340 engine overheating

[kbbb73]

I am having a problem with my starboard engine, I start it up and the alarm sounds at about 120 degrees, when I turn it off and check the engine the right exhaust manifold is very hot and the left one is cool. any ideas as to why this would happen...before I call the mechanic to have a look at it?

 

[fropleyquark]

I am having a problem with my starboard engine, I start it up and the alarm sounds at about 120 degrees, when I turn it off and check the engine the right exhaust manifold is very hot and the left one is cool. any ideas as to why this would happen...before I call the mechanic to have a look at it?

First thing I would check is your water pump impeller. Do a search and you should find lots of info.

 

[kbbb73]

thanks, the water seems to be pumping, it's just one side thats hot? I'm thinking something must be plugged?

 

[Hampton]

True that, but on a much more serious note, you may very well have a corroded exhaust manifold, or 4. Are they original? They are aluminum and normally fail soon after the 3rd year or so, depending on use, salinity, rinsing... I honestly don't know the symptoms of a corroded manifold, but I imagine metal flaking off and blocking water flow could be one of them. Feel around the bottom edges of your manifolds when cool. Corrosion and flaking would be signs.

Read this: http://clubsearay.com/forum/showthread.php?t=6038&highlight=manifolds

 

[Jimmy Buoy]

I learned this the hard way!

Make sure you check your cooling lines to your prop shaft seals. If they are fed by the same exhaust manifold that is being starved of sea water, the shaft seals will overheat and fail or melt in my case. Expensive! :smt013:smt013:smt013

Also, check your exhaust hoses that attach to the stainless steel risers. Even though they seem ok on the outside they may be burned on the inside and collapse. Mine actually had two holes burned right through the one exhaust hose on the port engine. The other engine had no signs of burning on the outside but the inside revealed a separation of the two layers of rubber with the inside layer bulging down and becoming brittle on the right side.:wow:

Both engines seemed to be running well. Water flowed out of the thru-hulls fine and the temps were 160 for both engines. All four manifold/risers were quite plugged with 'sea creatures" and/or corrosion.:smt009

Replaced all 4 including the water rails (your's may not have the water rails). Lots of crap in all four exhaust systems!!:thumbsup:

 

[kbbb73]

thanks guys!

 

[83searay]

Check the heat riser, if the riser is HOT replace it, I had the same issue on my SD260 on port side trying to figure it out was a pain in the ass, hope all works out for you.