VTC_WS6

iTrader: (9)

You know I thought when I made the leap from Honda's to F-body's my luck would change.. guess the black cloud of death lingers for me

So my wife and I take the Firechicken up to the track yesterday to enjoy the Nopi event, my wife goes ahead and enters herself in the open bracket class to get some practice in while I sit back and enjoy the afternoon. She takes a couple passes, runs pretty well for the 150* heat heh, and after the second run she parks it and I decided to make a small change to the map on the car. After making the the change, I restart it, all is well, give the car a couple of quick revs and there it was on the deceleration ...*knock-knock-knock*!

I could just about kill myself.

Sure enough, holding the motor at about 1500rpm will produce a light to medium knocking sound, consistently. I look at the oil pressure gauge and also notice a lack of pressure, holding around 30-35psi vs. the usual 40psi (warm), and what was even more interesting was that if you watched the needle carefully, you could actually see is flutter as the car sat and idled. Let the car sit and cool down and give it another shot, oil pressure build up immediatley on start up but to only ~40psi (usual for cold start is about 60psi), motor doesn't knock right away, infact it didn't knock for at least a minute or two, but as I gently raised the revs, there it went quietley knocking again at around 2k rpm.

Thankfully I was able to drive the car all the way from West Palm Beach to Miami (~100mi) after adding some cheapo super thick 15W-50 oil, 1400rpm/60mph all the way home, never really heard the knock but every now and again at idle you'd hear the quiet tapping again.

So, prognosis anyone? I'm thinking I somehow stretched a pair of rod bolts and a cap has come loose, I can't imagine how the car would just randomly spin a bearing for no reason, epsecally with how well this car is upkept. Lastly it was suggested to me that it might have been a pushrod but I doubt that since the sound fluctuates with rpm and time, whereas a bent pushrod would leave alot of play between the rocker all the time. Any input would be apprieciated.

*sigh* My first major LS1 letdown..

VTC_WS6

iTrader: (9)

Bump.. anybody?

OUTLAWZ RACING

iTrader: (9)

How Many Miles On The Car What Type Of Oil Any Power Adders???
Ls1 Valve Trains Do Make Noise On A Cold Motor And Even If It Sat For An Hour O So I Bought Mine Brand New In 02 And The Next Morning It Sounded Like A Fkin Disel It Was About 45 Degress Out From What I Read Befor I Bought The Car Is To Allow It To Warm Up Befor I Go And Use Castrol Gtx 10w30 3cans And 20w50 3 Cans Been Doing It Since And Car Dosent Eat Oil With 40000 On The Clock

OUTLAWZ RACING

iTrader: (9)

Non Synthic Fk That Sht

VTC_WS6

iTrader: (9)

Mods are in the sig, it's a bolt-on car, nothing out of this world, reved to 6200rpm at the highest.

98A4LS1

iTrader: (1)

I don't think stock LS1 engines can handle repeated high RPM's, racing, etc. You see this kind of post/thread all the time it seems like.

stevewix

sounds like a spun bearing lets hope it's not though.

VTC_WS6

iTrader: (9)

My LS1 only saw high rpm during a race, which would be for what.. 12-15 seconds of WOT at a time? Mind you I drive it like grandma when I'm not racing, the car sees nothing but Mobil1 since I've owned it, and it only makes 356whp on bolt-ons. Just very odd to spin a bearing on such a simple setup..

Just as an update: I went ahead and started the car this evening to move it into the garage. Started right up, instant oil pressure albeit lower than usual (normal cold pressue is 60psi, started up with just over 40psi). No unusual sounds, no misfire, let the car idle for maybe 30 seconds when I gently played with the throttle cable, no sounds as the revs increased, finally after about 2 mintues of idling I got it to make the knocking sound again but it's somewhat elusive, it comes and goes as opposed to being a constant. Oil pressure still holding around 40psi but the needle is flickering telling me the car is losing pressure somewhere. I've narrowed it down to (1) Spun bearing, (2) loose rod cap/stretched rod bolts or (3) bent pushrod.

Anybody esle wanna take a stab?

freakynipples69

iTrader: (3)

and I thought it could. Welcome aboard the wagon.

Kennedy98z28

iTrader: (3)

I spun one Sat. at the track.

patSS/00

iTrader: (6)

You do know about the reputation of the oil pumps right? Earlier years can go bad due to stuck pressure relief valve. Also you should diagnose noises when the engine is fully hot. You can even get noise from uneven cool down of parts due to car sitting for 20 minutes.
I like that 10w30 + 20w50 idea, think I'll try that next time.

MAC4264

Your rod bolts are not loose, If they were you would have known by now. You would not have made that 100 mile trip. If you think it is a bent pushrod the noise will come from one side or the other, in most cases. If you determine it is on one side pull the valve cover and pull the rockers and check. If the noise sounds deep, get ready because it gets deep. I saw many LT1 s with spun or worn bearings at the same mileage (they have the exact same rod bearings). These motors are some of the best in the world but they are only metal and can only do so much.

Moparnos (The SLP Guy)

iTrader: (55)

nice title

strokedls1

iTrader: (1)

Sounds like a spun bearing. Dump your oil and check for metal shavings. May want to cut open the filter to see what it looks like also.

VTC_WS6

iTrader: (9)

I don't see why not. If the bearing seized it would've progressivley torn away at the crank further opening the distance between the bearing surface at the crank surface, surley in a 100mi trip you'd think it's make a more pronounced sound. Also keep in mind that the sound is 'come-and-go', it's not a constant, this is what has be thinking it's a loose cap, but hey who knows, at this point it could be just about anything. I'll pull the rockers tomorrow and check the pushrods for the hell of it, something tells me this isn't going to be pretty

It's a 350whp bolt on motor making a couple passes at the track, I think it's safe to say I'm not asking alot of the motor, at least no more than the vast majority of folks on here do.

Turo

iTrader: (23)

I would first drain the oil and look for shavings. If its clean, then pull the valve covers and rockers, and start checking the pushrods. Both of those things can be done in an afternoon and it will help you noarrow it down. Good luck!

magius231

iTrader: (8)

a loose rod bolt would definitely not be coming and going, and probably would have shed your rods long before 100 miles were up. Look elsewhere IMO, valvetrain, oil pump, etc. Cutting open your filter and checking your oil would be a good idea to eliminate a spun bearing

BRIAN98Z28

sorry to say bro, im about POSITIVE you spun a bearing....your situation is an EXACT replication of what happened in my 98.....im talkin' to a "T".

bulletLS1

definetelly spun bearing.
be prepared... if you want to fix it (you should!)
before is too late for the crank, well I mean since you pampered may be possible to remove the crank and just polish the journals and get away with STD bearings.
and BUY ARP ROD BOLTS!!!!!
I broke a rod on startup, (the force of the starter broke it) and postmortem analysis showed a streched rod bolt.
unfortunatelly the spare list can be hefty:
gasket set
rod and main bearings (RACE!) no mater if you are grandma-driver is well worth the expense
bolts for mains you have to buy NEW. ( no mater if OEM or ARP)
rod bolts ARP, with my eyes closed, the OEM crap is the culprit.... (I sleep better now)
port, polished, AND shimmed oil pump
LS2 timing chain

in the engine shop

ask for a hot tanking of the oil pan, is well worth the efort because of metal shavings.

GOOD LUCK

PS: my mother is a grandma, has a 4.6 X5, and goes regularly to the beach AT NO LESS THAT 210KMH!!!!!

VTC_WS6

iTrader: (9)

How many miles did you have though? This just seems too sureal for a 50k mile car..