Exhaust Manifold Temps Uneven - DON S - I would like your thoughts PLEASE!! Thanks!

[pete636ua]

1999 Mercruiser 5.0L A1/G2

Started and warmed up starboard engine to operating temp in the water noted one exhaust manifold and riser warm to the touch and the other was noticably cooler. Is the normal? Been having intermittent cooling problems on this engine. Impeller changed prior to this season. Has had T-stat changed 2x recently.

The Port engine same sequence as above both manifolds&riser are cool.

Planning on removing the warmer riser to have a look for restriction....is this the way to go??? is there any other advice??

Thanks
Pete

 

[Robert.E]

Re: Exhaust Manifold Temps Uneven - MERC 5.0L

Re: Exhaust Manifold Temps Uneven - MERC 5.0L

I have the same problem on my Merc 5.0.
I have removed the Exhaust manifold and i have been trying to cleant it.
I am about to order a new set of gasket and reinstall it.
I will let you know if it helped when im done.

/ R

 

[andy1canada]

Re: Exhaust Manifold Temps Uneven - MERC 5.0L

Re: Exhaust Manifold Temps Uneven - MERC 5.0L

Howdy Pete!

I'm breaking in a new 4.3/Merc and while out for a short run with my mechanic he told me that it's typical for one manifold to run a little hotter than the other; something to do with water taking the path of least resistance. Regardless, he says if all is well, after a few minutes when the engine is up to operating temperature you should be able to hold your hand (indefinately) atop either riser without getting burned.

I'm sure one of the other boys could offer additional advise (correction) on this subject.

Hope this helps.
Cheers,
Terry

 

[pete636ua]

Re: Exhaust Manifold Temps Uneven - MERC 5.0L

Re: Exhaust Manifold Temps Uneven - MERC 5.0L

Howdy Pete!

I'm breaking in a new 4.3/Merc and while out for a short run with my mechanic he told me that it's typical for one manifold to run a little hotter than the other; something to do with water taking the path of least resistance. Regardless, he says if all is well, after a few minutes when the engine is up to operating temperature you should be able to hold your hand (indefinately) atop either riser without getting burned.

I'm sure one of the other boys could offer additional advise (correction) on this subject.

Hope this helps.
Cheers,
Terry

Well...I am just goin on that the other engine is not like this one...Both manifolds/risers on it are cool. The problem engine has one that is warmer than the other - I'm thinking path of least resistance could also be a restriction??

Thanks
Pete

 

[Don S]

Re: Exhaust Manifold Temps Uneven - MERC 5.0L

Re: Exhaust Manifold Temps Uneven - MERC 5.0L

Next time you start it up to warm it up and the one side gets warmer, run the throttle up to 1200 to 1500 rpm and see if the temps equalize. If they do, it probably normal, if not, pull the riser and inspect it.

 

[pete636ua]

Re: Exhaust Manifold Temps Uneven - DON S - I would like your thoughts PLEASE!! Than

I have removed the riser and found it and the manifold clean as a whistle. HOWEVER---I found one half of the exhaust shudder flipped up causing a restriction and the other piece is missing.....how critical is it to get that piece out??? I have tried for a bit with mechanical finger and no luck....any opinions? advice???

Thanks
Pete

 

[Don S]

Re: Exhaust Manifold Temps Uneven - DON S - I would like your thoughts PLEASE!! Than

Bondo, Picture please......
Pull the drive, find the shutter parts, and make sure everything is clear. (Pull the prop and look also) then put in new shutters and riser gaskets (Both sides) and see what happens. Don't just try to troubleshoot around a know problem.