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Old 02 May 2019, 05:23   #11
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Bit of an odd one & be interested to hear the solution
Me too dude!

Thanks all for the above replies - a couple of things for me to look into.

I ran the engine up before launch this year by inserting a garden hose directly into the water outflow in the strainer basket. Everything seemed normal and to my regret, I didn't haul out the 300L tank for a full run up test. Water seemed to pump out via the exhaust/leg as per normal (I have a video) and I could actually hear the suction at the basket end. On killing the motor, the water filled the system and back flowed into the basket and then ran freely back out through the leg inlet pickups (as per previously). That's an average hose worth of water freely draining out via the pickup - so I guess the pickup passages from the leg to the basket are not SNAFU. The basket lid seal seems to be the obvious goto but I had checked the seals, put a little vaseline on them and was particularly careful to seat the lid properly. No bubbles are being created inside the basket when running and the system is holding water up when not running. Kinda leaves the pump/outlet side. I'm afloat now on a mooring and I have clients next week so having run at WOT and done an hour at 30kts without temperature issues I will have to wait for further tests. That said, I hate a Mystery

Ken - the pump on the V8 is a bggr to get at. There was a leak due to (I think) a damaged bearing/seal on the pump shaft. Yanmar were kind enough to replace the shaft out of warranty and the decision to remove the engine will not have been taken lightly.
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Old 02 May 2019, 06:03   #12
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Sounds like Yanmar excelled in making pump access hard this time. The 6lps & 4lhs were bad enough located to change impellers. I usually end up taking the pumps off my 6lps to change the impellers but at least you can get them of in situ
Lets hope its something relatively simple
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Old 02 May 2019, 12:08   #13
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Willk - agreed, I had exactly the same with my basket lid seal last year, and assumed that was your problem, but reading the rest of your post, seemed not! Sadly I can't find an exact replacement seal for mine, so still being very careful with the old one currently. I need to hunt around again... We shall all be enlightened when you find the issue :-).

Beamishken - yes, whilst the 6LP isn't the best design, at least you can fairly easily remove the whole pump to change the impeller! Once you've worked out by feel where the bolts are, and what socket extension to use whilst hanging upside down in the engine bay... Sounds like a big job, but actually makes it a darn sight easier than trying to replace the impeller in situ. Another reason to stay with my 6LP :-).
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Old 02 May 2019, 14:32   #14
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willk, I've been pondering your engine problem, if there is definitely nothing awry with the engine removal and refitting then looking at the pump for an issue as the first option might be wise since everything was good before. The pump has to be capable of sucking air to evacuate the air in the pipe in order to suck and lift the water, if the impeller is not good fitting it won't be able to do this although it may well be able to pump water once primed. I was considering the impeller and thought that perhaps it was possible to inadvertently fit a shorter impeller maybe just a millimetre shorter, just enough to let the air pass the blades but not easily noticeable in fitting, but then it occurred to me that my Volvo pump and possibly with your pump too, inside the bottom of the pump housing is a plate, a bronze plate kinda like a big washer, I think it's just a wear plate to save the pump housing, if this plate has been omitted from the pump it would give a little bit of end clearance on the impeller which would allow air to pass from the front to the back of the blades and make pumping air pretty tricky if not impossible. Just a thought for you, it's an easy check if you can get at the impeller. I realise your pump is well hidden but if you can get the cover plate off...of course the impeller should be slightly compressed in there.

Re your vaseline on the seal, it's normally considered poor practice to use petroleum products on rubber. I've no idea about the compatibility in your case but I'd be using rubber grease rather than Vaseline. The red stuff commonly used for vehicle brake rubber's lubrication would by my choice, simply because I have a big tub of it.
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Old 02 June 2019, 15:22   #15
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Willk - did you get to the bottom of this?
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Old 02 June 2019, 15:40   #16
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Willk - did you get to the bottom of this?
I did. The rebuilt water pump was failing and subsequently calved offshore. My engine is currently back on the concrete and RBB are wrangling with Barrus who appear to be somewhat embarrassed in the spare parts department. I observe with trepidation as I'm due to take a squad of lads to Islay and the SIB isn't the boat for the job!
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Old 11 June 2019, 15:35   #17
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Well credit where it's due - all involved got behind this one and gave it a big shove forwards - thanks all round. The willkcraft slipped back into the Irish Sea on Sunday at noon and was home on her mooring on the NW coast a few hours later. She has a Date with Destiny shortly, so I want her at her best...

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Old 12 June 2019, 02:44   #18
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Good to hear it is sorted.

On my Pac 22, the Mermaid Turbo 4 had a bronze impeller water pump made by a firm in the Lake District called Gilkes.

It was basically fit and forget plus it gave the ability for the engine to be run out of the water for five minutes.

I've changed (am still bloody changing) the engine to a Yanmar (4LHA) and I asked Gilkes whether they did a conversion for a Yanmar engine to which they said no.

I also help out with my local independent lifeboat (apologies if you are reading this - I'm a bit busy at the moment but will be back down soon) and I think it would be handy if they could flash up their engines (twin 8LV's) prior to entering the water.

I'm probably fretting about nothing but does anyone know of alternatives to the standard impeller?
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