Fitting raw water filter

Engine is Yanmar 3gm30f and idea is also to fit an extra intake hose from bilge so I can use water pump on engine as an extra bilge pump.
 
Ex-SolentBoy said:
Not sure what engine you have, but that filter is not really meant for engines.
Click to expand...

Indeed not. These are raw water filters.

As for using the raw water pump as a bilge pump, it doesn't sound a good idea as
a) the pump capacity is low and
b) oil, sediment and other rubbish out of the bilge will be pumped through the engine
 
That particular strainer is for bilge pump and general plumbing applications. It has too small a filter surface area to be used on an engine. Look at the Vetus 300 also on that site - that's for raw water intake on engines. You can get many versions but they should have a screen no finer than 1/8" and a large filter area.

I'm surprised your raw water intake has an anti siphon valve - very unusual on this application. It's usually seacock, strainer, pump with the shortest route between each. This is the recommendation of Jabsco.

Using the engine pump as a bilge pump has been discussed on here before, some like it, some not. I would not use such a system because it has the potential to introduce another problem, overheating engine, into an already bad situation.
 
Yes, not a good idea to use the raw water pump as a bilge pump. Better to have a separate engine driven pump if you want extra bilge pumping over the normal manual and electric pumps.

If you are going to try using it for that purpose then you need a Y valve in the intake seacock and your existing water strainer (if you have one), so there is no need for an extra strainer to protect the engine. However, given the flow requirements of the engine (up to 50l a minute) you would empty a bilge pretty quickly and run the risk of sucking air. Any antisyphon valve is fitted after the raw water pump.
 
The item in the Force4 catalogue is the Water Inlet Strainer(640040) @ £24.95 this has connections for all three sizes of hose connection. Flow rate is 150 ltrs/min


The Vetus ones they have @ £96.95(in 3/4",1" and 1 1/4") sizes so you'll need to know which one you require.Flow rates are 120 litres/min; 210 ltrs/min and 330 ltrs /min.(64009/10/11) in the catalogue


I have the first item for my VP2010, find it very good and easy to service regularly,but may not be sufficient flow rate for your larger engine.Mount this strainer at least 8" above sea level. I mounted mine inside the front of the engine compartment for easy access and cleaning. A smear of grease in the threads will avoid the need to screw up bar tight and a 'key' to remove the lid when cleaning it.

ianat182
 
As said use a filter intended as a cooling water intake strainer .
Vetus catalog page 60 et seq. http://viewer.zmags.com/publication/06fa8bec#/06fa8bec/60


The antisyphon valve in the cooling system should NOT be fitted in the suction side of the pump, neither before nor after the strainer. Air will be sucked in if it is, reducing the pump performance and affecting the cooling.

It is most usually fitted between the engine and the water injection point into the exhaust system.
It can be, and in the case of some engines must be, fitted immedeiately after the pump if there is a suitable hose to re-route to it. ( some Volvo engines are like this)

There are illustrations of how an antisyphon valve should be fitted in the Vetus catalog on page 68 and 78
http://viewer.zmags.com/publication/06fa8bec#/06fa8bec/68
http://viewer.zmags.com/publication/06fa8bec#/06fa8bec/78
 
Last edited:
Thanks everyone.
Of course you are right, the anti siphon is after the pump.
Presently there is no raw water strainer (apart from the sieve mounted over the intake). So will want to mount one to protect pump and impeller in any case.
From memory the capacity of the pump is 70 l/h, so the one suggested by ianat182 might do the job nicely.
Btw why must it be mounted above sea level? This would mean quite a long extra length of hose as top of engine compartment is below sea level.
Brgds
Leif
 
Leif-J said:
Thanks everyone.
Of course you are right, the anti siphon is after the pump.
Presently there is no raw water strainer (apart from the sieve mounted over the intake). So will want to mount one to protect pump and impeller in any case.
From memory the capacity of the pump is 70 l/h, so the one suggested by ianat182 might do the job nicely.
Btw why must it be mounted above sea level? This would mean quite a long extra length of hose as top of engine compartment is below sea level.
Brgds
Leif
Click to expand...

my strainer is directly affixed to the seacock therefore below the water line, as long as the cock can isolate the strainer that is job done
 
The advantage of above the waterline is that it can be checked and cleaned without shutting off the seacock. Also useful (but not always possible) to mount immediately above the inlet so that you can clear any obstructions to the inlet easily. Such strainers are pretty much universal fitting on new boats these days.
 
Here on the R. Hamble I am frequently required to clean out the inlet piping and seacock of baby mussels and other debris sucked into it by the powerful raw water pump, and if left for any longish period of time in summer months; so I have obtained some 2ft flexible rod(curtain wires work well) and a wire bristled brush to clean the piping itself. I had occasion to do just this last week,spotted early by steam from the exhaust and very little water ejected;the filter was perfectly clear.
It isn't always an advantage to have a grill or mesh on the outside of the inlet as the barnacles and mussels will be impossible to shift from inside, mine is an open version.
Incidentally Vetus recommend the strainer to be above water level.

ianat182
 
Well, seems I will have to consider removing the mesh on outside then. Sounds like a good idea ianat182.
Just another boat task to do! :rolleyes:
 
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