Engine Break In

[jbarraclough]

I have twin 350's in an older cruiser. I had lots of blow-by in one motor which we tried to fix for years to no avail. Decided to rebuild and found that the bore was slightly too big for the pistons, so all were leaking just enough to cause back pressure while still showing acceptable values on compression and leak down tests. What a joke!<br /><br />Anyhow, I had the engine rebuilt and I am seeing lots of blow-by still. I burned through a quart of oil in the first 2-3 hours of break in. The guy who rebuilt it assures me that this will continue to happen throughout the first 10 hours or so until the rings seat. I trust the guy who did it but I'm looking for a second opinion. I've never heard of losing that much oil during break in and I've had to break in several motors in the past. Can anyone help?

 

[Big-E]

Re: Engine Break In

well i can tell you right now i have 13 hours on my 3.0 mercruiser that i just rebuilt and it has used 1/2 qt of oil. I rebuilt the motor myself and am sure i didnt scratch anything. The machine shop that did the machinging said it would be several hours till she dosnt burn anyoil. I can tell you it seemed my motor had alot of blowby in the 1st hour it was alive. After that it stopped smoking like a frieght train and has seemed to only give some blowby when i jump her on plane and thats about it. I would watch it but if your over 10 hrs and still using a qt every 2-3 hours i would take it back.. <br /><br />Unless im wrong, <br /><br />later, <br /><br />Big-E