Impeller Failure

The only problem I see is that once the impeller starts to go, it will only be a matter of a few seconds before it completely deteriorates and starts to overheat. The impeller failures I have had completely destroyed the impeller and left many pieces. Any sensor for water flow or exhaust heat will only give you a very small window to start shutting things down. Bottom line, you will still have shut things down and fix the problem. So as far as I am concerned, the overheat alarm on the engine does what it needs to do. Let you know when you have a problem to shut it down and see what is wrong....ie impeller or strainer clog or whatever. I do not think you will gain anything by having a few seconds advance notice of the impeding overheat. Spend your money on more fuel to cruise 🙂

While I like the idea of a dry exhaust, I do not think that I would want to give up the room that one would occupy in a boat the size of our Tugs. Unless you pointed it out the rear (at your dinghy), you would need to run it up through the cockpit or a corner. It would be a neat item though. Probably only practical in a boat 40 foot or over.

One other thing, those folks that have had premature failures (50 hours or so), may go 500 hours on their next impeller.
 
One thing that is bothering me at this point concerns the location of impeller/pump compared with the water level line. If I'm not mistaken the pump housing on my R25's 4BY2-150 is above the water level line. This would mean (unless there's some kind of reverse flow device in the upstream section of the piping leading to the impeller/pump to stop water draining back out) if the seacock is left open any raw sea water in the line from pump to strainer will drain out. This then means the impeller is in a dry state until the engine is started again to cause the impeller to draw water into the pump housing.

When I have my seacock open I notice that the strainer bowl remains full -- but have no idea whether any water is in the line from the bowl up to the impeller/pump housing.

Even if you quickly close the seacock after shutting the engine off I don't see this to be fast enough to avoid water from draining back out from the pump housing.

I'm assuming the water enters the water pump housing at the top and the impeller forces the water downwards and into a pipe/hose leading to the heat exchanger. If this is correct then the pump housing will hold its water if the upstream water flows back to the strainer. There's still the problem of there possibly being air in the line with this though. If others can correct me on this if I have it wrong that would be appreciated. If it's correct then presumably the impeller could be running in a dry state for a few moments as the engine starts up. I understand and have read that the impeller is built to withstand running in a dry state for no longer than 40 to 60 secs. If so, then all is AOK -- but now I wonder if the premature impeller failure correlates with the number of engine startups. 😉
 
Barry,
I have a diagram of the cooling system for the 4BY2-180 and the flow is as follows: The water enters the pump from the side then goes through the hydaulic cooler, the charged air cooler, the engine heat exchanger, the exhaust mixing elbow and then the exit exhaust.
 
Well I started this discussion and it has been very interesting, but does anyone know if there an alternative to the impeller?

Would an electric water pump placed just downstream of the sea strainer work?
 
I am sure you could rig an electric pump to do the job but but they can fail too. Boats use the flex impeller pumps because they will self prime and have been proven to be reliable. If there were a better option I am sure at least one manufacture would be using it.

If you rig an electric pump, and by the way some of them use flex impellers, you need to make sure it provides enough water for cooling at full power but does not flood the system at lower engine rpm or while starting.

I have 280 hrs on my R29 with no problems. My last boat, which my Dad still owns, is a 2006 with twin Volvos, each with 780 hrs. and running the original flex impellers. Admittedly they are much easer to inspect and change. I inspect them each year and have spares but they look new. I plan to inspect the R29 when I put it back in the water in the spring, and will decide at that time if a new impeller is warranted. I already have 2 spares and may be a bit more conservative being I now have only one engine. Will probably change those Volvos for my Dad too. Seven years is enough.
 
Here's my two cents worth. Has anyone seen an Impeller Puller like the one on the following website? Bay Shore Marine is a local company here in the Chesapeake Bay, and they have a puller ($40) that their website claims is modified to work on the hard to reach Yanmar Impeller. I'm haven't purchased one (yet), but plan to when I replace my impeller.

http://bayshoremarineengines.com/impellerpuller.aspx

And no, I'm not getting a "Kick-back". :lol:
 
The problem with impeller replacement on our tugs (at least the R-27) is not the removal of the actual impeller; it is the removal of the 4 bolts and reinstallation of the bolts and belt. For the most part you are working blindly to get the bolts removed and reinserted. The belt is a stretch type belt so it has to be worked onto the pully. This is usually a two man/woman operation. Someone needs to work the belt while another turns the crankshaft with a specially made tool to fit into the crank pully area and turn it with a breaker bar.
 
Good day,

Addressing Lone Star’s tool suggestion. The handles are too long and come at a right angle to grab the impeller. With all of the comments that have been made about access to the area where the impeller is located I do not believe this tool would be of value to carry around.

The problem isn’t getting the impeller out or even back in again, that is relatively easy. The difficulty starts with getting the pulley to line up so you can get a socket on all four bolts without having to adjust for each one.
Next, remove the four bolts and don’t drop them in the bilge. The cover comes off and the belt falls off, grab that before it also goes in the bilge and take the pulley out the side.
The impeller can easily be removed with a pair of needle nose pliers. Inspect the area that the impeller came out of with your finger, searching for any sharp irregularities or groves that may have been cause by debris that got past the sea strainer and address as you see fit.. Wipe clean.
Install new impeller (after it has been lubed in extra virgin olive oil ) and turn clockwise (as you look at the front of the engine). Install O-ring and hold it in place with petroleum jelly.
Install the shaft, cover and pulley assembly.
Install the seawater pump belt. And this is where the fun begins. There is not tension adjuster, it just goes on and there is a tool to do the operation according to the Yanmar Service Manual.

Mike (Knotflying) and I attended the Mack Boring one day class in NJ last week for the 4BY2 engine. We were the only people that had enrolled and got lots of one on one with the instructor.
With an engine in the classroom we easily removed and replaced the impeller. Easily, because there was no boat around the engine. We decided to put a blanket on the top, lay over the front and change it again, with a blindfold on. The instructor was all for it but we ran out of time. Now that would have been real world repairing, because it is just about the same.

What we decided was that, with there being no bolt on the crank pulley to grab on to rotate the engine (there is a tool that fits on the pulley front in some slots) that something had to be made or purchased to do this task safely. After seeing what the belt tool looked like, that too could be fabricated or purchased.

Can we now put this puppy to bed and move onto more important issues like mounting the gas grill on the back railing and steaks?

John DeCaro
On Sallison R27

PS: I see that Mike got the first say.
 
If we are moving on to Steaks...then we have to discuss what beer would go good with the steaks?!?!?! :lol:

Being from Texas, I like Shiner Bock beer myself...any other thoughts? 😀
 
If the pump's pulley belt is slid off first then aligning the pump pulley to access the long skinny hex bolts is made very much easier. The belt can be slipped off using a flat head screw driver quite easily. I watched my R25's Yanmar 4BY2 engine technician do just this the other week and the work went smoothly and quite quickly. You do need to carefully hold onto those 4 long skinny bolts though.

It sounds like this pump access is more difficult on the R-27 vs. R25 for some reason.

The old/current impeller can be inspected/examined for cracks. missing vanes, etc using a mirror and flashlight before deciding to replace it.
 
Think about it. If you are replacing the impeller you may as well change the belt, so getting the old belt off is easy, just use a knife. The serpentine belt is behind the impeller belt. I would say it is a suckers bet not to change that at the same time. After our steaks and beers we can dedicate 4 pages to the serpentine replacement. Do you think we can we break the record for the longest thread? :lol:
 
knotflying":29kdcc1z said:
Think about it. If you are replacing the impeller you may as well change the belt, so getting the old belt off is easy, just use a knife....snip... :lol:
Click to expand...

Before cutting, make sure the new water pump's belt is the correct one/size etc... :lol:
 
I use my Ranger 25sc for fishing in open water and impeller failure scares the **** out of me. I had an overheat once while off the coast of Newport about 4 miles. I let the engine cool down loosened the strainer bolts so that upon restart water would flow into the bilge out of the strainer assembly. My notion was that any thing loose in the system might flow out. It so happened that I got lucky and this seemed to "fix" the issue. Since then I have another 300 hours on the engine and no problems with overheating. Has anyone installed this speed seal on the Yanmar 4 cylinder? If the surface it mounts against is flat and flush with the mounting surface it seems that it could easliy be made to work. I like the idea being 20 miles off the coast with a safety margin on a clogged intake.
 
nzfisher: The below was posted earlier in this topic's thread.

baz":34dnop7r said:
It looks like the Speedseal product is not compatible with the 4BY2 Yanmar engines. This is because the pump cover incorporates the pulley and impeller shaft that is held on by 4 long skinny allen key bolts -- that is, the pulley is part of the housing that gets released after the 4 bolts are removed. As this part gets removed carefully the impeller inside the pump housing remains and can be inspected using a mirror. The impeller can if necessary be carefully pulled out for its replacement.

Thus, the 'flat plate' Speedseal design would not be compatible with the 4BY2 Yanmar engine as far as I can see. This is also confirmed by my Yanmar engine service technician. Alex at Speedseal will no doubt be confirming this for me.

For the record, the Yanmar 4BY2 engine's raw water pump assembly part number is 120650-42300.

An earlier post by member Osprey also confirmed this incompatibility.
Click to expand...
 
COMMENTS APPLY TO 110 HP YANMAR

Changing the impeller on my 110 Yanmar is an ugly job. I've found the following make the job easier:

1. Ensure your impellers are threaded so that you can use the impeller removal tool that comes with the boat. Yanmar was selling impellers a few years ago without the threads and many are still out there. With the millions of parts a Yanmar dealer may have in stock, it is possible that even the dealer may be unaware of threaded and non-threaded impellers. If you have an unthreaded one installed, you'll most likely remove it with needle nose or vice grip pliers and put that one in the "spare, but used" file.

2. I found that the 4 bolts holding the impeller cover are too short for my fat and aged fingers, and I would drop the bolts (see #3). The bolt holes on the engine block are about 3/8 of an inch deep and are drilled competely through the engine support metal. There is clear air behind the hole. I purchased bolts at least a half inch longer than OEM and that made life a lot easier for me as I was better able to hold the longer bolt, better able to turn it, etc.

3. The second time I changed my impeller I made sure the bilge was clean, and then used rags to plug the space so that when I eventually dropped a bolt it would not be able to roll under the engine. The first time it was "drop the bolt, clean the bilge, fish for the bolt". The bilge under the engine should be cleaned annually anyway.

4. Inserting a new impeller is a challenge. I tried using a cable tie to compress the vanes -- ensuring all were leaning in the correct direction -- and then at least getting the impeller started into the compartment. I can't now remember if that worked, but I do remember that once it's started, a good push with the palm of my hand set it into the compartment real slick.

SpeedSeal: It seemed like such a good idea that I got one. Service and delivery good. However -- refer again to #2 -- I found the knurled bolts that come with SpeedSeal have the same thread length as the OEM bolts and therefore also too short and I never installed it, although I tried. I thought about using my aforementioned longer bolts in place of the SpeedSeal bolts but that seemed to be defeating the benefits of SpeedSeal -- all I would be doing is swapping one perfectly good cover for another perfectly good cover. If anybody wants a new, unused SpeedSeal with extra parts -- I have a deal for you! If SpeedSeal made longer knurled bolts I would consider getting some and then installing the SpeedSeal.

Dave
"Lobo"
 
Dave,
Do you think it would be possible to screw the bolts in from the "rear" of the mounting plate, creating studs? Then, you would have them to hold the cover in place while screwing nuts onto the studs. Having recently replaced the impeller on mine, I know that would be a bear, but once done it would make future R&R of the cover plate much easier. I suppose you might run the risk of cutting your fingers on said studs, though. Your thoughts?
Joe
 
Do you think it would be possible to screw the bolts in from the "rear" of the mounting plate, creating studs?
Click to expand...

great idea !!...even just one or two "studs" would be a big help.
 
While at the Seattle Boat Show, I was able to answer my own question. There were at least two vendors with the Yanmar 110 HP engine on display. As one looks forward (toward the bow), the upper left screw seems to have the most clearance for making the modification I suggested, without completely removing the water pump housing.
I did speak with a couple of individuals who told me they have removed the housing in order to replace the impeller, but those were both on boats other than Ranger Tugs. Of course, that got me to thinking about that possibility, also. (At least once, in order to set up the studs). I'm curious to know if anyone has removed the water pump housing from the 4JH4-HTE on a R-25. I'll add photos to my album.
 
On my 2009 R25 (Cummins QSD 2.0) I first lost the impellor.... replaced it.... and then the water pump c/w bearings and the belt adjuster all "blew up". All had to be replaced. It was a very expensive parts purchase. And the 2009 motor has extremely poor access to the front of the motor. I am not used to having water pump impellors as part of a regular maintenance.... but if it will save the water pump... I recommend it.
 
For those owners with the 110 HP Yanmar, it is, in fact, possible to screw the upper left (as one looks at the cover plate) machine screw in from the back-side of the pump housing. This creates a stud on which to hang the cover while starting the other screws. This one-time procedure is not easy, but well worth the effort so one does not have to hold the plate in place while simultaneously starting the screws with the fingers of one hand.
 
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