NEED INPUT ON LEAKING FRONT OIL SEAL 572 OHIO CRANK ENG
05-13-2007, 06:02 AM
#11
Senior Member
MASTER BUILDER
Join Date: Jul 2006
Posts: 184
It could be excessive blowby too. When you describe it happening at a certain rpm and above, there could be excessive crank case pressure being built up, causing it to push oil out the fron seal. Just a thought. That could be from either in adequate breathers, or, a bad cylinder job.
I am just about done with a SBC 383, from a marine application, that was basicaly doing the same thing, except it would push the dipstick out, and leak oil there. Hit about 3800 and, out it cam. No matter what the guy did. Unfortunately, he bought this engine from a similiar source, that, should really just stick to selling parts. After disasembling the engine and doing some measuring, found the piston to bore clearance, to be about .004 bigger, that the max recomended clearance for the piston type in the engine. Speed-Pro coated hypereutectics. The call for .0015-.002 max. For a marine deal, you set them at .002, maybe even .0025, because of the cold water, always in the block, so, the piston grows a bit because its subjected to combustion heat, and, its aluminumn, but, the block never growns, because it stays cooler, than it would say in a car, so, you need to set the bore clearances a bit more. Well, anyhow, these were at .0055 on the piston to wall. Thats basicaly .004 to much. Causing excessive blow-by, and the problem. They also found it necessary, to open the guide clearances in the NEW Dart iron Eagle heads, to .0035. So, not only am I totaly re-doing the engine, i had to put new guides in new heads. YOu could have something similiar going on. Would suprise me
Frank
I am just about done with a SBC 383, from a marine application, that was basicaly doing the same thing, except it would push the dipstick out, and leak oil there. Hit about 3800 and, out it cam. No matter what the guy did. Unfortunately, he bought this engine from a similiar source, that, should really just stick to selling parts. After disasembling the engine and doing some measuring, found the piston to bore clearance, to be about .004 bigger, that the max recomended clearance for the piston type in the engine. Speed-Pro coated hypereutectics. The call for .0015-.002 max. For a marine deal, you set them at .002, maybe even .0025, because of the cold water, always in the block, so, the piston grows a bit because its subjected to combustion heat, and, its aluminumn, but, the block never growns, because it stays cooler, than it would say in a car, so, you need to set the bore clearances a bit more. Well, anyhow, these were at .0055 on the piston to wall. Thats basicaly .004 to much. Causing excessive blow-by, and the problem. They also found it necessary, to open the guide clearances in the NEW Dart iron Eagle heads, to .0035. So, not only am I totaly re-doing the engine, i had to put new guides in new heads. YOu could have something similiar going on. Would suprise me
Frank
