rncotton

Well gang, you know I don't usually show up unless I'm having a problem. Short history: 2001 WS6, cracked ring land on piston in 2009. Shop took about a year, rebuilt the motor twice, still had problems, they cracked my block and destroyed everything, went out of business, and finally got a fresh block and enough pieces to get a motor back in my car and it ran fine for 5 months.

Last week I was driving home on the interstate and it started making a God-awful knocking and sounded like the motor was about to fly apart. I let off the gas, RPM went down, noise went down with RPM. It's definitely rotational. Looked in the mirror and didn't see smoke, checked my oil pressure and it's holding, so since I was only 2 miles from home I said "Screw it ... it scatters or it gets me home." Got home and looked under the car. No oil puddle, no rod sticking out of the block.

Over the next few days we have: Checked oil / coolant for cross-contamination and metal. Dropped the transmission and bell housing to inspect clutch, pressure plate, flywheel, etc, hoping to find something broken and flying around the bell housing. We fired it up without the tranny and the noise was still there, verifying it is in the motor. We replaced the harmonic balancer last night. Still there.

Is there anything else I should be looking at before I decide to yank the motor out and tear it down?

The noise is a significant knock with the occasional metal-on-metal scraping sound. It increases with RPM, definite rotational. When it happened, I didn't feel a sudden loss of power and didn't seem like it was suddenly running on 7 cylinders. I'm wanting to check everything I can before making the commitment of pulling the motor.

Thanks guys .... and if I do have to pull it, where's the best place to get a short block? I don't need anything fancy and forged as I'm just running 243 heads and the Comp HR265 cam w/ beefier springs. This motor won't be seeing more than 400 HP.

pozesd99'

iTrader: (3)

junk yard for a lq9 block :-)
and it sounds like the block but you can always check the pushrods..

parks450

iTrader: (17)

AGREED on the 6.0 as he said check the pushrods to make sure one isnt bent. Could have came off a rocker or may have not been fully on in the first place. Do a compression check on all 8 cylinders make sure they have good compression and hold it.

rncotton

Pulled the rockers and pushrods on both banks ... all look pretty.

I'm trying to go through a logical process of everything I can remove / check in-car before pulling the motor. So I guess my next move is to remove the heads so I can see the valves, top of the pistons, and the lifters?