Engine raw water pump not priming

[BabySharkDooDooDooDooDoo]

Lift in day yesterday and we had to pour water down the raw water strainer to encourage the water flow to go through the system and come out of the exhaust.

This happened for the first time last year without any recurrence while the boat was afloat. Never had the problem on previous boats either

Is this an early sign of future problems or just one of those things that happens from time to time?

Engine is Yanmar 3YM20 with saildrive. Impeller looked fine and no blockages at the water intake.

 

[pvb]

Is the lid of the strainer sealing properly?

 

[Stemar]

I had the same problem and it turned out that the intake and engine were fine, but the exhaust elbow water outlets were completely blocked. An overnight soak in brick cleaner and normal service was resumed.

 

[BabySharkDooDooDooDooDoo]

Is the lid of the strainer sealing properly?

It looks fine and I did try taking the lid off and reseating it but without success - might try putting some grease round the rubber seal next time around.

I had the same problem and it turned out that the intake and engine were fine, but the exhaust elbow water outlets were completely blocked. An overnight soak in brick cleaner and normal service was resumed.

The engine is only a couple of years old so hopefully that isn't an issue. Nothing noted in the service carried out just before lift out in late February.

 

[Rafiki]

I've had the same thing in the past on lift-in. It didn't recur during the season so I didn't worry about it.

 

[Caer Urfa]

You do not say IF the pipework after the filter but before the pump was drained or had water in it.

If it was drained out for winter/ashore etc then when you started up first time you were just sucking air, hence you say once water had been poured down she ran ok.

Other suspects as others say above,check filter cap rubber may be twisted or worn, check raw water intake pipe between seacock to filter, and discharge elbow

 

[BabySharkDooDooDooDooDoo]

The seacock was left open so I would expect most of the water up to the strainer to have drained away when the boat was lifted out.

However about a stainer full of water escaped from the impeller housing when I look the cover off to check it

 

[johnalison]

When this happened to me it was the pump that needed replacing, though it was a lot more than two years old.

 

[Graham_Wright]

It has just happened to mine. There was a crack in the suction hose.

 

[RichardS]

Lift in day yesterday and we had to pour water down the raw water strainer to encourage the water flow to go through the system and come out of the exhaust.

This happened for the first time last year without any recurrence while the boat was afloat. Never had the problem on previous boats either

Is this an early sign of future problems or just one of those things that happens from time to time?

Engine is Yanmar 3YM20 with saildrive. Impeller looked fine and no blockages at the water intake.

My two saildrive 3YM30s are exactly the same after a lift out, although sometimes it is one engine that fails to prime and sometimes the other. It has never been both.

I'll bet that if you slap plenty of silicone grease on the impeller before you launch, the pump will re-prime without a problem. This is what I do as it saves faffing about with the water jug whilst the travel hoist operator is waiting for me to drive off the straps.

Richard

 

[PetiteFleur]

This also happened to me a few days ago, new impeller fitted with plenty of the glycerine lubricant as supplied - stopped the engine and filled the pipe from the strainer to the pump. Checked the strainer lid before doing this but was well lubricated and tight. First time it's happened to me, always pumped straight away after winter.

 

[BabySharkDooDooDooDooDoo]

So its a "feature"

Next year I will try to remember to prime it before hitting the start button

 

[jwilson]

Happens almost every year with my shaft drive 3YM30 after a winter ashore. Once primed is OK.

 

[pvb]

So its a "feature"

Next year I will try to remember to prime it before hitting the start button

It might just be worth checking that your strainer is correctly plumbed. They usually have one pipe extending upwards inside the strainer - this should be connected to the inlet seacock. The purpose of the extended pipe is so that the strainer ends up full of water, this helps to get the pump running properly after launching.

 

[RichardS]

It might just be worth checking that your strainer is correctly plumbed. They usually have one pipe extending upwards inside the strainer - this should be connected to the inlet seacock. The purpose of the extended pipe is so that the strainer ends up full of water, this helps to get the pump running properly after launching.

I guess that you would know if it was plumbed the wrong way round as you would never have anything in the strainer. Even in the crystal clear Med I still find the odd bit of seaweed in there every season.

Richard

 

[NormanS]

I don't want to sound too smug, but although I always change the oil and the oil filter just before lift-out, I leave the fuel filter change until shortly before launching. Having changed the fuel filters, and replaced the seawater pump impeller after its winter holiday, I then give the engine a run just to make sure that all is well. I have a bucket with a hose attached, which gets stuffed into the engine inlet skin fitting. The bucket is suspended at about the height of the waterline, and a hose feeding the bucket. This replicates reality. Having checked that all systems are go, prior to launching, saves a lot of stress.

 

[jwilson]

It might just be worth checking that your strainer is correctly plumbed. They usually have one pipe extending upwards inside the strainer - this should be connected to the inlet seacock. The purpose of the extended pipe is so that the strainer ends up full of water, this helps to get the pump running properly after launching.

Interesting: my Vetus strainer is as fitted when the boat was new - but I'll check that the inlet does go into the "basket area". I have never found anything in the basket in 13 years, but there is a slotted peardrop inlet fitting on the hull that will keep out most weed.

 

[Halo]

My 3YM30 needs priming on launch. Once in the water I find it helps to open the sea cock to let sea water fill the space under the sea cock , close the sea cock, fully fill the strainer and re seal before opening the sea cock. If there is no seal the sea water fully drains you can see it through the lid and know you have to start again.

My strainer is a Vetus type 140. The O ring on this is 80mm id and 4mm thick. You can get spare o rings of this size cheaply and it helps replace them after a few seasons.

 

[pvb]

My 3YM30 needs priming on launch. Once in the water I find it helps to open the sea cock to let sea water fill the space under the sea cock , close the sea cock, fully fill the strainer and re seal before opening the sea cock. If there is no seal the sea water fully drains you can see it through the lid and know you have to start again.

My strainer is a Vetus type 140. The O ring on this is 80mm id and 4mm thick. You can get spare o rings of this size cheaply and it helps replace them after a few seasons.

I suspect your strainer is incorrectly plumbed. The pipe from the inlet seacock should go to the connection which has a pipe extending upwards inside the strainer, to within about 20mm of the top. If you fill the strainer with water, the only way it can empty is via the connection to the raw water pump. See the diagram in the manual...

https://www.vetus.com/media/wysiwyg...gine/Installation_instruction_type_FTR140.pdf

 

[Halo]

I suspect your strainer is incorrectly plumbed. The pipe from the inlet seacock should go to the connection which has a pipe extending upwards inside the strainer, to within about 20mm of the top. If you fill the strainer with water, the only way it can empty is via the connection to the raw water pump. See the diagram in the manual...

https://www.vetus.com/media/wysiwyg...gine/Installation_instruction_type_FTR140.pdf

Perhaps "fully drains" was a bad choice of words. The draining I was referring to is back down the inlet pipe so the water level in the strainer is level with the top of the inlet. If the seal is not good what you see is much more water has drained than the normal "bubble" of air which results if the strainer has sealed.