Impeller VP TAMD41P

As per our conversation make sure the sea cock inlet valve is in the off postion then poke the fresh water hose in to the strainer in the gearbox cooler side and start the engine so that it pumps water . The water should then fill the water strainer up as the engine pump does not suck up the water faster than water hose can deliver. Let the water keep filling the strainer up so it over flows now pull the hose out so that you are filling from the top of the strainer and then stop the engine but keep the water flowing. Yes i know the water will be going in to the bilge but as soon as you start the engine again it should start pumping again . I normally squeaze the pipe a bit to reduce the flow when the engine is running so that there is not to much water going in to the bilge.
The most inportant thing is to make sure you have that sea cock inlet valve closed or most of the water will be going on the floor as the boat is on the hard stand.
Before you but the boat in the water make sure the sea cock is closed and the strainer is full of water and the sealing cap is tight.
I have placed a link below with the style i have in my MF805 with the clear lid which makes it alot easer to see what is happening to the water .


VETUS water strainer - Cooling water strainers - Engines and around the engines
 
Thanks guys, I’ll give all this a try on Monday. The more I think about it the more I think all these problems started when I cracked the seal on the strainer. I’ll report back after some more trials.
Thanks again Jamie L for the chat on the phone, plenty to think about there. I assume the 51l/pm strainer works ok with this engine? I’m seriously thinking of changing to a strainer I can check without dismantling it.
 
Jamie Dundee said:
Thanks guys, I’ll give all this a try on Monday. The more I think about it the more I think all these problems started when I cracked the seal on the strainer. I’ll report back after some more trials.
Thanks again Jamie L for the chat on the phone, plenty to think about there. I assume the 51l/pm strainer works ok with this engine? I’m seriously thinking of changing to a strainer I can check without dismantling it.
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I think you need the next size up the FTR330/32. I have these supplying a KAMD 300 which has a very very similar cooling sustem to your 41s (I think). Check the internal diameter of the existing pipes/hoses going to the engine.
 
Back at the boat this morning and carefully primed the full system, closing the seacock and filling the strainer to overflowing. Got the lids good and tight on the strainer, primed the water pump and switched on. Success! Loads of water flowing out of the exhaust, job done. Increased the revs slightly and the flow instantly dwindled then stopped.

Went through the whole process again, success! Then I noticed something odd about the hose from the strainer to the gearbox and suddenly realised that the hose is transparent. There, inside the hose, was an enormous air bubble fizzing and bouncing around, just allowing enough water to flow to keep the pump supplied on tick over. Increase the revs and airlock.

So presumably all I need to do now is bleed the air from between strainer and gearbox and all will be ok?? Am I likely to need to somehow bleed the gearbox? The airlock appears to be only in the hose so fingers crossed it’s an easy fix. I might change the strainer while I’m at it for a more modern one which can be checked without dismantling. Anyone any idea of the flow rate required by this engine or can I just fit a strainer with the correct sized hose fittings?
 
Sorry Jamie
Something is wrong, I think you are still sucking in air from somewhere. When you first start up the engine, there will be some bubbles etc, but as you increase revs etc they will get sucked through with the water until there is no more air in the pipes. That happens pretty quickly. Also you should not have to prime or bleed anything - the whole system should self prime pretty much immediately.
There may be some air right at the top of the strainer, and the odd little bubble every now and then, What you seem to be describing is a situation where it is easier for the engine to suck in air rather than water. Try the new hose on the pump test with a bucket and go from there.

edit: have you checked the seacock is fully open/working correctly. The handle may be moving but the internals may not be. You need to take the hose of the seacock and open it slowly - water should pour in very fast. Dont worry you won't sink and it won't be a jet shooting up into the air. The pressure is very low. Just have it fully open for a second or two to make sure the flow is not impeded at all.
 
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kashurst said:
Sorry Jamie
Something is wrong, I think you are still sucking in air from somewhere. When you first start up the engine, there will be some bubbles etc, but as you increase revs etc they will get sucked through with the water until there is no more air in the pipes. That happens pretty quickly. Also you should not have to prime or bleed anything - the whole system should self prime pretty much immediately.
There may be some air right at the top of the strainer, and the odd little bubble every now and then, What you seem to be describing is a situation where it is easier for the engine to suck in air rather than water. Try the new hose on the pump test with a bucket and go from there.

edit: have you checked the seacock is fully open/working correctly. The handle may be moving but the internals may not be. You need to take the hose of the seacock and open it slowly - water should pour in very fast. Dont worry you won't sink and it won't be a jet shooting up into the air. The pressure is very low. Just have it fully open for a second or two to make sure the flow is not impeded at all.
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True I won’t sink as the boat is on the hard ;) The seacock is ok as water pours out of the skin fitting if I fill the strainer with the hose. I’ll have more time tomorrow for a proper play to get the air out but this is a huge bubble which appears to be trapped between strainer and gearbox. I’ll do some dismantling tomorrow and see where we go from there.
 
How are you getting water into the boat when it’s on the hard? If it’s a hose stuffed up the seacock, maybe it can’t keep up when you lift the revs and sucks air?
 
I cannot believe your telling us the boats out the water and your having these problems , more to the point why hasn’t your so called engineer told you why it won’t suck water !!!!! .
every time you stop the engine the water drains back causing an air lock , because it’s out the water there is no way it can suck water uphill with air in the pipe.

when the boats in the water you get a positive pressure right up the pipe to the waterline , it’s called physics .
so you’ve had us all going here trying to solve the issue with it out the water .

ill get my coat .
 
volvopaul said:
I cannot believe your telling us the boats out the water and your having these problems , more to the point why hasn’t your so called engineer told you why it won’t suck water !!!!! .
every time you stop the engine the water drains back causing an air lock , because it’s out the water there is no way it can suck water uphill with air in the pipe.

when the boats in the water you get a positive pressure right up the pipe to the waterline , it’s called physics .
so you’ve had us all going here trying to solve the issue with it out the water .

ill get my coat .
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Worked every week for three months until I dismantled the strainer. Perhaps physics only happens occasionally.
Force 4 Universal Inboard Engine Flusher | Force 4 Chandlery
Presumably with the hose in the strainer it’s also trying to suck water uphill?
 
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Plum said:
What strainer do you have?
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It’s a black plastic strainer with an inner basket which has a rubber seal upon which sits a black plastic plate. A solid black plastic lid then screws onto the top. The inner plate creates a vacuum, the problem is that you have to take the strainer apart to check the basket. I think I’ll change to a Vetus strainer with a clear lid.
 
That sounds like the original VP strainer Google Image Result for http://www.ropewalkmarine.com/images/thumbs/0003135_300.jpg . I had the same problem as you. It was the lack of a good seal between the body, the basket and the flat plate. The screw lid does not have a seal, the seal is made by the screw lid forcing the flat plate against the soft plastic rim of the basket which also has to seal against the sides of the body. I solved the problem 3 years ago by fitting a flat perspex lid to the existing VP body with a rubber seal between. Now I always get a good seal, the pump always self primes and I can see inside.

Www.solocoastalsailing.co.uk
 
Plum said:
That sounds like the original VP strainer Google Image Result for http://www.ropewalkmarine.com/images/thumbs/0003135_300.jpg . I had the same problem as you. It was the lack of a good seal between the body, the basket and the flat plate. The screw lid does not have a seal, the seal is made by the screw lid forcing the flat plate against the soft plastic rim of the basket which also has to seal against the sides of the body. I solved the problem 3 years ago by fitting a flat perspex lid to the existing VP body with a rubber seal between. Now I always get a good seal, the pump always self primes and I can see inside.

Www.solocoastalsailing.co.uk
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That’s the one. Think I’ll get a Vetus strainer and kill two birds with one stone.

I’m aware I caused the airlock problem by taking the top off the strainer, but as a new boat to me I wanted to check there were no hidden problems before launching. Good to know I’m not the only owner to have this problem.
 
snowbird30ds said:
I have fetus strainers and leave some plastic balls in there as it makes water flow more obvious, the balls were from a game.
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Wont help with mine as the strainer and lid are black plastic.

Had it running yesterday, tracing the bubbles back up the hose from the gearbox it looks like the strainer isn’t sealing properly. I’ll replace it with a Vetus strainer, hopefully will solve the problem.
 
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