2008 ski nautique starboard side bank overheating

[BenjaminHambling]

So, been running our 2008 ski nautique with an excalibur 343 (raw water cooled) for most of the summer with no issue. However this week whilst running the engine overheated, the starboard side bank exhaust started to melt both the rubber and the fiberglass. After allowing it to cool overnight I made the usual checks, sea strainer, impeller, thermostat. All we fine. When starting the boat i realised that the fiber glass exhaust had been ruined, with water pouring out of it. This was replaced.

Now, simply running the boat in idle, the starboard side bank becomes extremely hot however the port side remains cool.

What could this be happening and how can I fix it

Any advice/help would be great

[wakejunky]

I recently had a very similar problem but, it was old impellor parts from a previous blown impellor. I ran for over a year without any problems and then had the same problem you have, one side hot, one side cool. Found that a couple impellor parts had finally work their way to the thermostat housing and prevented water from going to one of the exhaust risers. Pulled the thermostat housing to find them right there.
In your case, I would start with pulling the the hoses off the exhaust risers, run the engine and find out what water is flowing to the exhaust risers. Then you know whether it's something obstructing from the block or something in the riser.

Chris

[xrichard]

The flow of water goes from the raw water pump to what PCM calls the "lower fill riser". At the lower fill riser, the water can flow freely to the "upper fill riser" and also to the recirculating pump. The upper fill riser is just a "T" that branches off to each exhaust manifold. When the thermostat is open, water flowing through the block dumps into the upper fill riser out out to the exhaust manifolds. When the thermostat is closed, the thermostat, recirculating pump, and flow through the block are not in the path of water cooling the exhaust.

The good news: if one exhaust manifold is getting cooling water and the other isn't, there aren't that many things to check. Open up the upper fill riser and look for anything blocking flow; pull off the hose from the fill riser to the exhaust manifold and check for obstructions; check for obstructions where the hose attaches to the exhaust manifold. If there is nothing found, then there's likely an obstruction inside the exhaust manifold or exhaust elbow.

Another possibility: you're not getting enough water through the motor and, for whatever reason, the water getting through is flowing more to one side than the other. If this is the issue, then you should double check your impeller and also look for any leaks in path for the raw water intake. Nautiques have a strainer between the raw water pump and the thru-hull fitting...and it often is a problem. Just a slight leak at the strainer will cause the engine to over heat. Check the strainer bowl for cracks, check the gasket, look for any drips coming from the strainer.

[BenjaminHambling]

Thanks for the advice guys, I'll follow it and let you know how it goes.

Ben

[BenjaminHambling]

Well removed the exhaust elbow assembly, the gasket was fried. Then all became clear, everything is clogged with carbon, and i mean clogged. I'll post some pictures on here for future reference should anyone have this problem in the future.

Got two new exhaust manifolds and exhaust elbows on order. Cheers for all the help.