Hi,

New here so please bare with me if I should violate any unwritten rules

We have an old Nordic 79 (from 1976) with an AQ131D Volvo Penta 2.3 (B230) and Volvo Penta 275 Z-drive.

I have tried all I can think of regarding the seawater impeller pump (except a new one which so far I can't find) ... yes... priming pump before use and greased the new impeller (in fact 2 new until now) but the pump just doesn't seem to be able to deliver enough seawater throughput...

In desperation I mounted an electric impellerpump right where the first rubbertube is mounted on the stealtube comming from the Z-drive.
I removed the impeller from the original housing thus just mounting the axle (to keep it sealed).
The pump delivers 28 litres per min. at 1 bar.
So far I have only run the engine in idle but it stays very cool so the cooling works like a charm.

I guess my question is... how much seawater throughput does the original impellerpump deliver at max.?

My test setup has so much "force" that the original (all new) seals can't hold the water 100% ... the seals leak... so at idle at least, I must have much more seawater throughput than under normal conditions.

Anyone have the answer or perhaps have converted to electric impellerpump?

And yes... I know that I have to start the pump AFTER I have turned on the engine and stop the pump BEFORE I stop the engine

Thanks in advance

 

I would work on getting the engine driven pump to work properly. When you installed the new impeller did you bend the blades in the right direction:as you installed it? When you first decided to replace the impeller were all the blades intact in the old impeller or had one broken off and is stuck in your cooling system? Is the impeller housing so worn that the impeller does not make a good seal (sides of impeller)? Lastly could the v-belt or pulley spinning the pump be slipping?

 

Hi "DTD"?

Thanks... all good ideas/thoughts but... well... I'm way past "let's try to fix the original pump" point...
1) yes I have mounted the impeller in the correct direction.
2) yes I have greased the impeller before I mounted it.
3) yes I have checked the old impeller for damage (none).
4) yes I have checked, cleaned and pressure tested the heat exchanger/cooler (no big fragments found).
5) yes I have changed all seals (not only in the impeller housing).
6) yes I have checked the housing for damage (little scoring damage on the "lid") but I have had NO luck finding a replacement. It might be possible to mill the surface but I'm afraid the axle would not fit afterwards... but plz. read #7...
7) yes I have lost any and every confidence ind the Volvo Penta impeller pump and seawater setup in general on the old AQ131D engine.

#7 is the main reason for my question for which I seek an answer.
I appreciate your time and care but you didn't answer my question ;-)

So... to elaborate... I can't grasp why Volvo would place the seawater filter AFTER the pump. All impeller pumps you buy today require a filter BEFORE the pump. Next I really don't like that it's not possible to (in any way) tighten fittings going in or out of the seawater system except on the "suction-side" and here the margin for error (air leaks) is very small.

As I can't find what I need or don't want to pay a fortune, I'm trying to improve my setup.
For that I need to know what minimum and maximum throughput the original impellerpump can deliver.

Thanks for your time and hoping for an answer to my original question :-)

EDIT: Sorry, didn't answer all your queries... no the belt is not slipping. All belts tensioner and such is new also all seals... and btw. the seawater pump (impellerpump) is not driven by the belt but rather directly on the engine... and yes... it is turning as it should, must, can't really not ;-)

Best regards
Kim Enemark (as my username states )

 

I seem to remember a boat I had 20+ years ago with a VP outdrive where I complained (to myself) that the filter only caught coarse things and smaller stuff (like sand,) would pass through the filter but clog up the heat exchanger. As I remember we brought the heat exchanger to a radiator shop and had them clean it. Unfortunately with aluminum and plastic radiators in cars these days people just replace a radiator rather than having it repaired. So fewer radiator shops around these days.

 

I come back to 'it must have worked when new, so what has changed?"

 

Hi sir,

no need to quote all my text in every reply and I hear you and I understand you, but that's not really what I ask ;-)

Best regards
Kim Enemark

 

My guess is your electric pump is pumping at a higher PSI or more GPM than the stock setup. The real problem is your heat exchanger is partially clogged but the electric pump can move enough water to overcome the clogged heat exchanger but stock raw water pump cannot.

 

Thanks again and you may very well be right but that doesn't change the fact that I also may have an impellerpump with defect "lid" that maybe also should be renewed or machined/milled and the overshadowing fact that it doesn't answer my question ;-)

Regards
Kim Enemark