JTonJuice

hey guys i bought a motor off cl for my pops truck. the guy claimed it was rebuilt with 30,000 miles on it so i bit and after swaping it in theres this knocking sound. i primed the motor for a good five minutes prior to firing it.. what do you guys think of this sound..
http://youtu.be/5435RxygD9g

sechott

I don't think it is a rod, maybe piston slap or something on the top end.

combatcarl

If you can hear it at idle, and your plug wires are good, pull them one at a time, when it gets quiet, there's your problem cylinder. If it doesn't go away completely, its probably a piston issue. Sounds to me like a bad wristpin. Lots o' slapping going on there. Any metal shavings in the oil?

JTonJuice

thanks for the reply guys i had to time to drop the driff and oil pan it spun the bearings. i think they ran it with out oil. i will try to just replace the bearings tomorrow and see the crank is a lil scratched up..

abecedarian

Don't put new bearings in without having the crank journals turned. It'll cause more problems sooner than later.

JTonJuice

how long do you think ill last if i just put new bearings in without machining the crank? i dont really wanna take the whole motor apart aagain and he needs it for work asap.

abecedarian

Honestly? I won't give an estimate.
The best you could do is try to plastigage the crank where it's least worn, for each journal and buy the appropriate bearing for each journal.

Or source a used engine and install that for use while you fix this one.

JTonJuice

i replaced just the bearings its been running good so far about 200miles on it..