Question for the inboard engine crowd.

[willk]

I had my engine removed last winter to replace the shaft on the water pump. On returning to service, I find that the plant is VERY reluctant to fill the raw water system after launching. I've had a couple of runs at it and worked around the issue by feverish water priming from buckets via the strainer basket and a rev in neutral. Once running, ops seem normal with visibly good circulation and normal temps under way and at idle.

Previously the system sucked in raw water without issue and filled the strainer basket in seconds. Other than the water pump replacement/engine out, I'm doing all the same stuff. The system is holding the water in place above sea level when the engine is off, so I'm not liking air leaks for the cause. I don't see any bubbles appearing in the strainer basket.

I don't like a mystery

[Pikey Dave]

Didn’t you antifoul recently? Did some get where it shouldn’t have?

[willk]

Originally Posted by Pikey Dave

Didn’t you antifoul recently? Did some get where it shouldn’t have?

I certainly did and I don't think so. I remove the intake covers as part of the prep, clean the first few inches of the intake passages and a/f the whole plant, using a sponge on a wire. No sponges were lost in this process. It's entirely possible there's a mussel up there somewhere but no sign of overheating per se. As the engine was out, one would hope that any wildlife got the shove, but it's on my List of Questions...

[Last Tango]

"Teaching granny how to suck eggs"

But you did get the impeller vanes pointing it the right direction as you fitted it?

[GuyC]

Is the valve on the sea inlet fully open?

[willk]

Originally Posted by GuyC

Is the valve on the sea inlet fully open?

No valve - direct feed from leg! Thanks though - keep the ideas coming lads

[willk]

Originally Posted by Last Tango

"Teaching granny how to suck eggs"

But you did get the impeller vanes pointing it the right direction as you fitted it?

New impeller fitted. Same mech as last few services. Possible but VERY unlikely.

[jwalker]

Disconnect the raw water inlet, get a hose to it and back flush to check the flow back to the leg. If ok, connect the pump inlet to a bucket of water, start the engine and it should sook it up pronto. If both of those are good then swear a little and you'll need to check the outlet flow from the pump because if the water can't get out freely, it can't get in also. Report back.

[paulbrown22]

Agree with JW - test the pump directly with a bucket if possible to rule out the rest of the inlet/strainer system, and check if the refurbished pump itself is good. I assume the impeller that was removed and replaced was whole, and no blades had been lost into the cooling system? Or potentially the new impeller has suffered infant mortality and popped a blade or two immediately?

[beamishken]

I assume the zt370 only picks up via the leg and isnt tee'd to a through hull like the 6lp and bravo? Hopefully the inlet hose through the shield is larger on the zt as its woefuly inadequate to cool a large engine on the bravo. Could the problem be a displaced seal in the joint between the drive and shield? Or could there be a part corroded pencil anode dropped into the heat exchanger when being replaced?
I'm finding it hard to comprehend that the engine needed to come out to work on the rwp? Isn't it accessible in situ?
The impeller vanes backwards is a red herring they flip the correct way as soon as it starts to turn
If it was an older engine I'd be suspecting a possible worn pump/end plate but on something as new maybe not and presumably the engineer had a good look at the pump while it was off.
Bit of an odd one & be interested to hear the solution

[willk]

Originally Posted by beamishken

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.

[beamishken]

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

[paulbrown22]

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 :-).

[jwalker]

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.

[GuyC]

Willk - did you get to the bottom of this?

[willk]

Originally Posted by GuyC

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!

[willk]

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...

[GuyC]

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?

[bullionbill]

Hi Just noticed your post

I have Pac 22 with 4LHDTE Yanmar which has Gilks raw water pump as standard

Bill

[GuyC]

Bill - thanks for the post.

If you have pic's or even better some model details, that would be great.

Are there any other ex MoD Yanmar engined Pac 22's out there with Gilkes water pumps on them?