Hope someone can help. I have a 455 in a jet boat which is blowing oil out of the dip stick tube. Any suggestions?

 

Check PCV to make shure its not clogged ,Are you useing a breather type oil cap?

 

What is your oil quantity and what size pan are you using?

Also, try this or other threads at that site. good stuff.
http://72.22.90.30/phpBB2/viewtopic....ht=blowing+oil

 

I check the PVC and replace it.It has a 10 qt. oil pan on it.It idles and start
great.but once you throttle down on it,thats when oil comes out of dip stick.
No smoking.

 

Would a Blown head gasket cause pressure build up in the lower end.

 

Sounds like you're getting blowby past the rings. Try a compression check to verify. Good luck.

 

When I do a compression check what I am I looking for????
Blown head gasket or Broken ring?

 

Remove all the plugs, check compression in all cylinders & write down the results. Low compression in adjacent cylinders usually indicates a blown head gasket. If readings are low overall, add a tspn of motor oil to each cylinder as you re-check the compression. An increase in compression indicates worn rings, no increase indicates worn valves.
A blown head gasket can sometimes cause oil in the radiator or water in the crankcase. Good luck.