Leaking Exhaust Gasket

[DWNewt]

I recently rebuilt and successfully broke in the engine with no problems. For the 3rd time I'm having to replace the outside exhaust gasket on a 77, 75hp Evinrude. It runs great until the gasket leaks, (like a high pressure stream). After it starts to leak, the engine sounds like it's sneezing. There does not appear to be any water in any cylinder. This time I'll apply more sealer to the manifold on install. When leaking, does this affect compression causing the engine to run eratically? Is there an underlying problem, or do I just need more gasket sealer as suspected? One other thing, is there a way to replace this without removing the powerhead from the engine?<br /><br />Thanks

 

[OBJ]

Re: Leaking Exhaust Gasket

Once thing for sure Tech Man, make sure the surfaces are CLEAN. I find it helps to torque all the fastening bolts. This ensures an even pressure all around the cover.<br /><br />The leak on the outside gasket should not effect compression. What it's probably doing is spraying over onto the spark plugs causing them to more or less short out and giving you a miss.<br /><br />I've never change one with the block still attached to the midsection but I would guess the bottom fastening bolts will be a little hard to get to. Also check the gasket surfaces are flat and don't have any warpage. You can do this with a known straight edge.

 

[DWNewt]

Re: Leaking Exhaust Gasket

Thanks, I have a manual and torqued all according to the book. I did not see and perhaps overlooked what I'm asking, but to what pressure should I torque the exhaust bolts? Really seems to be the problem.

 

[emdsapmgr]

Re: Leaking Exhaust Gasket

When you have the exh cover off, check to make sure there is no porosity (small casting holes) in the actual inner casting. At planing speeds, the engine water pressure can also cause leaks like you mention.

 

[DWNewt]

Re: Leaking Exhaust Gasket

will do

 

[OBJ]

Re: Leaking Exhaust Gasket

Torque the bolts 7 > 8 ft lbs. Maybe try a two stage torque....start across the middle and work your way out at say 5lb and then do the same at 8lb.

 

[DHPMARINE]

Re: Leaking Exhaust Gasket

Are you retorqueing the bolts after warming the engine.They always loosen up for me.Long bolts,many gaskets and covers.<br /><br />While you cannot get a torque wrench at all the bolts,you can get a feel for tightness with a regular box wrench.<br /><br />Also Permatex type 2 is a little (lot) thicker and helps with some warpage.<br /><br />DHP

 

[DWNewt]

Re: Leaking Exhaust Gasket

Thanks DHPMARINE, installed with Permatex type 2, working great. They do loosen up after running the engine. Will lock washers help with this?