Spun Rod Bearings

Discussion in 'SVT Tech Forum' started by 99Cobrakv, Jan 7, 2006.

  1. I have a 99 cobra. I have recently rebuilt the motor, Twice, and both times I have spun the rod bearings. I built the first motor myself and use plenty of grease on the rod bearings. The second time the motor was built my Mcallister Brothers Racing and it too spun a rod bearing. I believe all the clearences were within spec for an aluminum motor. Has anyone had this problem and if so what can be done to prevent another spun rod bearing.
  2. What exactly were you and the car doing when you spun the bearing? Were conditions similar both times the bearings let go? Curious...

  3. checking the oil level and making sure you don't go low
    not revving the hell out of it
    don't baby the car for awhile and then start beating in it
  4. Reply

    The first time I just got done installing a set of Probe pistons and Manley H-beams. I used a lot of the bearing grease. Had the mechanices install the engine back in and they started it. Upon recieving the car I started it and heard a rattle. Asked what is was and they didn't know. Over time it got worse and worse. Finally stripped the motor down and found that it was a spun rod bearing. Second time, still not sure what it was I had mcallisters build me a motor. 03 cobra cams, probe pistons, H-beams, DSS retainment system, Got and intercooler and blower. Had shop install the motor......upon recieving the car I started it and I can hear same rattling sound that was present when rod bearing was spun. I don't know what is going on. Oil pressure at idle is at 40psi and 75 under load.
  5. Wow! So the damage happened within the first few hours or minutes of the engines life huh? Sounds to me like there was inadequate lubrication on initial start up. I know you stated you lubed the snot out of them with assembly grease...

    I'm thinking you may want to use an electric primer to pressurize the oiling system before turning it over for the first time. :shrug:

  6. did you clean off the crank surfaces before reassembly? are the new pistons/rods balanced out to work with the crank? i heard there's a certain weight that has to be used