www.iFourWinns.com

Picked up our new to us 2002 210 Horizon yesterday and dropped it in the lake today. Volvo Penta 5.7L motor. Runs great except for one thing. Engine temperature was pretty solid 160 - 170 initially. But after a short run at speed we dropped of to no wake speed and after about 5 minutes I noticed engine temperature climbing past 200. I increased speed slightly and the temperature started to drop. Once it got back to normal I brought the boat back up on plane(20-25mph) and the temperature was fine. Slowed down and the temp wasn't bad 175 at times at no wake speed but then it started to climb past 175. I put the shifter in neutral??? and slowly revved motor up. The temp came down.

So it seems at speed the temp is rock solid but at very low speed(basically in gear and no throttle) it starts to overheat. If I increase throttle it gets better.

I am guessing raw water pump impeller. Any thoughts appreciated????

Other question is can I replace this impeller with the boat in the water. It is the belt driven pump on the right of the motor.

Thanks.

Most likely that's the cause. As far as changing the pump with the boat in the water, the raw water hose from the transom is below the static water line, so water will come in the boat unless you put a plug in that hose and hold it up above the water line. How good is your access to the pump? If you have good access (might have to remove the rear seat to get at it, maybe not) you might be able to do this job with the boat in the water. Just make sure to get a wooden plug (the sell them at boating stores) to plug that hose. I have changed thermostats on my '88 Cobra with the boat in the water and its the same thing. I just hold the hose up, plug it, and change the 'stat.
Now once you get the impeller out, if it comes out with all the vanes, fine, but if not you should check for them in the hose from the pump to the thermo housing and inside the thermo housing itself. I'd also change the wear plate because if that is worn even a new impeller may not work as well as it should.

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Lou, how often do you recommend that impeller be changed?

Does that model raw water pump have an O-ring or other type of shaft seal that could be replaced? I have read a couple things about potential air leaks in the pump causing low speed overheating?

The previous owner gave me an new impeller in a box but it only contains the impeller and some gaskets.

Thanks

Sounds like impeller. Should change it every other season. Part of my winterization is to remove the raw water pump completely (only 2 hoses and 2 bolts), take the impeller out so it doesn't get "set" and store it all in a box in the garage. Might be a little overkill, but after having an impeller completely fail on me and being towed in, I am extra-cautious on that item.

If you end up changing it, and the impeller is "missing" some vanes, make sure to try and find them. They can get lodged in the T-Stat and cause problems.

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1996 205 Sundowner DLX
5.0FL Volvo SX Cobra
Tow Veh: 2012 Nissan Frontier Pro-4X

I'm not familiar with the Volvo impeller assembly but I'd say every other year is fine.
I look at how much water is getting exhausted under the transom mount and also engine temp as a guide to judge if the impeller is still good.

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

I'm not sure on your model pump, but mine does have an O ring and shaft seal. I believe Graham posted here awhile back that he replaced his seal and he has the same pump as you. If the seal is bad, it will leak water into your bilge while running, just start er up, and watch. If it doesn't leak, it is prob the impeller.

_________________

1996 205 Sundowner DLX
5.0FL Volvo SX Cobra
Tow Veh: 2012 Nissan Frontier Pro-4X

Removed the raw water pump yesterday. I pulled the boat and have it on the trailer in the yard. I was not brave enough to try it in the water. The impeller had taken a pretty good set so I hope that the new one will solve the overheating at idle speed issue. I will let you guys know when I put it back in the water. While attempting to clean the bilge a bit I ran into a broken bilge pump(see new post) and will replace that this weekend.

Took almost an hour of jockeying the trailer around as my driveway has a long hill and is nowhere near big enough to turn the boat around in one swing. But some blocking and jacks and moving the truck twice have it there. Remind me to take it to the marina next time and let them handle repairs. Funny I sold my other boat years ago because I spent more time working on it and cleaning it than I spent using it. So far that pattern is starting early.