Re: 115merc( L-6)EXHAUST/MILKY MESS?
The following is a process that was written by Jeff G. It may help you with your water/exhaust issue:
Repost: Water Ingestion & How To Fix It.
I have been asked how to do this so for all here goes.
One of the major complaints of the post 73 inlines was the leaking side plate and water ingestion. The side plate has always been made out to be the culprit but in most cases it isn't so!
There are 3 common ways water gets into the motor. The inner side plate, the baffle plate, (the middle plate on the side of the block) and the lower seals.
Probably the most overlooked and most common is the lower seals. To replace them the block does not have to come apart. The lower end cap can be removed with a simple puller. Replace the seals using some perfect seal around the outside case of the seals and pack grease
between the seals. They must have both lips facing down! Very important.
If the end of the crank is buggered or rusty a speedy sleeve can be installed. The actual location of the seals can be changed to avoid any small grooves in the speedy sleeve.
The inner side plate is pretty straight forward. If the plate is old replace it. If there is a lot of carbon and no sign of water, LEAVE IT ALONE!. If the plate is relatively new and is leaking it can be straightened and reused. You can gently straighten it on the edge of a soft wood table. I recommend replacement in all cases.
Always use a new Mercury gasket, not aftermarket. Clean and retap all the bolt holes, clean the bolts with a wire wheel on a grinder. Then clean the bolts with carb or brake cleaner. Do the same with the bolt holes. Hand clean the gasket surfaces on the block and plate with a
razor blade held at right angles slowly scraping the surface. Wipe clean.
Run a small bead of red high temp RTV sealer on the block. Do not use any RTV with copper. Lightly smear the sealer to ensure complete coverage and a thin coating, don't use too much. Put the gasket into place and do the same with the gasket, so it is coated now on both sides with RTV. Place the side plate into position. You will notice a couple bolt holes are elongated and tight. These are used to line up the plate. Use a drop of red loctite (permanent) on each bolt and finger tighten
them. Once all are installed you can torque the bolts in three even stages to 200 INCH pounds. Start in the middle and work outward in clockwise circles. Once torqued leave it for at least 24 hours. Do not re-check torque!
The third area to check is the baffle plate. this is the middle of the 3 plates on the exhaust side of the motor. Please read the following very carefully. This plate is quite often the cause of internal leaks!!! Yet it is never checked, nor is it mentioned in any service manual!
The baffle plate has some zig zag ridges that meet with the corresponding ridges on the inner plate. These ridges seal and baffle the exhaust for tuning purposes. With the block on it's side and the inner plate torqued, lay the baffle plate on the block WITHOUT a gasket.
Holding it down in the middle see if it rocks from side to side. If it does it will leak. Next while holding it down with finger pressure look into the cavity from the bottom of the block. If you see any light around the edges, it will leak. If checked with a gasket the thickness of the gasket may hide the high centering of the plate.
You will need to true the baffle plate. Do not try to true the inner plate. You can use a large table sander or a file, or any machine shop. True the ridges of the baffle plate until the plate no longer rocks and very little or no light is visible around the edges. You may not be able
to get it to the point of no light. Place a very small smear of grease on the inner plate ridges and place the baffle plate on the block. Remove the baffle plate and check for the transfer of grease. Keep filing the baffle until no grease is transferred. What you are doing is preventing the baffle plate from high centering on the inner plate.
Once the plate is done you can assemble the motor. After dropping in the pistons and checking the rings, place the baffle plate and exhaust cover (outer plate) on the block using some RTV as a gasket sealer. (You can run a very thin bead of red RTV on the baffle ridges as well, although not necessary for pleasure boating) A very thin coating will do. Black or red is acceptable. Torque the bolts to between 150 and 200 inch pounds in three stages beginning in the middle and working outward. Use some blue removable loctite on the bolts. Clean the bolts and holes as you did the inner plate.
This should cure your water ingestion problems.
