Yanmar 3GM raw water pump upgrade

[Charlie98117]

I saw some others here who used the YM series raw water pump bracket to reverse the orientation so the serviceable part is accessible without removing the pump and bracket. I did the modification to my engine and made a pdf of the process if anyone is interested in doing the same.

 

[mermike]

Nice mod, I might consider this. Completely off topic, but is that motor in your basement?

 

[Charlie98117]

Yes, I picked it up a couple years back and rebuilt at my leisure. It gets installed this week.

 

[Ralph Johnstone]

@Charlie98117 , do you know if the PN 128990-42151 bracket is suitable for reversing the water pump on a 2GM20F ?

 

[Charlie98117]

I believe so. The 2 and 3 timing cover and raw water pump are identical.

 

[Ralph Johnstone]

I only check my impellor every two or three years but I agree, it's one &^%@!*#$ of a backwards, upside down job which I can live without.

After looking at your install, this will be the next winter project once I complete the relocation of the Espar thermostat in the salon. Then I can work in comfort without frozen fingers. I can also swear better when I'm warm.

 

[Charlie98117]

The only other comment I would add is that my solution to modify the original bracket into a back bracket is a bit clunky. A cleaner and stronger attachment might be made using the YM back bracket (#23 in manual, PN 128990-42160) or fabricating something similar.

 

[Ralph Johnstone]

Will head for the boat today and after finishing up with the Espar, will start laying out a plan of attack for the bracket and see how part #23 fits into the equation.

Thanks for the heads up.

 

[Hello Below]

I only check my impellor every two or three years but I agree, it's one &^%@!*#$ of a backwards, upside down job which I can live without.

After looking at your install, this will be the next winter project once I complete the relocation of the Espar thermostat in the salon. Then I can work in comfort without frozen fingers. I can also swear better when I'm warm.

Ya gotta love it when you come across a project that you can add to your list. Alleviates the winter doldrums.

 

[kloudie1]

Posts from back in the day:
Another New Project That might be of Interest | Sailboat Owners Forums

 

[Charlie98117]

Posts from back in the day:
Another New Project That might be of Interest | Sailboat Owners Forums

Yes, Joker's thread was the guide I followed. However he mounted the new bracket on top of the old and I could not however get the alignment to work following his example, perhaps he had the other pump that came with some engines. This is why I modified the old bracket to incorporate an offset and allow the YM bracket to mount directly to the timing cover case.

 

[Ralph Johnstone]

Ya gotta love it when you come across a project that you can add to your list.

Yeah, yeah, yeah .

And if it weren't for this site, I could go back to my old hobby of hanging around pool halls, drinking beer all day, and be happy once again .

 

[mermike]

P/N 128990-42160 is $189.74 plus shipping from Toad Marine. Yikes.

 

[Charles Erwin]

This modification might not be for everyone. Frequently pump failures end up being a leaking lip seal that allows water into the bearings and the thing quits. (I have done tens of these failures.) In such a case the forward-facing version means you will have to take the whole thing off - bracket and pump - then disassemble that assembly in order to get to the bearings and the seal. Alot more work than the factory aft oriented version.

As to an impeller change just do not fiddle with trying to change the impeller with the pump on the motor - as my friend Ralph seems to favor. Instead, release two hose clamps, unscrew two bracket bolts - the bracket and the pump come off together. Change the impeller on the bench (the galley cutting board probably) and put it back in place. I bet this approach is not more than 10 minutes more (in and out) than the forward faced version impeller change. Not much since you don't change impellers but once in 250 hours' time (1000 hrs. by the manual) anyway.

Tip - I have another separate pump/bracket ready to go on short notice. Just unscrew/release the one that has quit - no matter why it quit - screw on the back up assembly and you are underway.

Charles

 

[Charlie98117]

P/N 128990-42160 is $189.74 plus shipping from Toad Marine. Yikes.

Yikes indeed. Funny it looks simple compared to the pump bracket with a welded gusset plate which is only $62 from my local Yanmar dealer. Perhaps my hack of the old bracket isn't so bad after all.

 

[Charlie98117]

I feel obligated to post an epilogue here. I now have 640 hours on the engine and the modified raw water pump mounting bracket broke off leaving my pump hanging buy the hoses. Not sure if the problem was the back bracket I fabricated or if something became loose and caused vibration but per the rule it did happen in the worst possible place, late afternoon in a narrow channel in the middle of nowhere 15 miles from the marina with 20 knots on my nose. I was able to get a tow (for $700) and have the old factory mounting bracket delivered to the marina to revert the mounting. I did like how easy it was to change the impeller the couple times I did it but I guess I'll live with the hassle of removing the pump.

 

[Ralph Johnstone]

I feel obligated to post an epilogue here.

You are the epitome of commitment to report this failure. Good on ya. Now to figure HOW it failed. Maybe the idea can be salvaged because I know that checking out that pump is one miserable SOB where it really shouldn't have to be that way.

Any chance can you supply a pic of the failed part showing where it failed ?

 

[Charlie98117]

Any chance can you supply a pic of the failed part showing where it failed ?

I was pretty angry with it and tossed it in the trash. But In this photo you can see the 2 attachment points and it broke at each one. I suspect the back bracket that I bent to create an offset had fractures from bending and probably went first. At that point the YM bracket failed too. The YM series back bracket has an extra attachment point to the engine case and would probably work just fine.

 

[Ralph Johnstone]

If understand the location of the two attachment points correctly .....................

.................. that's kind of a long lever arm to be acting on the two weld points. The raw water pump belt tension would be acting on the lever arm to produce a pretty large tension in the welds.

Won't deny it for a moment, one bitch of a location to come up with something strong enough to withstand the induced tension. And then the next question would be "can the bolt in the block withstand the stress ?"

Too stressful for me. Guess I'm stuck with the old GM way of inspecting the raw water pump.