Broken Piston: WHY?
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Hi Everyone
I just pulled the port motor because it was low on compression, and had massive blow by. One hole was down to 50psi. I only checked 4 of the easiest holes. Didn't bother withe the rest since the motor was coming out anyway. I have one broken piston and low compression on all cylinders.
This motor was rebuilt by a local builder about 150 hours ago. Stock 415hp 502 with a Merc 502 MPI set up in a 42 Harley that is cruised around 3500 rpm's 99% of the time. Occasional full throttle getting on plane if loaded heavy.
I think it was assembled incorrectly, but I don't know. The starboard engine has over 900 hours on it, and is getting tired, but still runs fine. So I don't think that I am abusing it. I'm sending it out to a different builder this time.
Question: What would cause this?
What questions should I be asking the new builder to ensure that it doesn't happen again?
thanks,
Steve
I just pulled the port motor because it was low on compression, and had massive blow by. One hole was down to 50psi. I only checked 4 of the easiest holes. Didn't bother withe the rest since the motor was coming out anyway. I have one broken piston and low compression on all cylinders.
This motor was rebuilt by a local builder about 150 hours ago. Stock 415hp 502 with a Merc 502 MPI set up in a 42 Harley that is cruised around 3500 rpm's 99% of the time. Occasional full throttle getting on plane if loaded heavy.
I think it was assembled incorrectly, but I don't know. The starboard engine has over 900 hours on it, and is getting tired, but still runs fine. So I don't think that I am abusing it. I'm sending it out to a different builder this time.
Question: What would cause this?
What questions should I be asking the new builder to ensure that it doesn't happen again?
thanks,
Steve
Last edited by Steve H; 07-07-2010 at 11:47 AM.