The first time getting my current boat wet, I had a similar problem.  There is a spade that is part of the front oil pan gasket set that pushes through the timing cover to retain that part of the of the oil pan.  The previous owner removed the timing cover without removing the pan and used blue RTV to seal it back up.  One of the holes (one on each side) on the timing cover didn’t get filled with RTV and at the first application of throttle, it became an oil geyser that hosed down the entire starboard side.

Point being, it could be something small.

I would throw in a set of K&N push-in breathers and try it again.  Be advised, these will make a mess also.



Engines are remarkably robust yet surprisingly fragile.  Look at it his way, you are learning a lot.

What rear main seal should I get?  I see 1 piece and 2 piece seals. Marine or regular. Not really sure what exact year my motor is. http://www.summitracing.com/search?SortBy=BestKeywordMatch&SortOrder=Ascending&keyword=454%20rear%20main%20seal

Mk4 will be a 2-piece

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Mk4? do the serial number on pic mean it's a mk4?

If you do a Google search for "big block Chevy casting numbers (and your number)" you will find many reference charts.  If you post your number, I can look it up for you in my parts interchange book if you have difficulty finding what you need.  I was just making a statement based off of the shape of the water passages.  The gen5 and gen6 are a different shape.

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Yeah I did Google and bunch different came up. Different 454's  some said even 427's. If you can look it up I'd appreciate it

http://www.mortec.com/bbc.htm

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If 3963512, 69 427 & 70-76 454 2 & 4 bolt mains.  I will verify in my book when I get home.

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If 3963512, 69 427 & 70-76 454 2 & 4 bolt mains.

4.250 bore, 9.8 deck height

Mark IV

Recommend any special type rear main seal?

I wouldn't go cheap.

I really like the 1-piece oil pan gaskets.  I think mine is from SCE.

Put a little dab of silicon in the corners where the gasket transitions from flat around the rear cap and timing cover to help prevent leaks.

I like to slightly misalign the rear main seal relative to the block/cap and put a little dab of silicon where the seal halves meet.

Double check everything.  Be patient and meticulous.

I wouldn't go cheap.

I really like the 1-piece oil pan gaskets.  I think mine is from SCE.

Put a little dab of silicon in the corners where the gasket transitions from flat around the rear cap and timing cover to help prevent leaks.

I like to slightly misalign the rear main seal relative to the block/cap and put a little dab of silicon where the seal halves meet.

Double check everything.  Be patient and meticulous.

Sce? Okay silicone seems to be key factor on a lot of gaskets. Will do.

Before I do any of that I would try just changing the breathers after cleaning with citrus cleaner.

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Cleaning?  And yeah that's exactly what my uncle told me (he's a good mechanic) but I think I might as well do it now and not worry about doing it later.  Plus I had a mysterious leak back there last time out too. And I'm thinking it was rear main because I was getting oil shooting up from the flywheel spining. Like how it's doing now but very little.. and