5.7 engine overheating

[nautiques_199]

I am at a loss with my boat. It is a 2003 ski 206 with the 5.7/older style v-belt setup. I got the boat out from winter storage this weekend and got it ready. I changed the water pump impeller, but other than that I just put the plugs back in the block and fired it up. Boat fired right up as usual but it is overheating now. I checked to make sure impeller was pulling water in and it is. Checked the intake screen and that is clear. The boat will only overheat when in the lake. If it is running on a garden hose it runs normal. Anyone have any ideas where to go from here? Dealer is 2 hours away so I'd really like to save a trip. Thank you


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[Nautiquehunter]

I would start by looking at the impeller. If its not a PCM brand impeller . Some of the off brands will shread almost immediately.

[Fgroce]

I second the impeller, make sure it is a sherwood. When you removed the old impeller was it shredded. If so you may have rubber up around the thermostat. I found rubber plugged in the holes for the exhaust manifolds. When the boat was in the water did you see any bubbles in the strainer, if so you have a air leak. Also make sure you have the hoses tight going to the water pump, hope this helps.

[nautiques_199]

I only changed the impeller for routine maintenance. There was nothing wrong with the old impeller. I bought this impeller from Amazon https://www.amazon.com/gp/aw/d/B01BE...?ie=UTF8&psc=1
I checked all connections for leaks and there isn't any. No bubbles in strainer either. I will get a genuine Sherwood impeller ordered and try that. Thanks for the help

[Tom_H]

I don't remember off the top of my head, but can the water pump on that engine be installed backwards like the old Ford blocks? That would certainly cause the problems you're seeing.

[Quinner]

There is a top on that pump, be sure it is installed correctly with the word TOP on top. Heard of problems with generic impellers, I would put your old impeller back in, if problem goes away you know it was the impeller.

[Nautiquehunter]

Check the impeller again Amazon is not a good place to buy parts . Its cheaper at Nautiqueparts and its genuine PCM.

[nautiques_199]

I put the old impeller back in and problem went away. Lesson learned the hard way unfortunately. Thanks everyone for the help.

[Nautique Fan]

Don't forget the Planet Nautique discount when ordering parts from Nautique Parts. NPD gets you 10% off.