oil if you arent already... maybe a 10w30 or a 20w50 instead of a 5w30
also run a petroleum/mineral oil instead of a syntheic as well and see if it goes away.

you can double check for oiling issues pretty easily... just pull the valve covers off.. do a little creative dangle of the spark plug coil packs, and you can use a little sheet of plastic as a deflector for splashing oil... a 2nd and 3rd set set of hands makes it easier, but it can be done one side at a time..
if you have an oiling issue, you will see it pretty immediately, it will be obvious with the lack of oil coming up on the pushrods if there is an issue.

 

it's definitely not piston slap or a bad piston. i'm 100% sure it's lacking oil to certain parts of the engine without actually losing oil pressure at the oil pump. i'm just stumped as to why.

 

thats fine if you dont want to agree with my opinion...

but I highly doubt its an oiling issue as you think it is...
oil issues dont dissappear with heat, they will be there all the time no matter what.usually oiling issues get worse with heat...

the only things that make a noise when cold and not when hot are pieces that expand..... pistons and rings expand enough to make noises and then get quiet with with temperature changes.

 

i know. that's why i'm stumped. is there any way the oil pump could be worn out, but it still still showed good pressure on the gauge????

 

i'll take it out in the morning and get a video when it starts doing it.

 

ok maybe this will help. the enigne was from a junkyard. before i installed the engine i installed my old TR224 cam using all my old accessories from the LS1 including hte pickup tube and oil pan. it did the same thing it's doing now for like a month. then it stopped for an entire year and worked perfectly. it even made a trip to texas and back (3000 miles total). then i installed the LSR cam i have now. then the issue started all over again. and in the past few days it has started to do it EVERY time i drive it. at first it was maybe twice a week. also there's a noise coming from the bottom front of the engine that sounds like a procharger. it sounds like the timing chain is scraping against something although it's not because i did all my own work.

 

put a screwdriver to your ear and against the front cover... that will tell you if its the timing chain or something up front making noise...

I still say piston slap.. especially if its a junkyard block... well known problem in stock ls and lq engines..
could be a worn ring or a cylinder out of round...
both can come and go over time as things wear in or wear out.

the "procharger" noise is probably a pulley going bad or getting worn... possibly something not sitting quite square...
alternators make that noise, the middle belt small pulley will make that sound... hell I had one that made that noise for 4 months solid on an old setup.. I ended up having to spray it with silicone about once a month

 

i can see why you think it's piston slap, but it's a totally different sound. it doesnt do it right away after i start it like piston slap does. it doenst occur until sometimes 6 minutes into the cruise. then go away after like 3 or 4 minutes. loud *** lifter tap. i planned on putting my pry bar and ear against the front cover to see if something is contacting inside. i'm about to tear it down to build 4.1" stroke 427 though, and i have 2 other vehicles, so i'm not that worried about it. i'm just stumped and it's destroying my brain trying to figure it out.

 

It sounds like you may have a bad oring at the oil pump. It will sound just as you describe. Try adding 1QT of Rislone to the oil then see if it changes. I had a very similar thing going on with my car that basicly sat for 5 years without being run. Everytime you shut it off for while OR if i changed the oil filter it would tap and hammer and click so bad it was BAD!. It was definitely the lifters and valves making noise. I was sure the oring was shrunk from sitting and bleeding air into the system because although the pressure was 40+ at idle it would act funny when revving the engine. Kinda not rise with rpms right away like it should, It would be slow to rise and then hang high. I've been using 1QT of rislone every oil change and all the trouble went away. I think the Rislone swelled the oil ring. I still have terribl piston slap cold but that goes away after it gets hot, the noise you are talking ablout is a clicking clattering sound that sounds high in the engine. Although i've heard some crazy piston slap in these engines I believe you are not descibing that . The dealer service depts love to use the piston slap noise excuse to get away with lifter noises.

I had bad lifter noise in my other LS1 after the body shop gad the car for a few weeks, I guess they beat the snot out of it. I took it to the dealer to get it looked at and the head wrench TRIED to blame it on piston slap. I sgot into a big argument with him about it because it was clicking and tapping and not knocking like a diesel. Luckily after a few 100 miles the lifters bled out and stopped making noise. These crappy factory lifters collapse if you rev them high and then until the air works its was out you get clicking and tapping IF you are lucky...if not the collapsed lifter breaks from being hammered to death by the cam.
The air that gets mixed with the oil causes the lifters to colapse and clatter. Sorry for the poor spelling grammar but its like 3 in the morning and i'm not in the best mood to type any kind of **** about lifters cause these ls1 lifters are really a PITA to deal with and are pissing me off. I go WOT I get lifter tap for the next few starts until the lifters bleed out again....THANKS GM.



every single time i drive the car, after about 3 miles or so i will lose oil pressure to a few of my lifters, and if i pull over and let it idle i can hear a soft knock in the bottom end until i either keep driving or let it idle until it regains oil pressure and runs perfectly for the remainder of the trip regardless if it's 5 minutes or 20 hours. <<<<<<<that is CLASSIC air in the lifters.