BTLD_LS1

iTrader: (1)

Hey guys I'm having an issue with my car and I have 2 ideas of what it could be, but I'm looking to see if anyone else has experienced a similar issue.

Car is a 98 Z28 auto with a 98 LS1 built 6 years ago with under 3000 miles on it now .005 over with Manly pistons, Eagle rods, Eagle crank, bearings are H series bearings (new), single roller timing set Katech oil pump, Comp cam & spring kit etc.

Essentially about 6 months ago the car started making a random knocking sound at idle and there was noticeable play in the crankshaft so I figured the thrust bearing finally caved under the abuse. I let the car sit as I had other projects going and finally got around to working on it. I replaced the Main bearings as the thrust bearing was pretty torn up. and the rod bearings for good measure as I already had it apart(no noticeable damage with minimal wear)

Put everything back together and it is still making the noise. I took it for a short drive to get fuel and see how it ran an all seemed fine and the noise actually disappeared for the second half of the drive. However when I pulled in to the drive way the noise came back, only worse and the car will not idle now. If you bring the car off idle and have it anywhere over about 1250-1300 rpm the noise vanishes and you would never know there was any issue at all.

The only code currently being reported is a cam position sensor error which I have had since the motor was put together. At this point Im leaning towards either a cracked flex plate or an issue with the timing set. Has anyone run in to this or anything similar before???

remauto1187

iTrader: (1)

cracked flexplate and/or torque convertor bolt backing out. Ive had a torque convertor bolt back out and made the same noise situation you described.

S10xGN

iTrader: (11)

Did you actually measure the clearances or just eyeball it?

Paul Bell

iTrader: (9)

Is the oil pressure steady and good? I would agree with checking the flexplate.

BTLD_LS1

iTrader: (1)

I did not actually measure the bearings. I took them all with the caps to the machine shop that built the motor and the owner took a look at everything and said there was no need to replace anything besides the thrust bearing which he called the best worn out thrust bearing he'd ever seen. The only wear on the thrust bearing was primarily to the front face and said it was worn .019 under spec which is not a lot according to him.

Oil pressure is 60# at 1250 cold and rock solid, drops to 40# at 1250 once warmed up still rock solid, same as it always has been since the day it was put together. I only run Valvoline Not Street Legal high Zinc oil 10w30 + Fram Tough Guard filter.

Paul Bell

iTrader: (9)

The oil pressure looks good. Just ditch that damn Fram filter.

Does this car still have good pull & power? Any sounds if you downshift manually?

BTLD_LS1

iTrader: (1)

The car pulls amazing. Ran it out from 35-135 and it never missed a beat. Perfect downshift from 4 > 1 and upshifts 1 > 2 and 2 > 3. I did not load it up at any point, only pulls from a roll as I was on DR's and they dont hook for ****

BTLD_LS1

iTrader: (1)

Here are a few pics, It was pretty much as clean inside as the day it was put together. I was quite surprised as it has north of 350 passes on it some of which with less than ideal tuning....