I have a 2001 mustang gt. I recently upgraded to a 5.0 stoker kit on original block. Every thing is forged and best of all parts. I put the engine back in the car and fired it up for breakin. I had the car running for 15 min total. It ran perfect untll the last 30 sec and then it started knocking on the passenger side toward the front. I shut the car down and pulle the enginne back out. I was wondering if heads can cause a knocking sound that matches the speed of the crank. I took off the belt to make sure it wasnt any accesories. I removed the engine and checked to make sure no bearings were spun and all checked out fine. Also i checked out the endplay and it was in proper range. I have not had the heads checked as that was my last resort due to the sound. Any other suggestions to check would be great.

 

Any chance the cams are out of time or tensioners aren't tight enough?

 

Was it loud or slight? Forged pistons are known to slap the cylinders until they heat up. If it was loud, hopefully your clearances were right on the bottom and the cams degreed to prevent PTV.

 

ALSO YoU MAY WANT TO CK. THE FLYWHEEL COVER . BELIVE IT OR NOT I HAD A COBRA THAT HAD A KNOCK IN IT CK EVERY THING ( IT SOUNDED LIKE A ROD WAS BAD ) AND IT WAS THE COVER SOME PEOPLE HAVE SAID IT IS A COMEN OCCURRANCE. bill

 

i am getting ready to put the engine back in..i am going to double check the timing and make sure the tensionors are at proper..and also i was wondering what is meant by the flywheel cover...is that the actuall cluch or is it a loose flywheel bolts..

 

also i got the heads back from machine shop and they found a chuck of old piston stuck in two of the ports...will tht make a knocking sound..they said head problems usually make a pinging sound and not so much of a knocking

 

Most transmissions have an inspection cover on the bottom of the bellhousing and sometimes they get hit and rub on the rotating flywheel or flexplate.

How big were the pieces? Yes, these pieces of piston can cause a noise. Trying to fix a noise over the internet is tuff because we cant hear it. You said the noise was high in the motor... correct? Do you see any marks on your new pistons and did the machine shop pull the valves out and check for damage?