Running hot on one side???

I’ve got an 86’ Sunsport with the 350 Windsor. Just rebuilt the tranny so I’m finally ready to get this rebuild on the water but now the I have 3 more issues:

1. The right side / starboard side is producing a good amount of black soot that is staining the back of the boat

2. The right side / starboard side is running much hotter than port-side. Haven’t shot it with a laser but it is very much noticeable by touch.

3. The engine will sputter out and die after a few minutes.

Once I get the bell housing and tranny back in I’m going to start working over the engine. I’m curious what steps I should take for trouble shooting? So far I have (1) tuning the carb and (2) doing a dry and wet compression check. Any other suggestions?


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The port side is running at normal temp? Impellers can dry rot pretty quickly so worth making sure you've got proper water supply and no missing impeller pieces obstructing anything.

Soot...running rich?

I just replaced the impeller and checked for any debris up to the thermostats, which was also replaced. Plenty of water is coming out of the exhaust


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Is it equal amounts of water coming out the back at idle only? Do the manifolds run cool and roughly equal with the calibrated hand on manifold check? Does it soot up and run hot as soon as you get off idle?

Is your cooling system stock from the raw water pump headed downstream as well? I just spent the last two years chasing this same issue though mine was the port side that was causing all sorts of fits.

Hey I was just browsing here and saw this thread. I have to chime in and say I chased the same issue on my boat for more than two years, I'd suggest checking out the old thread on it.

https://forum.supraboats.com/showthr...-hose-overheat

Long story short, I did EVERYTHING one could do with the cooling system front to back, other than replacing the actual RWP or circ pumps (because engine temps and overall water flow were fine). I believe my issue was caused by a partial restriction in the right side exhaust muffler which is buried under the floor under the gas tank (in my old boat, that is). As long as you didn't idle too long, it was fine - higher RPMs forced enough air and water through to keep it cool.

Just something to think about. Check out that thread if you get a chance.

Quote:

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Originally Posted by SquamInboards

Hey I was just browsing here and saw this thread. I have to chime in and say I chased the same issue on my boat for more than two....

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After rebuilding the carb it’s idling and running seemingly well, however, the temperatures of the manifolds are still significantly different and I found ANOTHER ISSUE...

The good news: I found that I’m pushing an aggressive amount of water, so I should be good there. Each side is pushing an even amount of water.

The bad news: took it out and found that it takes forever to get to max speed which is currently only 28mph. So either the engine has no power under load or I need to get a different prop, but I don’t think it’s the prop...

I removed the left hand side riser to find what appears to be an oil trial down the manifold to cylinder 7.

https://uploads.tapatalk-cdn.com/201...81d0806fdf.jpg

Are we looking at the gasket in that picture? If so, the passage on the rear should be blocked, not open (the bottom of your pic above). This somewhat forces water to go up the sides and over from the front, thus over the top, rather than taking the easy route via that rear passage. It's hard to tell from that pic, but the gasket comes with one side blocked, and it should stay that way, with the open side facing the bow of the boat. Does that all make sense?

It looks to me like the rear passage was cut out of the gasket material so it's open. See how the edges aren't straight, compared to the other openings?