Risers....one hot....one not....

[Manipulator]

The other day I stopped into a cove and lifted the engine cover to let the heat escape. I put my hand on the exhaust manifold riser and noticed that it was hot to touch. Not extremely hot, but hot. I then put my hand on the other riser for comparison and it was warm but not hot to touch. I then moved to the exhaust manifolds and both were warm to the touch. The elbow in question had been replaced about 50 hours ago. It is after market and a little different looking than the original but the bottom was the same (where it attaches to the manifold). What could cause this? The exhaust manifolds were replaced at around 400 hrs and the boat has 755 hours on it. I checked both manifolds when I put the new riser on and both were clean and free of debris.

 

[crazy charlie]

Re: Risers....one hot....one not....

Did you use any type of sealant on the mating surfaces???? Excess sealant will clog the passage ways.Thats why most makers of risers and manifolds say only to use the gasket .No sealant.Charlie

 

[rbezdon]

Re: Risers....one hot....one not....

It also couyld be the wrong gasket. Has the riser been too hot the whole 50 hours it has been installed?? If not, then obviously there must be some "junk" clogging the riser.

 

[Bondo]

Re: Risers....one hot....one not....

Let Me Guess,...........<br /><br />It's the Starboard Riser,....???..... Right,.??<br /><br />Is it a SBC,.?? the starboard side Always runs Noticeably Warmer,......<br /><br />No,........ I Don't Know Why,.......

 

[Manipulator]

Re: Risers....one hot....one not....

Well I remember the guy telling me at the marine shop "no sealer". But when I took the riser off it had sealer. So I bought sealer and covered both sides. My shop manual said to use sealer so I did, but I only used a very thin layer. The gasket came in a set of two so I changed the other side as well. I also used sealer but that side really doesn't get hot.

 

[DHPMARINE]

Re: Risers....one hot....one not....

I know you are trying to look out for problems arising.Keep an eye on your temp gauge,and if you DO run, hot hands on feeling can help you out.<br /><br />But the fact is parts of the engine do run warm and some warmer,and some hotter.Now that you have done this you have a reference point to deal with.<br /><br />When you have a problem you can better diagnos it now.<br /><br />DHP