Warning - Check Your Raw Water Filter

Richard10002

Richard10002

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A few weeks ago, the engine was idling at anchor and i heard the note change. Stopped it within seconds, found a plastic bag and some weed in the inlet filter, (thought it was a jelly fish at first). The impellor didnt look damaged, but I changed it anyway.

Arrived Syracusa nearly 3 weeks ago, noticed the occassional bit of weed floating past, so kept a religious eye on the exhaust water flow at start up - all fine. After a week, I checked the filter, and it had a bit of weed in it, but not much.

Continued to check the exhaust water flow... all seems fine. Checked the filter again tonight... choc a bloc with weed and mud... water was obviously getting through, but it must have been at a reduced rate, and it was only a matter of time before it clogged.

So... even if the exhaust water flow seems to be OK, it doesnt mean your intake filter isnt close to being clogged.

How often should we be checking the raw water filter, (probably every time you start the engine is the official line???).

Richard
 
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(probably every time you start the engine is the official line???).



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unless you have a particular reason then that may be too rigourous.

Once a day certainly though!
 
My main engine's raw water inlet and filter has a glass window and you can see the build up of any muck. I don't open mine very often and only then when I suspect there might be deposit on the mesh rather than bits of stuff.

The generator has one of those sticky-up filters with a screw cap on top and a cylindrical filter inside. Real pain.
 
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How often should we be checking the raw water filter, (probably every time you start the engine is the official line???)

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All the time the engine is running. Well, you can if you've got one of these fitted. And it'll warn you before you've cooked the impeller.
 
Very clean engine! I can just see me putting one of those together..... perhaps they should be sold as a kit, (with the circuit board ready made).
 
No they shouldent come ready made, then they would cost about £200.
No lets just continue to make up our own, like I did and am also making one for a friend to fit in his boat this winter.
I had similar problems to R_F_M44 last season, after advice from the forum and Steve, made up one.
Now the whole of the Firth of Clyde will know if the rw intake gets blocked. /forums/images/graemlins/laugh.gif
 
A passing observation.
These sensors use a plunger with a magnet, which is pushed up the tube by the water flow, activating a reed switch. If you get a marine creature moving in, it is possible to hold the plunger up, thus indicating that you have a flow.
Exhaust temp alarms, lost faith in them a few years back.
Had a Vetus engine with exhaust temp alarm, and funny thing we were out testing a raw water flow sensor. We were turning the raw water intake valve off, to duplicate flow loss. After a few hours testing we motored back home, it took about a mile before the alarm went off, we had forgot to turn water back on.
Has anyone tested there exhaurst temp alarm ?

Having a negative night.

Brian
 
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BTW, how do you pronounce your name?

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Some people pronounce it 'twat', but usually its 'Steve'. When I registered here all the 'Steve' permutations seemed to have been taken already, so srp are my initials, and 01983 is the Isle of Wight STD code. Someone here many posts ago thought it was something to do with my date of birth, sadly no, they were 30 years adrift.
If I get the chance, I'll machine out a few pcb's - if I do I'll post on here, in case anyone wants to burn their fingers with a soldering iron.
 
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(cut) If you get a marine creature moving in, it is possible to hold the plunger up, thus indicating that you have a flow.
(cut)
Brian

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When you turn on your ignition, there will be no flow so the alarm will self test before each engine use.

When engine starts, ign alarm will go off, then as flow is established, the water flow alarm will cease. If one is a squeal & one a buzzer, then Bob is your proverbial.

Well, at least that's the way I plan to set mine up. /forums/images/graemlins/cool.gif

Thanks for the bio inf, Steve - dead common name that innit?

Steve K (aka searush)
 
Exhaust alarms go off long after the flow has stopped and just before the engine is about to expire. A flow alarm gives a good warning. There was one to make in PBO last year. Flow switches are very cheap and any circuit that sounds a buzzer or siren will work. Do a search on this forum.
 
I am a bit paranoic about water flow since I had an incident! I now have a reasonably good set up. I have a Vetus viewable water trap which I have mounted outside the engine compartment behind the companionway steps. I can see the water flow and amount of weed every time I go in and out of the cabin. I next have a Halyard Marine water "flow" alarm which really does work. This is actually a water negative pressure alarm so that if there is a blockage at the intake, the impellor sucks a negative pressure and the alarm goes off. This is instantaneous. Lastly I have a Vetus exhaust alarm which did go off before I had the visible strainer and neg pressure alarm fitted, so that works. BTW it went off before any heat damage was done.
 
My gen set has a right hand bend just after the inlet skin fitting. This reduceds the bore so much that weed can get stuck in this. Had me very puzzled to start with, as I could not get water through, until I dismantled it. They had to do this because there is no room under the floor where they put it. Should change the location, as it will always be a source of potential trouble, notioced when the overheat alarm goes off.
 
I dont think checking the filter daily is to onerous a task. ONly takes a few minutes to give you some piece of mind. I do remember reading however that the water filter will still allow enough flow of water if its 80% blocked.
 
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How often should we be checking the raw water filter, (probably every time you start the engine is the official line???)

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All the time the engine is running. Well, you can if you've got one of these fitted. And it'll warn you before you've cooked the impeller.

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so why do you need it on a Yanmar which already has an overheat alarm to prevent damage built into its engine control ?
 
Do all you guys not have a little chap pishing out the side of your boat when the engine runs? The tell-tale/syphon break on my boat is very sensitive to flow, so when he has prostate problems I immediately check the temperature guage and then sometimes become a plumber...Some of them do it in the cockpit drain for easier observation. I suppose those of us with indirect cooling have a wee time delay before the smoke happens.
 
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so why do you need it on a Yanmar which already has an overheat alarm to prevent damage built into its engine control ?

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Because mine isn't an overheat alarm. It's a water flow alarm. I want to know before the engine overheats, not after.
 
Richard10002 said:
A few weeks ago, the engine was idling at anchor and i heard the note change. Stopped it within seconds, found a plastic bag and some weed in the inlet filter, (thought it was a jelly fish at first). The impellor didnt look damaged, but I changed it anyway.

Richard
Click to expand...

We got jelly fish, we removed them, fired up the generator again checking with hand on impeller casing on start up, cold so did nothing ( it was a new impeller two week prior)

It stopped at its own accord 'tellng, excessive steam through the dry exhaust' while we were getting the dinghy in."
 
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