Impeller Failure

One issue that has not been addressed is what backup system can be developed if you have an impeller failure in heavy seas? Would a manually activate electric pump downstream of the sea strainer be a "get home" option?

I am going to investigate adding another sea cock and enlarging as a preventative measure.
 
trailertrawlerkismet":31625vzm said:
An impeller failure happens for various reasons, often times we never know why. An example would be a piece of plastic gets sucked up tight against the intake thru hull on the bottom of the boat therefore preventing water from entering the sea strainer.....when the engine alarm goes off or we notice the engine temperature going up and we cut the engine off and the boat is stopped the pressure is released between the thru hull and plastic and the plastic can wash away and we never knew. This could happen at any time, no matter how many hours are on our engines. When I see a piece of plastic floating around in the marina (a discarded ice bad is a good example) I try to go out of my way to get it out of the water....after all it could be my thru hull it gets sucked up against.

Something else that has not been mentioned but is very important, whether we replace the impeller or have it done, is to make sure all the broken pieces of the fins are retrieved from the impeller housing. If not this can be another cause for another impeller failure.

Jim F

...but what about all the bits of broken off vane material that have been consumed into the piping and heat exchanger ????? Can it be assumed they've all been 'passed' and shot out through the hull exhaust port ? What is the professional opinion for doing more than just removing found pieces and replacing the impeller if the old one is found with missing and/or partially missing vanes ?
 
FYI... Alex at Speedseal in UK spoke with me today and confirmed that their Speedseasl product is NOT compatible with the Yanmar 4BY2 engine.

For me, this 'seals' this discussion on the Speedseal being a product I can use on my R-25 to lessen the risk of impeller failure when running dry. 😉 🙂 Alex was sorry he could be of no help...
 
Of course, no one has mentioned here that another failure can occur when the water pump pulley belt jumps off or is too lose or even snaps/breaks.

Has anyone had this type failure ?

Must make note to myself to carry a set of spare engine belts. :lol:
 
Tuesday the engine alarm sounded about 2-3 miles from the dock and it had overheated. I called Kenny, then for a tow, and am awaiting a Yanmar person to come. It is a one week wait, and the shop is here on Shelter Island in San Diego, where I liveaboard. I am curious if this this common? There are many boats nearby; at the same time I hope this is not an indicator of how often mechanics have to be hired :?

I do not know what caused the engine to overheat, but am wondering if it may be an impeller issue. Another possibility might be a need for coolant, as I am unable to get the cover off because it is so tight.( I am going to ask a neighbor to try to loosen it so I am able to check that.)

As I read these posts, it seems that the impeller is not something that is visible or easily checked, is that correct? I am wondering if there might be a way to figure out a system to check it. I am sure better minds than mine would have figured it out by now if possible. It seems worthwhile :!:

It reminds me of the problem we have with a dinghy that is on the swim step and collects the diesel smoke/oil on the surface of the dinghy, which is not a good thing. Somehow a design change, or location change, or ? would seem worthwhile so we can check our impellers and avoid the diesel oil on our dinghies 😀

I greatly appreciate these discussions, by the way.
 
Anne: What a shame... you seem afflicted what with the prop and hull issue you had coming through the Swinomish channel last September. 🙁

Please post back what is found to be the cause for your engine high temp alert.

You mentioned "coolant"... is the level way below the full mark ? IMO its would be unusual for coolant to be low unless there's a leak somewhere. I do check mine each time before casting off and have never had to add coolant so far and engine hours are at around 245. You do have the 4BY2-150 on your R25SC, right ?

You are absolutely correct is thinking the raw water impeller is something that is not easily inspected. Just see/read many of the posts in this thread above here for evidence of this.

The only way to check the impeller is for the inside cabin step from the cockpit to be lifted or the access panel removed so that the water pump's pulley can be observed/accessed. This pulley has to be removed (remove pulley belt then remove 4 long skinny allen key bolts by aligning the pulley to access them -- and when removing these bolts be sure to take good hold of them for fear of losing them to the bilge area) along with the water pump's face plate and impeller shaft. Once this has been done the impeller will be exposed. To check the impeller if it's not obviously impaired (missing vanes, no vanes, just a bunch of pieces) a mirror can be used to take a close look at the impeller for cracks severely bent vanes etc. If this proves too difficult then you have no other recourse but to gently extract the impeller with a pair of pliers making sure not to damage the impeller's central hole that slides onto the drive shaft nor the vanes themselves. Take note of the way the impeller vanes sit as this will be useful for installing the new impeller the right way -- I don't believe the impeller rotates in either direction. That is, it's designed to rotate in a specific direction -- either clockwise or anti clockwise (others can chip in here to correct what I've said here on installing the new impeller correctly for proper rotation). When reinstalling everything make sure you follow Yanmar engine instructions for tensioning the water pump's pulley belt correctly.

This whole impeller inspection and replacement should take around 1 hour from start to finish so long as you have the right tools (you will need a flashlight) for the job and are willing to lay flat down on your belly for close to an hour.

Good luck, and again I'm really sorry to hear about your engine high temp alert issue, and be sure to post back what the cause was due to. Thanks.... -Barry
 
Anne, I would double check to make sure the seacock is open, look at the strainer to make sure it's not clogged, start the engine, and check to make sure water is pumping through the exhaust. If the exhaust doesn't have water coming out, I would bet it's the impeller. Good luck...
 
Baz, I will post when I know more. I had read your previous post about how to check the impeller, and will not be doing that. When I mentioned how I wish it were designed so we could check it, I meant something MUCH easier to access/observe.

I do not believe it is a coolant issue.

I ordinarily do not mess with the seacock because I leave it open, but I had found bits of grass-like pieces in the strainer a couple of days earlier before taking the boat to the pump out, so I closed it, cleaned out the grass then opened it. I also experienced grass coming into the toilet when pumping, (I have the manual system) so clearly grass had gotten into the water line.

Before I left the dock the seacock was open and the strainer was clear. I did notice that the splashing I check from the swim step was not as lively as usual, but there was splashing, so I did not contact anyone. Jeff, thanks for the reminders and the info about the importance of that.

I presumed that since the oil was at the right level, the strainer was clear and the transmission fluid looked fine things were ok. I did not appreciate the significance of having major splashing when the engine is started up. If it needs to be significant splashing, that is probably the issue then.

I motored slowly through the marina and out into the San Diego Bay, getting up to 5 knots. After a bit i decided to increase the speed, and did not achieve full speed. I thought I heard a beeping noise, so I slowed and stopped the engine. No noise then. I started up again, and had very little acceleration. I figured I had indeed heard a noise and it was a warning, so I turned the engine off. I did not have engine temp up on my Garmin screen, which is something I greatly regret. That was a major error on my part, along with not realizing how significant the "vigor" of the splashing is.

As I said to the Yanmar rep at the Bremerton Rendevous, I am very frustrated that I cannot read the Yanmar screen that I should also be monitoring, and in my opinion it is a major issue that there is no backlighting so it is readable. The Yanmar rep said that issue had been brought up before...
I hope the next model will be READABLE (without using a flashlight!)

The Yanmar mechanic is coming mid-morning Tuesday. Then the next step will be to find out what the insurance company says. To be continued...
 
Anne: Interesting you mentioned the weed material showing up in the head. I replaced my manual head with an electrical one and plumbed it so it uses the onboard fresh water rather than the raw water. This was done partly to avoid any evil smells generated by salt water (i.e., sulfur like smells) but also to avoid any weed-like debris getting into the head basin and interfering with the electric macerator mechanism. You've proved my point... :lol: ...so thanks.

The reference to the "major splashing in the exhaust opening" is well noted by me... thanks for posting that. 🙂 I will be paying more attention to this in the future.
 
I checked the antifreeze immediately after posting a few days back and it was fine. The mechanic is here and after all the checks water is coming in but not getting to the engine so he is now doing what we expected... Trying to get to the impeller. He did not have the square head screwdriver with him and so rather than the proverbial trip to his truck I found mine. Now he is trying to get through the white board after moving the first item under the step. So far no luck.

Before I forget, has anyone figured out a way for a secondary filter to be installed. This accessing the impeller is a real hassle and time consuming for this Yanmar mechanic.

Well, now he managed to get the board out. Yea.

I forget if another model has better engine access? This is very inconvenient! It reminds me of the photos Willie took of Herb and a mechanic in Anacortes accessing the warranty issue something or other through the step on their 27, so my guess is the problem may be the same on the 27. I am not interested in a 29 due to costs of everything, including trailering and moorage, so I guess the placement of the engine on the smaller models means poor access to the impeller.

Oops, the guy is off to his truck for a tool...I took some photos of the view of the engine which is easily visible but the impeller removal is presenting quite a challenge. He said when he came they do lots of impeller replacements...hmmm.

He is trying to remove the impeller. Eureka! Now he has to find and remove all the pieces. It is already one hour and twenty minutes from arrival at the boat. Wonder if my vacuum might help 🙂.

Now he will need to remove a hose to get to an oil cooler; guess I won't try to become a Yanmar mechanic.

On another topic, he adjusted the darkness on the Yanmar screen that gives us info on the engine. It helped quite a bit!

Another unrelated piece of information: if any of you want to winter in a mild climate in this beautiful area, I see many mechanics here every day and my wait was a week! Better pay than being a Walmart greeter no doubt 🙂

Meanwhile we do not know what blocked the intake and probably won't. If this is a somewhat common occurrence, I wonder if boat buyers put "access to impeller" on their list of things for their boats?

I know I will drive with the engine temp always visible and not depend on hearing the alarm above the engine noise!

Another expensive reminder to ALWAYS have the temp visible.

One more lesson i just learned is to purchase tow insurance even though it is already on my insurance. It seems that filing a tow claim is ok once, but insurance companies are not keen on claims, and an impeller issue is unpredictable. When I was told I could be dropped I got the message.

My Yanmar mechanic has left to go to the shop after 2 hours here for another tool since what he got from the truck earlier did not help. And it it getting close to lunch time...

Maybe being a homeowner was no more expensive :?:
 
Anne: From my point of view this mechanic you have seems a little clueless -- and I don't wish to add fuel to the fire so to speak here. On my R25 it seems fairly easy to access the impeller pulley and to remove it also. The pulley does need to be aligned to get access to 4 hex key bolts but that should not be an issue with the right hex tool and rotating the pulley once the belt has been removed. I watched my mechanic do this with ease and from start to finish replacing the impeller and using the new paper gasket that comes with the replacement should be no longer than 60 to 90 mins max. You have the R25SC so things may be a little different to what I have on my R25.

If your mechanic has replaced Yanmar 4BY2 water impellers before I would have expected he would have had all the proper tools on hand when he arrived at your boat.

It's easy for me to rant on here from afar but for you it must be stressful. I hope the mechanic does not charge you for all the time he's spending running back and forth to get tools he should have had on hand to begin with.

Replacing the impeller is not rocket science IMHO.

I do hope all gets resolved for you... and enjoy the San Diego weather... I'm told it's the best all year round.
 
The project is finally completed and the engine is running again. I watched the project as two of them worked at it in the afternoon with one having his head and shoulders underneath the step and the other working on the cockpit side as they removed the hose, gathered pieces of the old impeller and then reassembled the hose. The cockpit area is not really large enough for a good placement of an engine that is accessible. I believe that is the compromise for having the boat this size.

The manager called me up with the final bill 90 minutes later and charged me for 4 hours instead of the six hours of labor. He commented on the challenge of access. I saw that small hands and long arms would have helped.

Life has its trade-offs, just like my 25SC.
 
BaseCampAnne":wh5y4oxz said:
The project is finally completed and the engine is running again. I watched the project as two of them worked at it in the afternoon with one having his head and shoulders underneath the step and the other working on the cockpit side as they removed the hose, gathered pieces of the old impeller and then reassembled the hose. The cockpit area is not really large enough for a good placement of an engine that is accessible. I believe that is the compromise for having the boat this size.

The manager called me up with the final bill 90 minutes later and charged me for 4 hours instead of the six hours of labor. He commented on the challenge of access. I saw that small hands and long arms would have helped.

Life has its trade-offs, just like my 25SC.

Hi Anne, We are glad you got it fixed. Looks like the shop went to school on your boat. At least they were nice enough to adjust the time a bit for you. While they may have worked on a similar Yanmar engine, they obviously had not worked on it in a Ranger Tug. I wish we could learn what causes some impellers to fail with just a few hours and some last for many hours and years. I think it may have to do more with the impeller running dry than from sea grass that passed through the strainer. Even a brief period of starting up dry may cause damage that leads to failure. Transporting your boat to San Diego on a truck or trailer could have allowed this to happen. No hard data here, just an opinion. I had a failure on my 21, we kept it out of water on our lift. The impeller on this boat was easy to access and easy to change. I did notice that the new 31 has excellent access to the front of the Volvo engine. So maybe that could be the best long term solution :lol:

Enjoy your time in San Diego, I hope you get lots of cruising in this winter, a beautiful place for you. Are you planning to return to Cap Sante this spring? Have you retained your slip or do you hope to find a similar one?
 
From my observation of the sea water strainer I find it hard to believe anything 'large' can get past the strainer plate. The plate covers the complete opening and all the holes are about 1/8" diameter. That leaves very little room for anything other than very small pieces of weeds and other debris to pass through to the impeller area.

I cleaned my water strainer out the other day and the only items found in the upstream portion of the strainer were 1" to 2" pieces of thin weed swirling about above the strainer plate. Even these pieces were not able to get past the strainer plate.

When I reinstalled the plastic dome I was not sure what finishing torque I should use for tightening the dome down onto its rubber seal. I did not torque it down too much as presumably this could break/crack the plastic dome.

I'm guessing the impeller failure falls into three categories

1. Lack of sea water -- (possibly caused by blocked hull pickup, blocked input hose or even a broken/cracked strainer dome)

2. Premature failure -- Faulty/initial damage of the impeller material -- (possibly due to improper installation... impeller left in dry state for too long... dunno)

3. Age of impeller -- it simply wears itself out

It would seem to me that with all the fancy engine electronic controls we have today that a lack of raw sea water coolant could be detected via a sensor. Once this condition is sensed the engine electronic control module can shut the engine down and leave a fault code or even an understandable message on the Yanmar engine display that provides a clue as to why the engine was shut down. If this setup was designed into the engine controls it might at least lessen the impeller failures caused by running dry. A failed impeller is dire and from reports here not something that is all that rare. Just a small thought now... 😉
 
Great to hear from you Herb (and Willie.)

I really love it here, although the boating is not what I am used to throughout the Puget Sound and north through the islands. San Diego is a grand place to winter, with lots of activity on the water and things to do in the area, great weather (and for me, my son and his family) 😀

The Bay feels tiny (especially compared to the Sound) yet amazingly busy with a great variety of vessels, large and small. I am avoiding the ocean at the moment. Connecting with a few CG Aux members and starting to attend some classes will help a great deal. Meeting some other active members has already netted the possibility of a trip to Catalina on Cascadia with 2 trawlers (3 liveaboards) here in the marina in a few months.

It is good to hear that the 31' Ranger Tug has room to access the Volvo engine. I can see advantages of having a bit more space everywhere since the 25SC is my home. Learning to live small seems easier than how to solve the accessibility problem of areas of the engine. I am confident about learning how to check and replace an accessible impeller while in an ideal location in good weather, but not this impeller in a rough situation.

Lots to learn, and time and opportunity currently 😀

I look forward to returning to Cap Sante in April with more knowledge and experience.
 
Baz,

Great summation to this point. I too hope we can find a sensor or some other way to be alerted to lack of water BEFORE trashing our impeller! The temperature alarm is too late.

I plan to watch the temperature readout while hoping for a warning of no water even sooner.
 
BaseCampAnne":ec13ilvk said:
I plan to watch the temperature readout while hoping for a warning of no water even sooner.

HI Anne, It is very easy to have the temperature reading come up on most screens on your chartplotter. We do this on Willie's Tug and keep the temperature gauge as well as oil pressure on our visual scans of the plotter. Much easier than trying to see the readout on the Yanmar dim and dark readout.
 
I wonder if there is a pressure sensor that could be added to the pressure side of the raw water pump. The pressures might be kinda low because of the nature of the pump, but a zero on the reading would be a good warning of a total malfunction. Tracking the pressures could also be a good tool. A low or dropping pressure could be a signal of a of progressive failure like loosing one vane. A rising or higher than normal pressure would seem to be a signal of clogging.
 
Raw water flow alarms are available. See Aqua Alarm: https://www.aqualarm.net/

They also have overheat alarms for the exhaust as this is another symptom of loss of raw water flow, the exhaust heats up. This happen before the engine overheats.

Howard
 
There is a great solution for this problem. Eliminate the sea water pump altogether.

Some boats use a heat exchanger on the bottom of the hull and the antifreeze runs through this heat exchanger. I wish Ranger had a similar system. The down size for the boat company is it results in a dry exhaust. A dry exhaust runs hot and requires metal piping and mufflers. The wet exhaust is cool enough to allow the use of flexible rubber exhaust piping and fiberglass mufflers.
 
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