3116TA water pump impellers

[margarita jane]

with excellent advice and tips from CSR members changed out impellers(to get baseline since last impeller change was a guess from former owner) on new to me always freshwater SR400DA all went well....BUT stb. engine had 75% less flow(strainers appear to be clean) before change out and appeared to be same after change....impellers were 100% intact but had a lot of checking and stb.engine vanes were deformed more than port engine...stb. engine runs 10F(180) hotter but never varies,except cooler when not loaded....anyone offer explanation/opinion? also noticed port engine(the one that pumps water like a 3" fire hose) at idle bubbling/or burbling water from underwater exhaust and nothing on stb side, which I never noticed before change out...thoughts?

 

[fwebster]

The plumbing difference (longer runs, more bends,etc) between the port and stbd sides can effect the amount of water expelled under the boat vs. the ehaust overflow on the side above the water line. You may not have a problem.

However, if one heat exchanger is clogged with normal marine deposits or from impeller chunks you didn't retreive or old zinces that a previous owner has just shoved into the heat exchaanger when they broke off, then flow will de diminished. The only sure way to tell is to measure the pressure in the sea water system after the heat exchanger. The easiest way is to pull one of the zincs out of the transmission oil cooler and attach a glycerine filled low pressure gauge at that point. Pull the same zinc on both sides. Then, run both engines and note the pressures........the total pressure isn't material.....you are looking for the differential between the engines. This takes a little effort, but cleaning the heat exchangers costs about $1800...IF yours can be done by removing the tube bundle from the housing on the boat, and I don't think you can on a 400DA, your whole heat exchanger will have to be removed.

 

[Four Suns]

Is there a marine growth problem up on Lake Huron that requires one to clean heat exchangers? Do those Zebra Mussels clog up cooling systems or is that not as issue? Do you even have to use engine zincs?

 

[Warren]

Good point Gary but, yes, zincs are necessary on the Great Lakes although the life of zincs is greatly extended. Zebra mussels will not pass through the raw water strainers.
Cheers,
Warren

 

[tobnpr]

Are you saying that the stbd. engine runs 10 degrees hotter now, since the change-out-and they were running the same temps before?

 

[Jaws]

As Warren says, the life of zincs in fresh water is greatly extended. In previous boats I did more harm than good in checking old zincs and having them break off. I just should have left the darn things alone.

James

 

[margarita jane]

Are you saying that the stbd. engine runs 10 degrees hotter now, since the change-out-and they were running the same temps before?

have not had chance for water test since change out,to check temps, just figured with new impellers that flows would be more equal but as Frank says piping configuration or partially plugged HX could account for different flows.....thanks for input,all... Tom