wwwTOPDJcom

40-70mph temp is 150-160 502gsi volvo version of a HP500 but its only 425hp, if I try to idle or go slow it gets hot
put a new T stat in a new impeller. I also blew the coolers and drained the block on both side.

their is a slight chance I ruined the new impeller when testing
after replacing the parts,

seems like 3000rpm is the sweet spot any slower and the temp climbs

jeff32

easy to burn I'd re check the impeller...

wwwTOPDJcom

well its not rust, freshwater engine with 108hrs, the old impeller looked good to my eye. I hope thats what I did.
The one I removed I couldnt run slow or fast with it would overheat either way.
But I removed the T stat to get it home 2 weeks ago and also could not run it under 30-40

fireboatpilot

Might not be just the impeller but it might need a pump housing as well if its plastic. Once they get scored their junk.

Boat Tech

What year, And what drive do you have? You might want to try as a test, Installing some clear hoses right before the water goes into the impeller housing and look for a lot of air bubbles while running it, If you do have bubbles, Then you are sucking in air some where from there back to the drive. If it does not have bubbles then you might have a bad impeller or housing In a few spots on the housing, or the water flow system is blocked some place, Or you might even have a bad water circulating pump. Good luck with it.

wwwTOPDJcom

crank driven water pump solid brass, it was clean no scoring
its a breeze to work on that. I did blow all the lines out remove both block drains and no signs of rust at all. How does the circulatory pump fail? I have another pump impeller so I will try that first.

question should I see bubbles in the sea strainer?
I did test this on my hose which is 30 degrees cooler than the lake
and worked fine before we went yesterday.

What really sucked is I went 35 miles up the lake at about 65mph in smooth conditions no overheat,, but later in the day conditons were bad and I was forced to run 40-45 in 3 footers not a whole lot of fun with the wife and kid onboard. I had no choice anything under 40 and it started getting hot.

Audiofn

You obviously need a bigger boat.

No you should not have air in the sea strainer. You will ussually have a little bit but no bubbles. This is with the boat in the water not on a hose.

wwwTOPDJcom

love the big boat idea but then I need a new truck too

dookie

I know this may not be your case , but i wanted to post my experience anyway.
We bought our boat a month ago , and it was my first circulating water pump experience , (i had always owned alphas) . While on the test ride , i noticed the sellers wife mentioned more than once the troubles the they had with changing pumps all the time and overheating troubles. So before i ever took the boat out , i changed both pumps out with new ones , just to be safe.
On pretty much our maiden voyage we backed the boat onto a sandbar and tied up with friends . At the end of the day upon departure i noticed i filled all hoses completely full of sand. And both motors were pretty much not cooling , got towed in.
Finally got it home , cleaned everything out , i thought waterpumps were ok, although port engine seemed to not be making pressure at idle. Next time out we had to idle through no wake zone that was pretty long and port engine again started heating up . Once on plane it was ok .
But on our way home that day got stuck on another sandbar briefly ,and you guessed it , port motor not flowing again.
So the next day I am pissed , and the wife is over boating and ready to sell , but I normally dont give up as easily , so i go out and start dismantling everything . I found the port pump housing to be scarred pretty badly. BUt i didnt stop there , i pulled all hoses off of oil cooler ,and upon inspection i noticed that about 30% of the flow through holes were completely clogged, and appeared to have been for some time. Im pretty sure this was contributing to my system clogging easily , and not flowing good enough at idle. Im actually going to go through all the steps of checking my starboard motor today , even though i havent had the problems , I dont want to chance another day of good boating.
BTW i used a coat hanger , and shaped the end like a drill bit to drill through the oil cooler holes.

wwwTOPDJcom

well I think I may have found the problem the elbow on the Sea strainer was very loose, I took it out and put about 7 turns of Teflon tape and now I don't see any air bubbles, I sure hope this is the end of this. BTW I back flushed the coolers and drained the block again everything was fine. I Pulled the new impeller and it still looked new
blades were still straight and pump housing was perfect.

Only thing I can think of is at high speed the boat overcame the air leak under the strainer.