Exhaust manifold temperature

[prc03sx195]

I have an 03 4.3L V6 mercruiser I/O and yesterday out on the water I was checking the engine over and felt the tops of each manifold and the right side was cool to the touch and the left side was much hotter. Is this normal? Im curious because I was caught up in some seaweed and until I got it removed it wasn't running good. I just don't remember the manifolds being different temps like that. Thanks

paul

 

[tpenfield]

You may feel about a 10 degree difference. You would need an IR temperature gun to check the exact temperatures.

 

[prc03sx195]

I am feeling more than a 10 deg difference, right side I can hold my hand on and is probabl;y 100-110 and the other I cannot hold my hand on at all. Thanks
paul

 

[harringtondav]

Couple thoughts. At idle - 1000 rpm on muffs I notice a difference in the exhaust water outflow at the transom plate's two exhaust ports. I've also noticed a 'feel' difference between the exhaust risers while on muffs.

Your raw/sea water line feeds the thermo. hsg. from the left, splits to the exhaust manifolds, plus provides cold water to the thermostat. The path to the right exhaust manifold hose is more direct than the 180 degree turn back to the left manifold. So the right side may get more cooling at low engine rpm.

Next time on the water, with normal temp. gage, Idle at 1000-1200, and see if the two exhaust risers match in feel. Your impeller seems to be pumping enough to cool one side and your engine (you didn't mention a temp gage overheat condition).

I can't imagine seaweed making it's way thru the intake slots, passing thru the impeller, and fouling just one of three critical use points. But weird stuff happens.

 

[porscheguy]

At idle I wouldn’t worry too much. I’ve got the same engine and when running on the garden hose it sometimes does the same thing. One manifold will feel just warm, and the other will be almost too hot to touch. Come back 2 minutes later and temps on both have about equalized. I pay it no mind. I’d be more concerned if it were happening at cruising speed.

 

[Oshkosh1]

At idle I wouldn’t worry too much. I’ve got the same engine and when running on the garden hose it sometimes does the same thing. One manifold will feel just warm, and the other will be almost too hot to touch. Come back 2 minutes later and temps on both have about equalized. I pay it no mind. I’d be more concerned if it were happening at cruising speed.

x2...I see/feel a noticable difference when running on the hose but once it's in the water...they're both relatively equal. Equal enough I haven't bothered to "hit" it with my IRT.

 

[wahlejim]

How long were you caught in the weeds and what did you do to try and get rid of them? I have seen beople gete caught and try to rev out of them without kicking the boat in reverse to blow weeds off the intake grates. Engine overheated due to lack of water flow. If that happened, you may have damaged an exhaust shutter, restricting flow on one side while the other sides flowing as it should. An IR check is your next step, or examine your shutters. You are probably ok, but checking the temperature will give you piece of mind.