Hunter 49, etc impeller changing

[artboas]

Ok everyone. I'm almost there
Did a couple of "dry fits" over the winter to make sure this is going to work.
Didn't want to do it prior to launch, just in case there were problems, and I need to motor my boat from where the crane is located to my club.

So, it looks like this is going to work.
Original goal was impeller change-over in 10 minutes with no scraped nuckles, and a minimum of swearing.
Will be doing this within 3 weeks from now, and I'll post a complete write-up.
Already ran it by Hunter & Yanmar, and they all really liked it.

 

[Ralph Johnstone]

Original goal was impeller change-over in 10 minutes with no scraped nuckles, and a minimum of swearing.

Any reason for wanting to set a new speed record for an impellor change ?

I'd think that an internal inspection of the housing, cleaning the gasket faces, and coating the impellor with a water soluble lube would be far more important than speed. But then, that's just me doing it .

 

[Brezzin]

Ralph. I appreciate your thinking on this but for H49 owners changing an impeller is a project in and of itself. Last time I did mine it took about an hour and is mostly done by feel.

 

[artboas]

Any reason for wanting to set a new speed record for an impellor change ?

I'd think that an internal inspection of the housing, cleaning the gasket faces, and coating the impellor with a water soluble lube would be far more important than speed. But then, that's just me doing it .

Fair question
The real point here is that the Yanmar engines with the aft facing water pumps are almost impossible to access.
At a dock, time isn't a huge issue. But changing these impellers in a bouncing sea is downright dangerous.
On the 49 where the engine is sub-floor, the job is even more difficult.
So, this is indeed more of a safety than time issue.

 

[Ralph Johnstone]

On the 49 where the engine is sub-floor, the job is even more difficult.

Ouch ................. sounds like fun. Got any pictures of the pump location ?

If it's that bad, I would rely more on preventive maintenance and do regular inspections to avoid EVER having an impeller fail under way. Through experience, I check the impeller ever two year and check carefully for cracking at the base of the blades. My current impeller is six years old and it still got a good bill of health last year. This is a Yanmar part and not a substitution.

 

[mz4wheeler]

You could install a Sea water pump rotator kit for YANMAR, if you have space in front of your engine.

http://www.tmarin.com/rotate-and-relax.html

 

[artboas]

You could install a Sea water pump rotator kit for YANMAR, if you have space in front of your engine.

http://www.tmarin.com/rotate-and-relax.html

Well, 3 issues
That won't work for the 4JH. The water pump on the 4Jh is gear driven: not belt driven
There is absolutely no room in front of the engine in the lower area. A stringer runs across.
Lastly, I look at this solution as a little weak in implementation. Adding another pulley, and an extra belt is more complexity. With belts, tensioning is always critical.
I just don't get how Yannar designed engines with rear facing water pumps.
As you see in the video, a bouncing sea is normal conditions. How on earth can you be lying over the top of an engine performing emergency repairs?? It makes no sense.

 

[artboas]

Ouch ................. sounds like fun. Got any pictures of the pump location ?

If it's that bad, I would rely more on preventive maintenance and do regular inspections to avoid EVER having an impeller fail under way. Through experience, I check the impeller ever two year and check carefully for cracking at the base of the blades. My current impeller is six years old and it still got a good bill of health last year. This is a Yanmar part and not a substitution.

Ralph, respectfully I would LOVE to do regular inspections. But that is the whole problem; you can't. Another H49 owner I know found the only way to get at the impeller easily was to remove the intercooler. At a dock this is a huge hassle. Underway, it is impossible
This reminds me of my MGB. To change the clutch you had to pull the engine. Yuk.

 

[Ralph Johnstone]

Another H49 owner I know found the only way to get at the impeller easily was to remove the intercooler.

If you get a chance, do post a few pictures of this mechanical abortion from every possible angle. With the collective wit and insight of this group, there just MAY be a way to modify this monster. Ignoring the impeller is something that will eventually come back to bite you.

 

[Charles Erwin]

There are 4 fasteners holding the pump body to the motor. Is it possible to remove these thus to remove the entire pump in tact?

Charles

 

[mz4wheeler]

How about installing a flow meter in-line before the pump or a pressure transducer after the pump to measure/detect changes to the efficiency of pump flow?

 

[SEMPERAVANTI41]

I just purchased a 2011 Hunter 50 last December. Is the pump in the same place?

 

[artboas]

If you get a chance, do post a few pictures of this mechanical abortion from every possible angle. With the collective wit and insight of this group, there just MAY be a way to modify this monster. Ignoring the impeller is something that will eventually come back to bite you.

The water pump is under the alternator facing the rear
On the 49 /50AC the engine is mounted sub floor. It is impossible to access.
If you lie down on top of the engine using mirrors, etc, after almost 2 hours of sweat you might get it.
If you aren't at dock, this isn't possible without tearing off either the intercooler, alternator or both.
I've been working on this for awhile.
In the next 3 weeks I should have the solution tested out

 

[artboas]

There are 4 fasteners holding the pump body to the motor. Is it possible to remove these thus to remove the entire pump in tact?

Charles

Short answer is no. If you had enough space to access the mounting screws, then pulling the impeller would be a breeze.
No way to get the hoses off, and then back on again. The output hose I really short, and is obscured behind & underneath the alternator. Good idea. Too bad it won't work

 

[artboas]

How about installing a flow meter in-line before the pump or a pressure transducer after the pump to measure/detect changes to the efficiency of pump flow?

I've done this. I have an aqualarm flow detector right after the strainer. It does 2 things: it sounds an alarm. It is also wired to the engine shutoff if the water flow stops. I have a bypass switch for this.
I also have a similar flow sensor for my genset which shuts it down if the water intake is blocked.

 

[artboas]

I just purchased a 2011 Hunter 50 last December. Is the pump in the same place?

I suspect your pump is the same. Yanmar updated the engine with an accessible alternator, but only recently.
Pull your stairs & engine cover. You will know right away.
Btw, you must do the "floor modification" that I posted on the site. Without it, your engine access is very poor

 

[kloudie1]

A friend's Beneteau 43 CC has very similar problem with the same Yanmar engine. We were able to pull the pump cover plate with a small ratcheting 90 degree screwdriver (http://www.harborfreight.com/8-piece-right-angle-screwdriver-92630.html) then using a long 90 degree pliers,(http://www.harborfreight.com/16-inch-long-reach-pliers-set-38598.html) grab the impeller and by tapping the pliers rearward, we got the impeller out.. Not an easy job, and can't be done on a hot engine.
He'd bought the official Yanmar impeller puller for the engine and it did not even come close with the restricted access.
Note that on the new models of the engine, the pump faces forward and is actually accessible.

 

[Stu Jackson]

I just don't get how Yannar designed engines with rear facing water pumps.
As you see in the video, a bouncing sea is normal conditions. How on earth can you be lying over the top of an engine performing emergency repairs?? It makes no sense.

Because they are tractor engines dropped into boats by builders who didn't think it would matter to folks with 49 foot boats, thinking they'd pay to have maintenance done, instead of thinking that skippers would need to do their own maintenance. That's why!

If the engine was on a tractor, the access would be just fine!

Look, there aren't many boats out there that are perfect. But some are much better than others.

Good owners associations are really hepful to avoid having to reinvent the wheel.

This forum is great, too, but I find it unusual to find this issue being brought up for the first time here. It's gotta to have been solved before.

Have you tried a Google search? Really. I got castigated for suggesting this a year ago, but sometimes it's very helpful to expand the search beyond a single forum.

Good luck.

 

[windward54]

My 4JH3-HTE has the same issue. The access was so bad that when I bought an impeller from the local dealer, the mechanic laughed when I told him the engine. His advice was to pull the water pump and save the headaches. Turns out it was easier to pull the pump than to get to the impeller.

 

[mz4wheeler]

I've done this. I have an aqualarm flow detector right after the strainer. It does 2 things: it sounds an alarm. It is also wired to the engine shutoff if the water flow stops. I have a bypass switch for this.
I also have a similar flow sensor for my genset which shuts it down if the water intake is blocked.

Having a flow switch on the pump intake would instantly protect your engine if the flow stopped, but if one of the impeller blades busted it may not. Can you adjust the pressure settings of the flow switch?