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Yamaha water impeller question...
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| dauntless-n-miami |
Posted on 05/12/14 - 8:26 AM
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Hello to all and a question, I am stumped with a raw water impeller issue.
I replaced the complete water impeller assembly, lower housing, thermostat with over-heat sensor on my 2007 Yamaha 90 two stroke roughly two month ago. After remounting the lower unit I soon started the motor using the "ear muffs" and all went well. I purchased a portable outboard water flush bag a short time after and used it about a month ago and again with good results.
Yesteday I decided to start the outboard again using the flush bag. I filled it to the appropriate level as before with a slow but steady supply of fresh water to maintain it filled (it has a 40 gallon capacity) for the sake of spillage during the run cycle.
The motor fired right up but I noticed no water flow from the "tale-tale" on the lower cowling, a bit of steam was visible. I shut the motor off after a minute and waited a bit thinking that maybe the thermostat hadn't opened. Re-started and again no flow from the "tale-tale", I let it idle for a few seconds and shut it down again and waited a bit longer for a third attempt.
On the third attempt after a few seconds of idling the "over-heat" alarm went off and I shut it down immediately. After a few minutes of cool down I connected the powerhead flush line and ran fresh water through the motor to cool it further. During this step water flowed from the "tale-tale" at a good rate. I removed the flush bag and tried with the "ear-muffs" for a final attempt. I thought to try and push water up for a result but none was achieved.
It appears the new impeller has failed and with less than a 1 hour total run time and with no salt water exposure. Any ideas what could cause a new impeller to fail so quickly and with just idle run time?
I did view very small black sediment in the flush bag which I fear may be from the impeller along with what I think are salt crystal that I have been flushing out from the powerhead since the original lowerunit removal. I thought I had flushed it out but it appears to still be present. There was a significant amount of this build up in the area of the thermostat cavity which I scraped, brushed, vaccumed, water flushed, and blew air on to remove.
Any suggestions will be greatly appreciated as I alocate time to remove the lowerunit once again for inspection.
Thanks,
Angel M.
1996 Dauntless 15, Sportsman Pkg. - 2007 Yamaha 90 HP 2-Stroke |
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| Whalerbob |
Posted on 05/12/14 - 9:18 AM
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I also have a B90 and I replaced my pump and thermostat (for the first time myself) late last season. This spring when I was checking everything out I noticed the same thing and thought the same thing as you but I replaced the thermostat first and thankfully that turned out to be the issue.
When I pulled the old thermostat I was amazed how much salt and crap was in there even though I do flush after each use. I took out the the old thermostat and blasted it with a hose and put it in a pot of water on the stove and it did function (although I'm not sure what temp it's supposed to operate). For $24 I just left the new one in there and I'm keeping the old one in my parts bag for a backup.
When I researched DIY water pump repair a big issue to watch out for is making sure the new impeller blades bend into the cup in the direction they are supposed to spin or they will burn up quickly.
Another test to confirm it is the pump is to remove the thermostat and run the engine in a tub of water with no thermostat. The engine will run cold without the thermostat but it won't hurt it, if the pump is working it will pee a full stream, if not then you either have some blockage along the line or your pump is shot.
Edited by Whalerbob on 05/12/14 - 9:41 AM |
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| dauntless-n-miami |
Posted on 05/12/14 - 9:54 AM
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Thanks Whalerbob for the reply.
I detailed in my post that the "tale-tale" or pisser functioned with a good stream when I connected the hose to the powerhead flush port. I didn't mention in the post that I used this flush port various time to better cool the block after the 3 failed attempts during start-up.
Yes, I did rotate the new impeller correctly (for the sake of the vanes) when I assembled the upper pump housing. I coated the inner stainless impeller cup and the impeller vanes with the appropriate Yamaha grease for the initial start-up 2 months ago. It has functioned twice in the last 2 months using either the "ear muffs" or the flush bag and both times it operated at idle for approximately 10 minutes with no issues.
I do remember when I installed the impeller that it fit onto it's shaft position with much effort (and yes it was aligned with the woodruff key). I inquired with a buddy with similiar Yamaha 90 regarding this fittment concern. He mentioned his impeller went on with some effort but not as difficult as mine sounded.
I am not to keen on starting the outboard with the thermostat removed, I will remove the lowerunit sometime this week and see what went wrong.
Thanks,
Angel M.
1996 Dauntless 15, Sportsman Pkg. - 2007 Yamaha 90 HP 2-Stroke |
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| Whalerbob |
Posted on 05/12/14 - 10:29 AM
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Have you tried replacing the thermostat? $24 and 5 minutes might be worth it to know and even if it's not the problem you can keep it for a spare and use it the next time.
Funny thing about running the engine without a thermostat, what prompted me to check mine in the first place is my engine was running with the symptom of "running cold" so a mechanic friend told me to check my thermostat to see if it was stuck open. Mind you this was the first time I had ever tried to replace it myself so I was confused when I popped the cap and the only thing in there was the rubber ring from the old thermostat. Upon further investigation it turns out the thermostat had completely disintegrated thus I was running for some time with no thermostat at all.
I suppose the spring is somewhere in the bowels of my engine but it's running fine the way it is so I'm not going to mess with it.
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| Phil T |
Posted on 05/12/14 - 3:43 PM
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I have never heard of a flush bag and find the idea suspect.
Running the motor on the muffs with a hose allows the proper water pressure to cool the motor.
I would proffer that the use of the bag led to insufficient water when cleaning and burned up your impeller.
If the tell tale does not flow water within 10 seconds, turn off the motor.
There are hundreds of boaters who slip their boats and only flush 2x a year.
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| dauntless-n-miami |
Posted on 05/13/14 - 6:20 AM
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Hello Phil T, the flush bags have been around for a good while now, since the mid 80's. The model I have holds 40 gallons of water and water level is just above the cavitation plate, a garden hose is still attached and keeps the bag properly filled.
Why would you think the flush bag could cause impeller failure? It only simulates the lowerunit being submerged in either ocean or fresh water. The impeller must draw water on it's own in either submerged condition. The outboard is only run at idle just like the "ear muffs".
After my initial impeller rebuild I started the outboard on the "ear muffs" and ran it for a least a good fifteen minutes but not continuously. During that period a good stream of water was present at the "tale-tale" pisser.
I used the flush bag a couple of weeks after the initial impeller break in. The "tale-tale" showed no issues then. One of the advantages to the flush bag is less exhaust noise and 2 stroke smoke. One other advantage with the bag is, one can add a bit of cleaner (degreaser, etc.) to the water mix for a thorough flush of salt contamination a least a couple of times a year.
I will know better what the failure is when the lowerunit is removed.
Thanks for the inputs...
Angel M.
1996 Dauntless 15, Sportsman Pkg. - 2007 Yamaha 90 HP 2-Stroke |
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| dauntless-n-miami |
Posted on 05/13/14 - 7:09 AM
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Here is a paragraph from a Boat US article on outboard flushing techniques. I have included the web link for all interested. For Phil T, there is a picture of a similar flush bag that I am using. I purchased the next model up which has a larger foot print so as to better accomodate my lower unit, it's actually for larger H.P. outboards so I benefit from better submergence and water capacity.
Yamaha
Yamaha gives three choices — with a flush bag, muffs, or hose-port connector Ñ and says all three methods work equally well. Bag and Muffs: Engine should be vertical, run no more than 800-900 rpm in neutral for 15 minutes with the prop removed. Be sure the engine is receiving cooling water (by checking the overboard indicator). If your outboard has more than one set of cooling inlets, a flush bag should be used. Flushing Port: Engine should not be running; it can be tilted or vertical. Prop should be removed. Flush for 10-15 minutes.
This is the way I did my Yamaha with the "ear muffs" and later with the flush bag.
The link:
http://www.boatus.com/magazine/2013/A...ht-way.asp
Hope this information helps clear some myths about flushing.
Angel M.
Edited by Phil T on 05/13/14 - 11:06 AM
1996 Dauntless 15, Sportsman Pkg. - 2007 Yamaha 90 HP 2-Stroke |
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| huckelberry145 |
Posted on 05/13/14 - 7:52 AM
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The water pump must be submerged for it to operate.
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| dauntless-n-miami |
Posted on 05/13/14 - 9:57 AM
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We are in agreement huckelberry145. My lower unit was while in the flush bag but obviously not with the "ear muffs". The lower unit removal and disassembly of the impeller housing will hopefully shed some light on the culprit.
Till then...
1996 Dauntless 15, Sportsman Pkg. - 2007 Yamaha 90 HP 2-Stroke |
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| Phil T |
Posted on 05/13/14 - 1:05 PM
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Angel -
Thanks for the information on the flush bag. One learns something new every day.
In reviewing the information and re-reading your posts, one thing popped out...
one can add a bit of cleaner (degreaser, etc.) to the water mix for a thorough flush of salt contamination a least a couple of times a year.
Why would you add degreaser to the water cooling system? I have only read about using a de-salting product such as this:
http://www.amazon.com/Salt-Away-Mixer...B003HFVOF0
While it is your choice what to use, I, personally, prefer 100% clean water via muffs.
For the overheat alarm to go off, you must have some blockage in the water channels in the head or a tube restricted. I would investigate the flexible tubing that is on the block as well as the section that feeds the nozzle in the uppercase.
The sound of my 1987 Yamaha 90 2 stroke was not too bad on the muffs. Even my neighbors 20ft away didn't mind.
I am interested to learn the results from the disassembly.
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| dauntless-n-miami |
Posted on 05/13/14 - 2:19 PM
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Hello again Phil, degreaser was just an option since I've come across a web articles where the individual or mechanic was suggesting it. They were specific in suggesting only the "Simple Green" brand and no other with a mild 10 to 1 mix ratio if it makes a difference.
I use "Salt Away" currently but the hose attachment for a motor flush is a bit of a (P.I.T.A.) at times. Added into the flush bag may be a better solution for me at least.
When I first did the disassembly a couple of months ago I discovered quite abit of salt contamination within the thermostat assembly and block cavity. I cleaned and flushed all that I could access till water drained clean from brass feed tube and exhaust manifold within the mid-section. Phil I was surprised to see a decent amount of salt crystals or sediment still coming out from the motor. The sediment was visible in the bottom of the flush bag.
While I worked on the lower unit (which took a few weeks due to a repaint) I had taken the time to spray/coat the thermostat block cavity with ample amounts of "Corrosion X" in hopes of breaking down any corrosion that was unseen further into the block water passages.
I did thoroughly water flush the penetrant/lubricant from the block prior to remounting the lower unit. There may have been some oily residue coating left but that should not have affected the impeller but, it may still be reacting with any present corrosion in the water passages. It's possible that the sediment has/had accumilated in the impeller assembly (by gravity) and tore up the impeller.
Phil what flexible hose are you refering to? I did inspect the "tale tale" hose and cowl fitting for blockage along with the block port which feeds it. To further cool down the powerhead and during each test of the impeller issue I connected the garden hose to the block flush port attachment and a strong water flow was visible at the "tale tale" pisser. I suspect the strong flow was due to the thermostat being open at temp.
I feel that there is no blockage within the powerhead assembly at this juncture. I'm hoping it's not the impeller but maybe a rubber grommet failure where the brass water feed tube connects to the top of the impeller housing.
Thanks again for the input...
Angel M.
1996 Dauntless 15, Sportsman Pkg. - 2007 Yamaha 90 HP 2-Stroke |
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| docsoma |
Posted on 05/13/14 - 9:41 PM
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The circumstance of the original post was exactly one I encountered following impeller replacement on my 1991 40hp Yamaha back in 2011.
In my case it was the feed tube being incorrectly seated or mated with the impeller housing. It is not easy to get right without a helper and a good light shining between the upper and lower units.
I think the impeller vane issue is very real.....again the whole assembly process is just fiddly enough to cause one or other vane to pop into the wrong direction.
God I wish there was a mesh like a stent to prevent a broken impeller from lodging in the upper unit potentially killing an outboard.
Finally thermostat replacement is so easy and inexpensive I wonder why one would not do it at least every other year.
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| dauntless-n-miami |
Posted on 05/14/14 - 7:17 AM
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Hello docsoma and I hope my situation is as simple as the brass feed tube and grommet misalignment. I did coat the stainless impeller cup and rubber veins well with Yamaha's higher grade marine grease in anticipation of the initial break-in.
Hopefully the impeller is not compromised. I am quite certain that the impeller veins collapsed in the correct direction during the re-assembly but, I am a firm believer in "Murphy's Law".
I will attempt removing the lower unit this evening if no thunder storms are forecasted for the Miami area yet again.
Docsoma I did replace the complete thermostat assembly with O.E.M. parts (impeller assembly as well). That included Thermostat, poppet valve and spring with rubber grommets/seals and gasket. Also I replaced the Over heat block sensor which mounts next to thermostat cover just above number 1 cylinder.
Please keep in mind that the Yamaha did start and run on two previous occassions for a minimum of 10 minutes with no apparent issues, that's what is baffeling me. The Dauntless has not been put to water yet since the rebuild.
Till the next update, thanks to all for the inputs...
Angel M.
1996 Dauntless 15, Sportsman Pkg. - 2007 Yamaha 90 HP 2-Stroke |
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| dauntless-n-miami |
Posted on 05/19/14 - 2:14 PM
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Hello W/C and an update on my impeller issue.
Pulled the lower unit off a couple of evenings ago and got into the impeller housing. Catastrophic failure of the impeller, stainless internal cup, and upper plastic housing. Impeller had only one remaining vein, the other 5 looked as if a dog had chewed them off. A definite melt-down occured, so severe that it caused the stainless cup to rotate almost 135 degrees within the upper housing which inturn caused a misalignment of the drive shaft and cup's center hole.
Remember that the impeller assembly is not concentric to the drive/input shaft. When the cup rotated the misalignment caused the edge of the center hole to rub against the shaft diameter. It put a wear ring on the shafts diameter at that location, not severe but I had to lap and polish the affected area for burrs.
I removed the thermostat cover, thermostat, and "poppet valve" with spring for further inspection. The block cavity for the thermostat was clean of any impeller debris but more salt crystals where present. I back flushed the powerhead from the thermostat area and no rubber or plastic debris was visible. Water flow through block, "tale-tale" motor flush port, and brass feed tube was excellent. I did seem to flush out a bit more of those salt crystals or sediment as with the first time and when I used the flush bag recently.
I will be ordering all new O.E.M. parts once again but I have a question. When I rebuilt the impeller assembly last I encountered some difficulty in getting the impeller to slide down the shaft and onto it's woodruff key. I had to resort to using a length of P.V.C. tubing that had the appropriate inner diameter as a drive bushing and with a moderate dead blow mallet persuade the new impeller to seat itself. From my web reviews it appears that most impeller replacements require minimal hand press force to seat the part. Can any member here with a Yamaha 90 2 stroke relate to this experience.
I am beginning to suspect that I may have originally received a defective impeller (with a smaller inner diameter)and I failed to properly seat it. The failure indicates that the new impeller was in direct contact with the stainless cup because there is barely a hint of contact on the lower stainless flat gasket that mounts atop the lower (aluminum) pump housing. I will post pictures taken during the dissassembly but any input on impeller fittment will be greatly appreciated at this point.
Thanks to all...
Angel M.
1996 Dauntless 15, Sportsman Pkg. - 2007 Yamaha 90 HP 2-Stroke |
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| dauntless-n-miami |
Posted on 05/19/14 - 3:56 PM
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Pictures of my impeller assembly damage have been uploaded to my Personal page for those that might be curious to view.
I am not planning to leave the pictures up for any length of time, this is one ordeal that I would certainly like to forget.
As I asked in my previous post, if any member here on W/C has done an impeller replacement on a Yamaha 90 2 stroke and was able to press the replacement impeller down on the input shaft with minimal or with hand press force I would appreciate hearing about it.
Thank again to all who have previously posted to my issue.
Angel M.
1996 Dauntless 15, Sportsman Pkg. - 2007 Yamaha 90 HP 2-Stroke |
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| Alan Gracewski |
Posted on 05/19/14 - 10:23 PM
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Angel, I believe you are on the right track in analyzing your pump issues. While I have not done a Yamaha water pump overhaul, I have worked on many Evinrude, Johnson, Mercury, Mariner, and Honda outboards over a 50 year period. On all those engines (plus the few inboard engines and inboard/outboard pumps), I never had to tap on the impeller over the shaft. They all had what I would call a snug sliding fit. No tool required to slide them down. Sometime, the corrosion or exhaust deposits on the drive shaft will require cleaning to bare metal to prevent the impeller from hanging up. Some fine grit emery cloth or steel wool usually is all that is required to remove these deposits. I am certain your impeller should be a sliding fit. It has to be in order to center itself between the lower wear plate and the upper/top pump housing surface. During operation, the drive shaft will move slightly due to vibration or temperature changes/thermal growth. The impeller must center itself in order to prevent the extreme binding that you experienced.
I do think that you either had a defective impeller (smaller inside diameter or out of spec) or you somehow got the wrong impeller/incorrect part. Mistakes can happen.
I would bet that with the proper impeller and the proper sliding fit on the shaft, you will have no further issues.
Al
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| tmann45 |
Posted on 05/20/14 - 7:35 AM
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dauntless-n-miami wrote:
Pictures of my impeller assembly damage have been uploaded to my Personal page for those that might be curious to view.
I am not planning to leave the pictures up for any length of time, this is one ordeal that I would certainly like to forget.
As I asked in my previous post, if any member here on W/C has done an impeller replacement on a Yamaha 90 2 stroke and was able to press the replacement impeller down on the input shaft with minimal or with hand press force I would appreciate hearing about it.
Thank again to all who have previously posted to my issue.
Angel M.
Nice pictures of an ugly situation. I really like the jig holding your lower unit, did you fabricate it?
There are a couple of master Yamaha techs giving advice at: http://www.yamahaoutboardparts.com/fo...om/forum2/
Looks like you could use some expert advice, be sure to state your engine model number.
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| dauntless-n-miami |
Posted on 05/20/14 - 7:38 AM
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Thank you Al for your input and sharing your past observations/experience. I was really beginning to second guess my mechanical abilities with this incident.
Al regarding the corrosion and exhaust contamination that can be present on the shaft and impeller area, I did thoroughly clean and polish the the entire visible length of the shaft right down to the upper gear case bearings when the lower (Aluminum) pump housing was removed.
The replacement impeller would just barely press onto it's diameter with applied hand force which I found to be very odd. I called a friend immediately with an older version of my motor who had recently done an impeller change. He recalled having to tap his into position but with no great force, nothing similar to what I was describing to him.
Al so in avoiding another similar impeller incident the next replacement should (with a light to moderate hand press) fit the input/drive shaft, correct? As I did before, lightly grease the impeller I.D., top and bottom contact area's, and it's immediate shaft area, correct? Apply a light grease film to the stainless cup and impeller vein edges for the initial first start,correct?
I just want to cover the basic's with this assembly, the remainder I can handle well.
Thank's again to all that posted...much appreciated.
Angel M.
1996 Dauntless 15, Sportsman Pkg. - 2007 Yamaha 90 HP 2-Stroke |
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| brooks89 |
Posted on 05/20/14 - 7:58 AM
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sounds too simple but are you sure you had the impeller vanes rotated into the cup in the proper direction?
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| dauntless-n-miami |
Posted on 05/20/14 - 8:02 AM
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Hello tmann45 and yes to your question.
I fabricated this fixture before removing my lower unit, it attaches to an engine stand that I have. I used the fixture during the initial disassembly and asembly, for repainting the lower unit and now again for this mishap. The fixture is very handy, it allows me to rotate the assembly 360 degree's when needed.
The fixture is modular so it should accomodate various lower unit makes and size if ever a buddy should have need of it. It's composed of steel angle with MIG'ed (right angle) members for attachment to engine stand face plate. The lower unit mounting struts are Aluminum length's with round Aluminum stand-offs for fixture clearance. One end of the Aluminum struts have machined "bolt/fastener" slots for position adjustment and better centering of the lower unit within the fixture.
Thank you for the link provided, I will certainly check out the available information and help.
Angel M.
1996 Dauntless 15, Sportsman Pkg. - 2007 Yamaha 90 HP 2-Stroke |
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