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Boat Forum / Sailing / September 2008Yanmar YSE12 water pump - recondition or replace?
I have just replaced the seal and bearings on my Yanmar YSE12 water pump. It now pumps water and does not leak, but it doesn't seem to produce enough pressure to push water through the exhaust. The impellor is not new but looks fine. My question is, what else can I do to recondition the pump? I have tried grinding and polishing the face plate - it is fairly smooth although there is a very slight bump in the middle where the impellor has not worn it. The interior of the pump isn't perfectly smooth but neither is it seriously scored. I also had the shaft skimmed where the seal goes, to remove some scoring. Any ideas of what else I should try and if all else fails, are replacements available? TIA John. >I have just replaced the seal and bearings on my Yanmar YSE12 water pump. >It now pumps water and does not leak, but it doesn't seem to produce enough [quoted text clipped - 7 lines] >fails, are replacements available? > TIA John. The impeller may look fine, but check that the brass bush can't turn inside the blades. Alisdair > The impeller may look fine, but check that the brass bush can't turn > inside the blades. That did happen the first time around but I spotted it. The replacement impellor seems to pump OK, although I suppose it could still be slipping a bit. I'll check again. Thanks. J > I have just replaced the seal and bearings on my Yanmar YSE12 water pump. > It now pumps water and does not leak, but it doesn't seem to produce > enough pressure to push water through the exhaust. The impellor is not new > but looks fine. My question is, what else can I do to recondition the > pump? Have you considered the possibility that there is (now) nothing wrong with the pump? If the pump has been dodgy in the past, it may have let the exhaust get too hot. This could have caused the exhaust hose to delaminate internally, leading to narrowing of the bore in places, making it more difficult for water to get through. > Have you considered the possibility that there is (now) nothing wrong with > the pump? If the pump has been dodgy in the past, it may have let the > exhaust get too hot. This could have caused the exhaust hose to > delaminate > internally, leading to narrowing of the bore in places, making it more > difficult for water to get through. I don't think this happened because it failed on first start up and I always check for water coming out of the exhaust. When it failed, I switched off well before things got hot. However, I will check that the water injection point isn't somehow blocked. Not so sure how to check the exhaust hose but I'll take a look. BTW does anyone know what sort of flow the pump should produce? It pumps quite a steady stream but only with a head of about 30cm. I would have thought it might produce a fairly strong jet with no back pressure. John. >> Have you considered the possibility that there is (now) nothing wrong with >> the pump? If the pump has been dodgy in the past, it may have let the [quoted text clipped - 13 lines] > I would have >thought it might produce a fairly strong jet with no back pressure. Are the channels the water uses to flow through the engine water jacket clogged up? If you remove the thermostat, does the engine run cold?  SignatureMartin > On Wed, 3 Sep 2008 12:26:15 +0200, "John Seager" > <jseager@NOSPAMhsrc.ac.za> [quoted text clipped - 5 lines] > > If you remove the thermostat, does the engine run cold? Engine jacket is clear - I can blow through it easily enough. Showing my ignorance but I'm not sure about a thermostat, don't think it has one, it's raw water cooled. J >> On Wed, 3 Sep 2008 12:26:15 +0200, "John Seager" >> <jseager@NOSPAMhsrc.ac.za> [quoted text clipped - 7 lines] >Engine jacket is clear - I can blow through it easily enough. Showing my >ignorance but I'm not sure about a thermostat, don't think it has one, I couldn't find one in the manual Impeller part number is r04211- 4207 0 "Pump should deliver YSE 12 460 lit.,/hr. (Pump shalt speed 1900 rpm, Crankshaft speed 3000 rpm) If operated *without water, the rubbber impeller will burn)" > it's >raw water cooled. J Do you know you can download an English language version manual and a parts list from http://www.motoren.ath.cx/ 6.12 Water Cooling Failure in YSE 8 12 Manual made me smile. SignatureMartin > On Wed, 3 Sep 2008 17:15:02 +0200, "John Seager" > <jseager@NOSPAMhsrc.ac.za> [quoted text clipped - 12 lines] > > 6.12 Water Cooling Failure in YSE 8 12 Manual made me smile. Many thanks for this. The flow rate info should help me estimate whether its pumping anything like the amount of water it should. I think a new impeller sounds like a good idea too, just to be sure that it's 100% OK. J. >> On Wed, 3 Sep 2008 12:26:15 +0200, "John Seager" >> <jseager@NOSPAMhsrc.ac.za> [quoted text clipped - 8 lines] >ignorance but I'm not sure about a thermostat, don't think it has one, it's >raw water cooled. J I found this is in Yanmar Diesel Instruction Manual (5) Thermostat for cooling water is equipped as standard for better performance in cold weather. SignatureMartin > It pumps quite a steady stream but only with a head of about 30cm. Do you mean the input head needs to be 30cm for it to work at all? Or that the output head it produces is only 30cm? Neither sounds healthy. Run it with the water coming in from a bucket, i.e. disconnect the input hose from the skin fitting and dip the end into a bucket full of water. You may need to prime the hose and elevate the bucket to supply the necessary head. With the engine running, and water being sucked out of the bucket, stick your hand in the bucket and put your thumb over the end of the hose. You ought to feel a good strong suck. If not, something's wrong. There could be an air leak on the input side. With the engine off, lift the inlet hose up high and fill it up to the brim with water. Does it trickle away? If so, where does it go? If you can spot the leak on the hose itself or at the connection to the pump, you've found it. Otherwise, or if it doesn't leak away: Disconnect the pump's outlet hose. Fill the input hose, held high as before, with water. Does the water flow through the pump and emerge at the output side? You may need to blow on the input side to persuade it through. If this happens, the impeller isn't sealing properly to the back wall or faceplace. Could be because the face plate isn't on tight enough (gasket too thick) or the impeller is too small. >> It pumps quite a steady stream but only with a head of about 30cm. > [quoted text clipped - 22 lines] > the face plate isn't on tight enough (gasket too thick) or the > impeller is too small. Lots of food for thought here - thanks! 1. I meant that it only produces a head of about 30cm. I didn't expect the outflow to hit the roof but its closer to a 'trickle' than a 'gush'. 2. An air leak on the suction side seems possible - even a small one might greatly reduce the flow. The gasket is home made and reasonably thin (glossy paper and a bit of silicone) but the wear on both impellor and bore could reduce efficiency (the pump is nearly 30 years old). 3. I'll try your suggested checks to see how well it sucks and where the water goes if left alone. Thanks again. John. > I have just replaced the seal and bearings on my Yanmar YSE12 water pump. > It now pumps water and does not leak, but it doesn't seem to produce enough [quoted text clipped - 7 lines] > fails, are replacements available? > TIA John. I have a YSM8 and I have had to rebuild the water pump two years ago. I put in a new shaft, bearings and seals. I was advised to replace the body but I felt they wanted too much for it. It still leaked for another year but in this last year the seals seemed to have started to do what they are supposed to do and it has stopped leaking. I have never had a problem with exhaust water not coming out even when the pump was leaking like a sieve. I do have a relatively new u-bend at the start of the exhaust system, which I understand rusts out with raw water cooling and can block the system. Also check the tension of your water pump belt, although mine seems to run quite happily with over an inch of play in it. >I have a YSM8 and I have had to rebuild the water pump two years ago. >I put in a new shaft, bearings and seals. I was advised to replace the [quoted text clipped - 7 lines] >water pump belt, although mine seems to run quite happily with over an >inch of play in it. After various helpful posts I think I must check the pump thoroughly for leaks first. It doesn't leak water (now), but an air leak on the suction side could be just as bad, if not worse. I'll try running the outlet in a bucket to see if it's blowing bubbles. I will also check the exhaust water injection point for free flow - it is in an old and rusty swan neck and I suppose it could be blocked. John. > I have just replaced the seal and bearings on my Yanmar YSE12 water pump. > It now pumps water and does not leak, but it doesn't seem to produce enough [quoted text clipped - 7 lines] > fails, are replacements available? > TIA John. Errr excuse me, The waterpump doesn't pushes the water out of the exhaust. That is what the exhaust fumes do. The pump injects the water in the elbow of the exhaust en it gets collected in the waterlock. Then the exhaust fumes pushes the water out in blobs. Depending if you have intercooling or raw water cooling you might need to descale the intercooler or the motor in order to get a larger flow. It be blocked by deposits and than the resistance is too high for a decent flow. regards, Norbert > Errr excuse me, > The waterpump doesn't pushes the water out of the exhaust. That is what > the exhaust fumes do. > It be blocked by deposits and than the resistance > is too high for a decent flow. Thanks. You're quite correct. I guess I meant that it doesn't have enough power to push water as far as the injetion elbow, even though it pumps when the hose is disconnected. It's raw water cooled, so there isn't much to get blocked, and I can blow through tthe engine OK. I'll check for blockages at the elbow. John. >> Errr excuse me, >> The waterpump doesn't pushes the water out of the exhaust. That is what [quoted text clipped - 6 lines] >blocked, and I can blow through tthe engine OK. I'll check for blockages at >the elbow. Did you download the manual and read it's suggestions, John? SignatureMartin > Thanks. You're quite correct. I guess I meant that it doesn't have enough > power to push water as far as the injetion elbow, even though it pumps > when the hose is disconnected. It's raw water cooled, so there isn't much > to get blocked, and I can blow through tthe engine OK. I'll check for > blockages at the elbow. Here's another idea: I'm thinking back to when you said the pump only produces a 30cm head on the output. How did you measure this? By attaching a hose to its outlet with nothing on the other end, and noting that trickle stopped when you held the end up 30cm higher than the pump? If so, then what was connected to the pump's inlet at the time? The usual skin fitting? If so, could it simply be that the pump is actually situated 30cm below the waterline (you can check this by disconnecting the inlet hose from the pump, leaving it attached to the skin fitting, and seeing how far up you need to hold it before water stops pouring into the boat), and that the pump is therefore adding no pressure at all? If so, did you happen to note whether the pump still "produces" this head even when it isn't spinning, i.e. when the engine is stopped? If so, it would confirm my earlier suspicion that the pump may have an internal inlet-outlet leak, i.e. it just passes everything through. If not, are you sure the fillet is still present? That's the bit in the pump chamber which deforms the impeller vanes as they go past. If the impeller is old and tired, the vanes may not be un-deforming quickly enough once they've gone past the fillet. If a new impeller doesn't fix the problem, you could try temporarily replacing the pump cover with a bit of perspex sheet so you can see what's going on inside. Or just run it briefly with the cover off (and the seacock closed). >> Thanks. You're quite correct. I guess I meant that it doesn't have enough >> power to push water as far as the injetion elbow, even though it pumps [quoted text clipped - 17 lines] > at all? If so, did you happen to note whether the pump still "produces" > this head even when it isn't spinning, i.e. when the engine is stopped? Am I that stupid? Quite possibly, but I'm reasonably sure it was pumping not just finding its own level. I had it all set up with the engine off and the outlet hose in my hand. No water was pouring in at that stage - I would have noticed (and the crew tends to panic a bit when I allow free flow of ocean into the boat)! > If so, it would confirm my earlier suspicion that the pump may have > an internal inlet-outlet leak, i.e. it just passes everything through. [quoted text clipped - 7 lines] > on inside. Or just run it briefly with the cover off (and the seacock > closed). The fillet/cam looks fine and the impeller blades are very flexible - possibly more than I would have expected. The manual (yes, I did read it) warns you to get the impeller in the right way round, but mine doesn't seem to mind being put in wrong. The blades seem able to move back and forth depending on the direction of the rotation. I think a new impeller sound like a good idea. >>> Thanks. You're quite correct. I guess I meant that it doesn't have enough >>> power to push water as far as the injetion elbow, even though it pumps [quoted text clipped - 43 lines] >impeller >sound like a good idea. I guess you checked the oil level to make sure the water isn't finding it's way into the sump? SignatureMartin > On Wed, 10 Sep 2008 13:48:10 +0200, "John Seager" > <jseager@NOSPAMhsrc.ac.za> > wrote: >> I guess you checked the oil level to make sure the water isn't finding >> it's way > into the sump? Now there's a cheerful thought! I don't think it is, but that's one more thing to check. >> On Wed, 10 Sep 2008 13:48:10 +0200, "John Seager" >> <jseager@NOSPAMhsrc.ac.za> [quoted text clipped - 4 lines] > Now there's a cheerful thought! I don't think it is, but that's one more > thing to check. Over the years I have often heard about problems with the cooling pumps fitted to auxilliary engines in yachts. It seems astonishing these days that such an apparently simple but vital item does not appear to be designed and manufactured to be as foolproof and reliable as possible. Maybe there is good after-sales revenue for pumps exhaust bends etc. I resorted to sourcing viton seals with stainless steel for the new pump shaft I turned when I discovered the standard seals appeared to be fitted with ferrous springs. The polymer impellor is still vulnerable to dry running if there is a blockage or I forget to turn on the seacock so why isn't there some simple reservoir and recirculation from outlet to inlet to prevent dry running as found in some commercial pumps? ChrisR >> Errr excuse me, >> The waterpump doesn't pushes the water out of the exhaust. That is what [quoted text clipped - 6 lines] > blocked, and I can blow through tthe engine OK. I'll check for blockages at > the elbow. Try to check the sealing of the pump also. You mustn't be able to blow air through the pump. If that does occur you have too much play in the pump housing and you either need to replace the shaft sealing (drips water) or the cover plate of the pump (too much worn). regards, Norbert >>> Errr excuse me, >>> The waterpump doesn't pushes the water out of the exhaust. That is what [quoted text clipped - 14 lines] > regards, > Norbert I remember once in an emergency using Gasket Seal liquid sealant on my water pump cover plate. The "temporary" seal lasted 4 seasons! Dennis. >> Try to check the sealing of the pump also. You mustn't be able to blow >> air through the pump. If that does occur you have too much play in the [quoted text clipped - 3 lines] > I remember once in an emergency using Gasket Seal liquid sealant on my > water pump cover plate. The "temporary" seal lasted 4 seasons! That just ensures there is no leak between the cover plate and the pump body. What I think Norbert has in mind (as have I) with "blowing air through the pump" is that you can blow into the inlet and it comes out of the outlet, or vice versa. >>> Try to check the sealing of the pump also. You mustn't be able to blow >>> air through the pump. If that does occur you have too much play in the [quoted text clipped - 10 lines] >the pump" is that you can blow into the inlet and it comes out of the >outlet, or vice versa. One could also stick the inlet hose into a 4 litre can of water and measure how long it takes to pump it empty or even RTFM. The manual is interesting, there are greasy finger prints on all the pages where the original owner has had problems. SignatureMartin >>> Try to check the sealing of the pump also. You mustn't be able to blow >>> air through the pump. If that does occur you have too much play in the [quoted text clipped - 9 lines] > the pump" is that you can blow into the inlet and it comes out of the > outlet, or vice versa. Correct, if the gasket is blown water will come out every which way and that is easy to detect. By coincidence I worked on a hydralic pump today which had internal leakage, on the outside no leaks but hardly any hydralic pressure, turns out that the pistons were shot. regards, Norbert > Try to check the sealing of the pump also. You mustn't be able to blow air > through the pump. If that does occur you have too much play in the pump > housing and you either need to replace the shaft sealing (drips water) or > the cover plate of the pump (too much worn). Regarding the cover plate: is it supposed to be completely flat or should there be a slightly raised disc in the middle? I had assumed that the raised disc was because the rest of the plate was worn, and therefore ground it flat, but I suppose it might have been there from new. In section, mine looked like this (greatly exaggerated): _______=======________ _______________________ and is now, more or less, flat. _______________________ _______________________ > Regarding the cover plate: is it supposed to be completely flat or should > there be a slightly raised disc in the middle? I had assumed that the [quoted text clipped - 7 lines] > _______________________ > _______________________ If this was caused by wear, would you not have expected the plate to look as follows? ===_____=======_____=== _______________________ That is to say that the unworn parts would be both in the middle where there would be less rubbing from the impeller, and also around the rim where the plate mates with pump's flange? Also, in the case of wear you would expect the worn groove to be non-uniform and without sharply-defined edges. If the edges were well-defined, it suggests they were meant to be there. I don't suppose the manual is any help... What was the diameter of the raised bit? If small, it might just be to register against a recess in the impeller's hub. If larger, it might have been equal to the inside diameter of the pump body's chamber, e.g. to compensate for the thickness of any gasket. How much thickness are we talking about here? Could it be that your grinding *created* the problem of this internal leak, by making the pump chamber too wide for the impeller? Hmm. Now you'll have to buy a new impeller *and* a new plate. Might as well just buy a complete new pump. :-( >> Regarding the cover plate: is it supposed to be completely flat or should >> there be a slightly raised disc in the middle? I had assumed that the [quoted text clipped - 33 lines] >your grinding *created* the problem of this internal leak, by >making the pump chamber too wide for the impeller? In the workshop manual the cover is a normal flat disk with 6 screws holes. >Hmm. Now you'll have to buy a new impeller *and* a new plate. >Might as well just buy a complete new pump. :-( John could buy one of those impeller pump covers attached with screws with knurled heads rather than normal screws. http://www.speedseal.com/speedseal.html John note that the cover is a flat disk. SignatureMartin >>> Regarding the cover plate: is it supposed to be completely flat or should >>> there be a slightly raised disc in the middle? I had assumed that the [quoted text clipped - 44 lines] > >John note that the cover is a flat disk. I have used a Speedseal - excellent bit of kit and extremely well engineered. I suggest that you get one and try it. I am sure that grinding down the plate was a bad move. The Speedseal will replace that plate, and if you find that you need to buy a new pump then the Speedseal will still fit it, so you have not wasted any money. P.S. - used to own a boat with a YSE12 - lovely engines that go on forever. SignatureSpike >>>> Regarding the cover plate: is it supposed to be completely flat or should >>>> there be a slightly raised disc in the middle? I had assumed that the [quoted text clipped - 53 lines] >P.S. - used to own a boat with a YSE12 - lovely engines that go on >forever. The only snags with Speedseal that I know of is the cost of a replacement O ring and that a Speedseal provided to PBO years ago didn't fit. SignatureMartin >>>On Thu, 11 Sep 2008 14:20:54 GMT, Ronald Raygun >>><no.spam@localhost.localdomain> [quoted text clipped - 64 lines] > O > ring and that a Speedseal provided to PBO years ago didn't fit. It will almost certainly be an O ring of standard size which should be (very) cheaply available from any worthwhile engineers' merchant. Keith > > Try to check the sealing of the pump also. You mustn't be able to blow air > > through the pump. If that does occur you have too much play in the pump [quoted text clipped - 12 lines] > _______________________ > _______________________ The cover plate on my YSM8 is supposed to be flat, but where the impeller has been spinning it has worn the plate a tiny fraction. But the wear does not effect its ability to seal, or at least I have never had problems sealing the cover plate, my sealing problems have always been around the shaft. > Regarding the cover plate: is it supposed to be completely flat or should > there be a slightly raised disc in the middle? I had assumed that the [quoted text clipped - 8 lines] > _______________________ > _______________________ >The cover plate on my YSM8 is supposed to be flat, but where the >impeller has been spinning it has worn the plate a tiny fraction. But >the wear does not effect its ability to seal, or at least I have never >had problems sealing the cover plate, my sealing problems have always >been around the shaft. Good news! Went down to the boat yesterday and did the various tests suggested. Pump is pumping and not leaking, although probably not at full efficiency. Then I found that the elbow where the water enters the exhaust was almost completely blocked - a mixture of carbon, rust and whatever. Cleaned this out and hey presto, water coming out the exhaust again! I'm still going to put a new impeller in and will also check the thickness of the cam. John Skewes at Cellar Marine advised me that these also get worn down and reduce the efficiency. Thanks again to all the posters who have given such comprehensive insights into the workings of this simple little pump. John. >> Regarding the cover plate: is it supposed to be completely flat or should >> there be a slightly raised disc in the middle? I had assumed that the [quoted text clipped - 27 lines] >into the workings of this simple little pump. >John. I would certainly check out your (rubber) exhaust, John.. if there's been a lack of water to cool the gases (as it appears) it could most certainly have laminated. SignatureKeith replace nospam with ilf0rd >> I have just replaced the seal and bearings on my Yanmar YSE12 water >> pump. It now pumps water and does not leak, but it doesn't seem to [quoted text clipped - 5 lines] > exhaust en it gets collected in the waterlock. Then the exhaust fumes > pushes the water out in blobs. Your criticism is unjustified. Whilst it is indeed the exhaust gases which actually push the water out, the water pump must produce a greater pressure than is present in the exhaust, because otherwise water and/or exhaust gas would get pushed back into (and through) the pump. So John was quite right to say "produce enough pressure to push it through". >>> I have just replaced the seal and bearings on my Yanmar YSE12 water >>> pump. It now pumps water and does not leak, but it doesn't seem to [quoted text clipped - 10 lines] > exhaust gas would get pushed back into (and through) the pump. So John > was quite right to say "produce enough pressure to push it through". I tend to disagree. The pump must be able to withstand the pressure of the fumes, but this is a non constant pressure (pulsating). Only when the waterlock is fully loaded the pressure becomes high. At that moment the pump must prohibited the backflow of water, which is easy for a impeller pump because it is self sealing pump. The pump will still deliver some fluid in the engine block for cooling. Of course when the pump is only producing 30 cm of head, there is something seriously wrong. These kinds of pumps must be able to lift water at least a couple of meters on a open line. These are displacemnt pumps and are not very sensitive for back pressure. Either there is a blockage in the inlet, like mentioned before, or the pump has internal leaks and cannot build enough pressure to lift the water. The displacement of fluids (volume swept) of these kind of pumps is not very high regards, Norbert >I have just replaced the seal and bearings on my Yanmar YSE12 water pump. >It now pumps water and does not leak, but it doesn't seem to produce enough [quoted text clipped - 7 lines] >fails, are replacements available? > TIA John. Martin's advice to RTFM is well taken, and I have done so, plus this thread has given me loads of other ideas - thanks all. Unfortunately I haven't had time to go and check all the ideas yet. In the meantime, I've just been quoted GBP 353 (excluding carriage and VAT) for a complete new pump. It seemed like a potentially easy way out, but not at that price! I think internal leaks seems the most likely cause. I'm going to try the various blow through and pumping tests and then strip it again, fit a new impeller and see what happens. John. >>I have just replaced the seal and bearings on my Yanmar YSE12 water pump. >>It now pumps water and does not leak, but it doesn't seem to produce enough [quoted text clipped - 8 lines] >> TIA John. >Martin's advice to RTFM is well taken, I hope you appreciated the oily finger prints :o) > and I have done so, plus this thread >has given me loads of other ideas - thanks all. Unfortunately I haven't had [quoted text clipped - 4 lines] >blow through and pumping tests and then strip it again, fit a new impeller >and see what happens. Changing the impeller first seems a cheaper way to go. Before you change it, put your finger over the end of the inlet tube you should feel it sucking hard. SignatureMartin |
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