Hunter 49 - Impeller changing
- Thread starter Bizbat
- Start date
Hey Biz...
I would personally like to shake the hand of these Yanmar engineers that put the impellers in impossible places. I own an H376 with the 3JH2E. Even in the marina its an hour job. I had to cut out an access port in my head to be able to get into the port side of the engine. Without the access port, it would be impossible! I cannot imagine having to do this in 6' seas.
Thanks. bob
I would personally like to shake the hand of these Yanmar engineers that put the impellers in impossible places. I own an H376 with the 3JH2E. Even in the marina its an hour job. I had to cut out an access port in my head to be able to get into the port side of the engine. Without the access port, it would be impossible! I cannot imagine having to do this in 6' seas.
Thanks. bob
Looks like a great idea. My congrats to Art!
Couple of questions:
1. Instead of machining 3 new holes in the pump flange, how about only using the 3 holes with bushings? This would mean leaving 3 bolts in the crankshaft pulley alone, and only replacing the 3 bolts where the new 50mm setscrews would go.
2. On the existing pump, could just the impeller be removed and the cover plate re-installed? Of course the hoses would be removed and the hose barbs sealed.
Couple of questions:
1. Instead of machining 3 new holes in the pump flange, how about only using the 3 holes with bushings? This would mean leaving 3 bolts in the crankshaft pulley alone, and only replacing the 3 bolts where the new 50mm setscrews would go.
2. On the existing pump, could just the impeller be removed and the cover plate re-installed? Of course the hoses would be removed and the hose barbs sealed.
Ok, finally got this posted owing to the efforts of my good friend
You need to drill the holes in the pump flange. You need to have 6 bolts holding on the crankshaft pulley. The heads of the other 3 M8 bolts would be hitting the back of the pump flange. In other words, the pump has to sit flat on the crankshaft pulley. If you have the heads of 3 M8 bolts there, this isn't possible.
Getting the holes put in is not a big job by any competent machinist. I caution you to leave some tolerance in the holes, ie don't make it a +- .005 fit. When you screw in the stainless M8 studs, please appreciate they are going into a casting. So, they won't be dead straight.
Advice is to go about 1/16" tolerance.
Good question about leaving the pump.
Won't work.
At that point the pump shaft & bearings will be running dry, and they will burn out. You need water for cooling
I actually thought about pulling the impeller, and just running water through the pump. That way the pump would stay in place. The issue is that the impeller shaft would cause a lot of turbulence & obstruction as the water would try to flow through the pump body.
This upgrade works AMAZINGLY well.
When we first fired up the engine, I watched the exhaust pipe. Water literally flew out of it. Tons of volume.
I will be more than happy to answer any & all questions about this project
Good luck!
It's perfect! This is really what should have been done from the factory. I'll be ordering all the parts soon. The documentation is very good, easy to understand. Thank you so much for sharing your solution with us.
Glad I could be of help. I really suggest you buy the impeller puller. It will make the job all the much easier
Art, I have already ordered the pump & SS hose adapters. Can you advise where you purchased the brass plumbing adapters and a part number?
Got them from a place called Rona hardware.
I'll buy 3 & mail them to you. You will have to chuck them in a lathe & take the thread crests down a hair. It's still easier than machining them from scratch. Once you get the pump, just turn them to fit. 5 minute job.
Were you able to get the SS set screws?
I can also locate these for you. You also need stainless M8 nuts & lock washers
I can also locate these for you. You also need stainless M8 nuts & lock washers
Art,
Thanks for your offer, but I can easily get the parts from HD or Lowes. Did you do the lathe work yourself? By the way I just got the pump, am waiting for the parts from China.
Thanks for your offer, but I can easily get the parts from HD or Lowes. Did you do the lathe work yourself? By the way I just got the pump, am waiting for the parts from China.
The stainless set screws might be a slight challenge to get. Any full service industrial hardware place can get them.
I had a machinist do the lathe & mill work.
Incredibly capable, and it might be an option for you.
I would ask you to check that your crankshaft pulley bolt hole patterns match mine. I've seen some variance with other hunter owners.
One of the reasons I Delayed posting this was that I wanted to fully check this out, and do a complete cruise. The results were perfect.
I am still going to improve upon the anti-rotation bracket. That will come.
I wish you the best.
You will be thrilled to have a 10 minute impeller change-over
Arthur
Anyone started on this yet?
I'm interested in photos &!feedbsck
Works like s charm.
Good luck!!
Important update
At the end of last season I was still struggling with the concept of how to attach the non-rotation link to the pump.
To refresh, this is a mechanical plate (or whatever) between the pump body and the engine to prevent the pump from rotation,
Now, practically, if you secure the hoses, they will do the job owing to possible chafe.I just didn't want to do that. For fear of damaging them.
Then I cane up with a loosely fitting stripper bolt and bracket that with an oversize hole for it to float around in. (Prior photos)
This caused wear in the aluminium bracket.the system still worked 199%, but I was worried for long term.
The hole was becoming elongated from wear
The whole issue is that too many decrees of swing.
The basic problem is that the pump is linked to the engine, which moves around a bit.,
The bar which holds my present anti- rotation device is connected to the rigid boat's bilge crankcase.
There is no simple solution to this.
You are dealing with the pump floating around in all axis of direction,'which is why I had the oversized hole in the original bracket.
But this causes other problems.
When the pump starts, it lags the engine because it takes time for the friction of the blades to catch.
Then the pump rotates slightly, and the shoulder bolt hits the oversized stop hole on the bracket.
When the engine shuts down, something odd happens. The pump oscillates back & forth until the water pressure in the pump is zero. This causes the stop bolt to bang against the oversized hole, and I don't like this.
So, I finally figured out a cheap & dirty solution, which will be 100% reliable.
If you look at the engine, it rotates CW.
Therefore, the pressure on the anti-rotation bolt is also CW.
I am keeping the aluminum bar in the bottom of the engine bed, but removing the aluminum bracket with the hole in it.
I am replacing it with a medium -heavy duty compression spring with a fairly open coil pitch. This will be linked to the existing bolt which is screwed into the pump.
Here is why this works:
Most of the force is in the CW direction, which means that the spring just needs to compress. Easy enough.
But, there is also side to side, etc. vibration, which the spring will easilly deal with.
The last problem is when the pump stops, and it wants to oscillate because of the back pressure in the pump. Well this is also perfect, because the spring will go into extension mode, and keep the pump from oscillating, but not rigidly.
I'll have photos once this is done.
I'm sure all you gear heads out there understand the concept I've described in any case
Good luck!!
My solution
At the end of last season I was still struggling with the concept of how to attach the non-rotation link to the pump.
To refresh, this is a mechanical plate (or whatever) between the pump body and the engine to prevent the pump from rotation,
Now, practically, if you secure the hoses, they will do the job owing to possible chafe.I just didn't want to do that. For fear of damaging them.
Then I cane up with a loosely fitting stripper bolt and bracket that with an oversize hole for it to float around in. (Prior photos)
This caused wear in the aluminium bracket.the system still worked 199%, but I was worried for long term.
The hole was becoming elongated from wear
The whole issue is that too many decrees of swing.
The basic problem is that the pump is linked to the engine, which moves around a bit.,
The bar which holds my present anti- rotation device is connected to the rigid boat's bilge crankcase.
There is no simple solution to this.
You are dealing with the pump floating around in all axis of direction,'which is why I had the oversized hole in the original bracket.
But this causes other problems.
When the pump starts, it lags the engine because it takes time for the friction of the blades to catch.
Then the pump rotates slightly, and the shoulder bolt hits the oversized stop hole on the bracket.
When the engine shuts down, something odd happens. The pump oscillates back & forth until the water pressure in the pump is zero. This causes the stop bolt to bang against the oversized hole, and I don't like this.
So, I finally figured out a cheap & dirty solution, which will be 100% reliable.
If you look at the engine, it rotates CW.
Therefore, the pressure on the anti-rotation bolt is also CW.
I am keeping the aluminum bar in the bottom of the engine bed, but removing the aluminum bracket with the hole in it.
I am replacing it with a medium -heavy duty compression spring with a fairly open coil pitch. This will be linked to the existing bolt which is screwed into the pump.
Here is why this works:
Most of the force is in the CW direction, which means that the spring just needs to compress. Easy enough.
But, there is also side to side, etc. vibration, which the spring will easilly deal with.
The last problem is when the pump stops, and it wants to oscillate because of the back pressure in the pump. Well this is also perfect, because the spring will go into extension mode, and keep the pump from oscillating, but not rigidly.
I'll have photos once this is done.
I'm sure all you gear heads out there understand the concept I've described in any case
Good luck!!
conbdct the anti rotation part of the pouch
My solution
Art, while winterizing my boat I noticed that my pulley looks different than yours. I have not had a chance to measure the size of the holes or the thread size. Any idea what's going on?
Attachments
That is odd. If they are on the same bolt centre as my 6 bolts, then you are probably fine. I would check with Doug Dykens @ Yanmar. He knows everything
I believe my bolt centre was 82.5 mm
Just checked
It is 82.5 bolt circle on mine
Fairly certain the threads are 8mm on yours.
on my boat, i had to cut an access hole in the battery box wall to use the Jabsco 'impeller puller ' tool to get the water pump impeller out of my 3JH4E. this event of course occurred 120 miles from home on a rolling lake with an overheating engine at dusk. we had sea room and also a good anchor. we waited till morning. then i spent 2 more hours trying to find 2 of the little bitty undersized bolts that hold the cover on , which of course had fallen into the engine bilge. having extras of those little weird bolts is important because if you don't fasten the cover on with ALLLLLLL the bolts, the raw water leaks out and your engine over heats. (ask me how i know this.) then once back at the dock i had to disassemble the heat exchanger to find the pieces of impeller vane that were stuck inside the ht ex, screwing up coolant flow and making the engine run hot....of course when you t take off the ht ex end caps you lose most of the antifreeze in your system. then i had to go out to buy form a gasket because the ht ex gasket weird thin shape completely tore when i was removing it, and i did not have enough Dexcool on board to properly top off the antifreeze system....Rx: buy yourself a Speed Seal yan mar water pump cover kit . it is beautiful. (but still it wouldn't have avoided cutting a hole in the battery box...) i blame YANMAR for a stupid pump cover design. I blame the boat manufacturer for not cutting an access hole in the battery box cover in the 1st place.....