Water pump insufficiency 3YM30

farmer.leo

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The engine was not spitting out water upon start up so was immediately shut down.
The impeller looks visibly OK though was not removed for more inspection.
Raw water can pass OK to the start of the raw water pump (tested with manual pump).
Removing the cover and cranking engine for an instant shows the impelling rotating correctly.

Manually pouring water through a funnel into the raw water pump inlet hose enables starting with normal appearing water spitting out exhaust.

This narrows the problem:
The pump fails when inverting the raw water pump's inlet hose into a bucket of water - no water spits out the exhaust. The pump clearly should have enough suction for this.

I'm new to engines, particularly diesels, so I didn't take the pump apart yet. What should I be looking for? Is there a specific deflection / tension the v belt to the raw water pump should have? How do I extract the impeller without damage (for the future, this one has got to go after all this testing) for inspection? The engine manuals I downloaded tell what to do, but don't describe how.
 

charles_reed

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If your filter is above the waterline, first check for an air-leak, usually caused by a badly fitting O-ring on the lid.
Turn off the sea-cock, fill the filter, turn on the seacock and start the engine. See how long the water flows.
The alternative, a frequent problem on those Jabsco pumps, it that the brass socket has come unbonded from the rubber outer of the impeller, with no load it looks OK and revolves, but with the faceplate on it just doesn't move.
The final, and most expensive, is wear - if on the faceplate turn it round, if in the body have it machined.
 

farmer.leo

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If your filter is above the waterline, first check for an air-leak, usually caused by a badly fitting O-ring on the lid.
Turn off the sea-cock, fill the filter, turn on the seacock and start the engine. See how long the water flows.
The alternative, a frequent problem on those Jabsco pumps, it that the brass socket has come unbonded from the rubber outer of the impeller, with no load it looks OK and revolves, but with the faceplate on it just doesn't move.
The final, and most expensive, is wear - if on the faceplate turn it round, if in the body have it machined.

My water bucket test shows the problem is from the pump forward: the pump can't draw from a buck of water that is right next to it - yet it works if feed water poured via a funnel into the feed hose.

So it's not the filter / strainer.

It's also not the socket / inner core of the impeller separating from the rubber part, because there is a bolt which runs through the center of it including the rubber part.

The faceplate and the body both look OK.

I checked the V-belt and it looks to be similar tension to the alternator belt.
 

talltim

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in addition the above air leak on vacuum side it sounds like it could be a worn impeller, body or cam to me.

All of which will result in reduction of suction

you could try giving engine a rev and see if this helps the pump to prime or packing the pump with vaseline
 

farmer.leo

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If your filter is above the waterline, first check for an air-leak, usually caused by a badly fitting O-ring on the lid.

Yes, the strainer is somewhat high above the water line, with a good length of drop to the raw water pump.

I saw and felt the o-ring completely around the pump, it definitely protruded from the indentation in which it resided. How closely do you check it? Must it be even all around? I'm going on memory now, but it might have been thinner at one point, yet still standing above the brass rim to touch.

How do you test for an air leak?
 

anniebray

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I have the same engine with saildrive, new in 2008. Raw water filter was below water line & I had pump priming problems after just 12 months. The raw water piping was incorrect spec....PVC which flattened on bends which was changed to rubber reinforced but still suction was weak. I noticed a bend in the raw water piping between the pump & filter where I visualised there could be an air pocket so I punctured the pipe at top of bend, bled out the air & got the pump primed. The pipe was so thick & reinforced that there was no leakage after withdrawal of the puncture tool. However just like your experience, the pump would not draw from an adjacent container when being serviced in our yard which was not acceptable. My problem was solved by fitting a new pump which a Yanmar agent said was expected after 450 hrs. My boat is a shallow draught twin keeler & I reckon that I probably got accelerated wear by using the engine to force the boat off in grounding situations. Bear in mind that my water inlet is thro the saildrive leg so low down & near the prop which churns up an abrasive mixture of sand/mud & water in the shallows. I have now rerouted water intake thro a new hull fitting.
Re your pump belt.....this should not be nearly as tight as your alternator belt. You will get accelerated pump bearing wear by overtightening.
 
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Are you really a farmer, Leo - farmers are in my experience very practical guys who can turn their hands to almost anything.

Anyway - you should be able to see if your pump is roitating when the engine is running and the drag on the pump isnt such as to cause belt slippage unless the belt is really slack or very ill fitting. Try turning the pump by hand with the engine stopped. If you can turn it then the belt is too slack.

If the belt is OK then check the hose from the pump to the water supply. Dont worry about the hose after that - if there is any leak there you will see it as spray. If necessary, try a fresh hose from the pump into a bucket of waser by the engine - with the engine running you should see the water level dropping visibly.

If it doesnt do this then the likely cause is wear in the pump or an impellor that is not rotating because the rubber vanes have become unbonded from the centre. Priose the impellor out with a screwdriver and plyers. You will have to go some to damage it.

If the pump body is worn it can be recovered by a machine shop.
 

farmer.leo

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I have now rerouted water intake thro a new hull fitting.
Re your pump belt.....this should not be nearly as tight as your alternator belt. You will get accelerated pump bearing wear by overtightening.

Does the saildrive have some benefit to having the raw water pass through it? Just wondering if re-routing to a new through hull is somehow bad for the sail drive.

I've got a saildrive too. The boat is new to me, but only 300 hours. I've taken the cover off the raw water pump and the impeller out. It looks fine.

At this point, I'm suspecting the O-Ring or it's receiving cutout. Going to have another look today at the O-ring. I feelt the O-Ring above the surface of the pump's mating face all the way around, but thinking back, it may have looked a little bit shallower on the top. My thought at the time was the rubber would squeeze itself flat, but maybe thicker O-ring would hold the cover off and thus there would be an air leak. The O-ring itself looked rounded from what I recall, and not worn. I wonder if the depression in which the O-ring sits is not right, was lower in on spot from manufacture - too low. I'm not sure what to do if that is the case. Fill with a tiny amount of permatex? If that area is the leak source, hopefully it is just the O-ring itself.
 

farmer.leo

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Are you really a farmer, Leo - farmers are in my experience very practical guys who can turn their hands to almost anything.

Anyway - you should be able to see if your pump is roitating when the engine is running and the drag on the pump isnt such as to cause belt slippage unless the belt is really slack or very ill fitting. Try turning the pump by hand with the engine stopped. If you can turn it then the belt is too slack.

If the belt is OK then check the hose from the pump to the water supply. Dont worry about the hose after that - if there is any leak there you will see it as spray. If necessary, try a fresh hose from the pump into a bucket of waser by the engine - with the engine running you should see the water level dropping visibly.

If it doesnt do this then the likely cause is wear in the pump or an impellor that is not rotating because the rubber vanes have become unbonded from the centre. Priose the impellor out with a screwdriver and plyers. You will have to go some to damage it.

If the pump body is worn it can be recovered by a machine shop.

While not really a farmer myself, I eat farm products as often as possible. :p

The alternator V-belt seemed much thicker and firmer, the raw water v-belt was thinner, perhaps looser. Is there a particular deflection amount these belts should have?

I cranked the engine for half a second with the cover off and the impeller turns OK. I can manually turn the crankshaft and the altnernator and raw water v belts turn OK. I will see if I can turn the raw water pully by hand.

On the hoses, prior tests included blowing through the raw water hoses. Hopefully photos don't make it on the internet. The raw water source through the sail drive worked OK. I could not blow from after the filter / strainer into the raw water pump while it was still assembled, which leads me to believe that the vacuum seal is good. (However, if there is an air leak in the pump itself, the impeller may have blocked this). As stated before, pouring water through a funnel down into the raw water source worked. The pump just couldn't lift from a bucket. That small section of thick black rubber pipe was air tight and visibly looks good.

Impeller is right in front of me, looks almost new. It fits in really tight, two legs are bent dramatically when they pass over the hump.

I'm hoping it's just the O-ring and a pump rebuild or replacement is not necessary.
 

KAM

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This sounds a bit worrying. My 3YM30 has only done 200 hours. It took me a long time to get it primed last month when winterising, I had to pour a lot of water into the strainer, and it certainly did not seem to be pumping as well as it should and was poor compared with my previous 30 year old Volvo which still had the original pump. My boat has only been in clean deep water. The inlet strainer has never shown any debris and the pipe runs are very short. Sounds like it may be the same problem so I will be interested in what you find.
 

NigelFortune

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Similar problems

I had a similar problem with my Lombardini raw water pump (Johnson) fitted with a Speedseal kit. I removed the face plate to change the impeller at arms length through an inspection hole. Fitted new impeller replaced face plate and tested. No water out of exhaust !! Spent next two days pulling hoses off, checking ante-syphon valve, bucket of water, hose pipe, another new impeller, eventually left after at least 8 hrs no solution. Went home had a look at Speedseal web site realised there was a bit missing. Next weekend arm through inspection hole furridge around in the bilge, low and behold missing bit. Center part is a bronze disk with PTFE washer that acts as a bearing between face plate and impeller. Refitted everything started up and worked fine. Seems gap between faceplate and impeller critical otherwise vanes on impeller cannot create water pressure in pump.
 

farmer.leo

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No Speedseal here. But just to be sure I checked the manual to make
sure there is not supposed to be a plastic bearing between the impeller and the Cover, and there isn't.

I went to the boat and the O-Ring "unfortunately" looks fine. The pulley driving the raw water pump can't be turned manually (v-belt not too loose). The raw water v-belt definitely has a little more play than the alternator. I couldn't get a decisive measurement of whether the o-ring receiving track may be deeper on the top edge, causing the o-ring to rest lower. It is almost imperceptable but I think there may be a fraction of a milimeter less o-ring exposed at the top. If the o-ring does not compress at the bottom, maybe this could be enough to let air leak and destroy the vacuum.

Assuming it's not my imagination / perception, Could a fraction of a milimeter break the vacuum and cause this problem? I have a metal ruler I could try tomorrow. I have an air compressor, I could try reassembling the pump and applying some air pressure while turning the crankshaft. Maybe I'd hear it escape out of the top of the raw water pump.

I could try making the o-ring thicker in the suspect area, or building up some sort of bedding, liquid rubber, in that spot. I know it sounds somewhat like a kludge, but there shouldn't be any motion in those parts.

The boat has what is perhaps an odd set up for the raw water intake. The strainer is slightly above the engine, making it easy to reach from the aft cabin to check and clear, but a long way to draw water. It's maybe 2.5 feet up from the sail drive, then down about 2 feet to the raw water pump. I'm now thinking that this setup absolutely needs the strainer to be primed.

Would vaseline around the O-Ring a good idea?
 

anniebray

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Does the saildrive have some benefit to having the raw water pass through it? Just wondering if re-routing to a new through hull is somehow bad for the sail drive.

I don't believe that the raw water intake thro saildrive leg has any important cooling function. In any case the outer surface of the leg has a greater surface area for that purpose. Depending on barnacle/mussel growth in your area, the saildrive water intake can also get quite congested.
Re the new thro hull water intake. This was fitted by a professional shipwright who is a fellow member of my club . The intake is a plain fitting ie without a pick up strainer, so that in the event of blockage I can "rod out" any obstruction from within the boat.The original saildrive intake is still plumbed in (with a better stop cock than the original !) so I can use either or both.
 

farmer.leo

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I would be inclined to remove the pump and strip it down on a bench.

Take note of any wear around the seals on the shaft, if there is any then this will be where air is getting in.

It looks like removing the pump is easy enough. What would I be looking for when looking at the seals, is being worn obvious?

Will I need any special tools?

Unfortunately, I didn't find a youtube on this...
 

farmer.leo

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I've read some complaints on various forums about 3YM30 water pumps, but you usually only hear from the problems so I don't know if there is definitely something "wrong". There is something wrong with my Port engine's pump.

One thing I've read is that some may have their v-belt to the raw water pump too tight, causing the bearings to have too much lateral load and thus premature pump failure. That's one thing to watch for. If you haven't had any problems, and you shouldn't at 200 hours, then you might not get any. Priming the pumps is prolly a good idea. I've been told a touch of dish soap is good to lube them.

I've still to try replacing the new pump cover which recently arrived.
 

Heckler

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I've read some complaints on various forums about 3YM30 water pumps, but you usually only hear from the problems so I don't know if there is definitely something "wrong". There is something wrong with my Port engine's pump.

One thing I've read is that some may have their v-belt to the raw water pump too tight, causing the bearings to have too much lateral load and thus premature pump failure. That's one thing to watch for. If you haven't had any problems, and you shouldn't at 200 hours, then you might not get any. Priming the pumps is prolly a good idea. I've been told a touch of dish soap is good to lube them.

I've still to try replacing the new pump cover which recently arrived.
If a pump wont prime, there is an airleak in the suction side. Thats it, full stop!
Our waterpumps wear on the cover that you take off to change the impellor. The impellors wear on the sides. If either is worn then it wont prime. The O ring on the top of the filter, the slightest imperfection will allow air in. If its a Vetus with a big wing nut in the middle, overtightening will cause the centre to contact the inside boss and then there will not be enough pressure sealing the top to the O ring. Also there is a small O ring under the washer under the wingnut.
Last but not least, the rubber impellor is moulded on to the centre metal bit that fits on the shaft. The bonding breaks, the impellor then doesnt spin at all OR!! just a bit! When it loads up to suck water it could be slipping!
Stu
 

alan17

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Water pump

I have a 3ym20. Experienced similar problems with not priming. Fitted new impeller. No joy.

Ended up fitting new b...... expensive pump. Totally solved problem. Old pump now rebuilt with new seal, impeller, resurfaced cover and bearing. Will eventually refit old/refurbished pump to see if it works.

Problem I believe could be that the cam becomes worn and cannot be re machined. Some pumps have removable and therefore renewable cams. Might try to source one such pump that will fit the 3ym20!
 
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