Help! 7,4 Mercruiser hot exhaust and riser

[Lespaulguy]

I just bought a Baja 232 performance with 7,4 merc.
Was running this weekend, and all of a sudden I started smelling burn. Stopped and noticed that the rubber boot or flange connecting the exhaust to the stern was smoking, but this only on the Starboard side. Riser seems fine on the port side, I can put my hand on it. Engine temperature seemed fine at around 165?

What is going on here? Am I dealing with anything major?

 

[Bt Doctur]

Re: Help! 7,4 Mercruiser hot exhaust and riser

clogged manifold or riser most likely

 

[Lespaulguy]

Re: Help! 7,4 Mercruiser hot exhaust and riser

What does that mean? Is it a matter of taking apart and cleaning, or they are ruined and purchase new?

 

[Bt Doctur]

Re: Help! 7,4 Mercruiser hot exhaust and riser

something shut off the water flow to melt the rubber exaust coupler. rust, scale and sand .how old are they? 5-6 years and your due for replacement.

 

[HT32BSX115]

Re: Help! 7,4 Mercruiser hot exhaust and riser

What does that mean? Is it a matter of taking apart and cleaning, or they are ruined and purchase new?

It's really not recommended to "clean" risers or manifolds. They're designed to rust internally and slough off oxidized metal internally up to the point of clogging. That is when you replace them (both sides)

If you "clean" them like some have successfully done........ you get into an area where you really don't want to be. The internal walls get can get thin enough to leak (salt or fresh) water back into the exhaust area and then into open exhaust valves once the engine has stopped running (you always have open or opening exhaust valves when the engine stops)

If the water is allowed to sit on top of your piston(s), like while you're on the way at home thinking about going back to your boat next week or after "winterization" and THEN, ALL winter............ the engine is slowly being ruined and you find out about it the next time you try to use your boat.

So, most of us would suggest replacing them as a "kit". (exhaust "Kits" are available here on iBoats and MANY other marine parts places)



Cheers,


Rick