cooling water pump flow rate

[gasdave]

I would like to try something I have not done before....

My boat is on the hard and I would like to turn the engine (Volvo Penta 2001) over and run it briefly. If I transfer the raw water cooling intake from the seacock to a bucket of water I believe this ought to be OK. My question is how long could I run it for before the water runs out (standard size bucket and all that!)? Anyone got any idea what the flow rate is for these pumps?

Is there anything else I should be cautious about with this plan?

Many thanks in anticipation as always

 

[pvb]

It won't run for very long on a single bucket of water, maybe a minute or two at idle. If you want to run it for longer, you could keep topping the bucket up with a hosepipe.

 

[VicS]

I would like to try something I have not done before....

My boat is on the hard and I would like to turn the engine (Volvo Penta 2001) over and run it briefly. If I transfer the raw water cooling intake from the seacock to a bucket of water I believe this ought to be OK. My question is how long could I run it for before the water runs out (standard size bucket and all that!)? Anyone got any idea what the flow rate is for these pumps?

Is there anything else I should be cautious about with this plan?

Many thanks in anticipation as always

What i have done is to stick the bucket in the cockpit with a hose running into it, and extended the pump suction up to the bucket. That way it can be kept running for as long as you can keep an eye on the bucket.

The necessary precaution is to withdraw the pump suction from the bucket when stopping the engine ( preferably just before) so that water does not continue to syphon into the exhaust system.

A local control valve on the hose is also useful.

Otherwise ITYWF that a single bucketfull is barely enough to be useful.

 

[NickRobinson]

Is anything valuable in line with your exhaust? When my seller demo-ed the engine on the hard, the yard owner's office window needed covering.

(Valid )Elf & Safety point, consider a spinning prop at arm's reach to kid's, dogs, others under your boat while you are head first and out of sight in a noisy engine hatch?

N

 

[vyv_cox]

There is a small study of this on my website here http://coxengineering.sharepoint.com/Pages/Waterpump.aspx about 2/3 down the page. At 1000 rpm Tim Rampton measured between 180 and 420 l/min, dependent upon cam wear in the pump.

My method is to use the reservoir of my Vetus strainer in conjunction with a hose pipe with pistol grip nozzle. It is not too difficult to keep the reservoir full but to the brim it lasts only a couple of seconds at fast tickover, about 1-2 litre capacity.

 

[gasdave]

Is anything valuable in line with your exhaust? When my seller demo-ed the engine on the hard, the yard owner's office window needed covering.

(Valid )Elf & Safety point, consider a spinning prop at arm's reach to kid's, dogs, others under your boat while you are head first and out of sight in a noisy engine hatch?

N

Good point about the exhaust - but in my case not a problem as there's just fresh air.

I would do this with the gear disengaged so danger from prop does not exist - although I agree it is still sensible to ensure that no-one is close to it "just in case".

Another thought/question:-
What would be the maximum length of hose I could use from bucket to pump to minimise any potential damage during the first few seconds while the hose deadspace is filling?
The currently fitted hose will need to be replaced for this job as it would not reach to where I could place a bucket, and the run to the bottom of a bucket in the cockpit might be at least 5' or 6' or so. I suppose I ought to prime this first before I dip it in the bucket?

 

[Seatrout]

Hi Dave... I have the same engine. Having changed all filters etc on the hard, I wanted a confidence level that it would fire before going into the water.
I removed the impeller and fired her up dry for 30 secs or so.... no problems.
Now in the water, (with impeller fitted), and she runs fine. I have sail drive and would have fitted water hose baffles if I intended running longer on the hard.

 

[nigelmercier]

One of the most useful mods I made to my engine is a T-piece on the water inlet, with a ball valve on the spur. This connects to a short hose with a screw fitting that replaces a blanking cap. If I want to suck water from a bucket, I connect the hose, close the seacock and open the spur.

 

[pvb]

There is a small study of this on my website here http://coxengineering.sharepoint.com/Pages/Waterpump.aspx about 2/3 down the page. At 1000 rpm Tim Rampton measured between 180 and 420 l/min, dependent upon cam wear in the pump.

That sounds an incredibly high flow rate! On that basis, a hosepipe wouldn't keep up with it.

 

[gasdave]

There is a small study of this on my website here http://coxengineering.sharepoint.com/Pages/Waterpump.aspx about 2/3 down the page. At 1000 rpm Tim Rampton measured between 180 and 420 l/min, dependent upon cam wear in the pump.

My method is to use the reservoir of my Vetus strainer in conjunction with a hose pipe with pistol grip nozzle. It is not too difficult to keep the reservoir full but to the brim it lasts only a couple of seconds at fast tickover, about 1-2 litre capacity.

Thank you for this reference, Vyv.
I note however that Tim's figures are 180 - 420 litres/hour - which seems more manageable to keep up with using your average hose. I assume that these rates must be engine size dependent, on the basis that a larger block requires more cooling water volume?

 

[vyv_cox]

That sounds an incredibly high flow rate! On that basis, a hosepipe wouldn't keep up with it.

Yes sorry, my mistake. Litres per hour, not minute. Must forget values of my previous employment!

 

[vyv_cox]

Thank you for this reference, Vyv.
I note however that Tim's figures are 180 - 420 litres/hour - which seems more manageable to keep up with using your average hose. I assume that these rates must be engine size dependent, on the basis that a larger block requires more cooling water volume?

I don't know what the engine was but he gives the pump dimensions, which presumably determine the rate.

 

[alan_d]

(Valid )Elf & Safety point, consider a spinning prop at arm's reach to kid's, dogs, others under your boat while you are head first and out of sight in a noisy engine hatch?

N

I have only ever known people do this with the gearbox in neutral, so no spinning prop. If you have a cutless-type bearing you certainly should not engage gear as without water for lubrication the bearing will be damaged.

 

[KAM]

If you have mains water its worth fitting a toilet ball valve (torbec) to the bucket and attaching the supply hose to that.

 

[gasdave]

I don't know what the engine was but he gives the pump dimensions, which presumably determine the rate.

I thought I would update the forum on this as I managed to successfully run the engine, cooled from a bucket of water today.

The 10hp VP 2001 drew 6 litres / minute running at 1000rpm - so this seems like a healthy cooling system to me when compared with Vyv's figures.

Incidentally Jabsco recommend a cooling water requirement of 45 litres / minute / 100hp for a directly cooled diesel engine and their pumps are fitted as standard to many marine engines (mine might be - forgot to look that closely). So this is reassuring too.

 

[alahol2]

I hang a bucket over the stern, directly under the exhaust outlet. A piece of heavy polythene taped around the exhaust outlet directs the exhaust water into the bucket. A hose runs from the bucket to the cooling water inlet under the boat and is jammed into the skin fitting. With an effectively closed circuit I can run the engine at tickover for as long as necessary. I do this to warm the engine oil before draining and to circulate a mix of water, antifreeze and oil before the winter layup.
I do as Seatrout does at the start of the season, ie remove the impeller and run the engine up for a minute or so to ensure it's going to run when we hit the water.