Raw water impeller replacement

[DavidComando]

This is the first commissioning I am doing on my 1986 C34 I purchased last winter. I have the M25 Universal with the 4 bolt Oberdorfer raw water pump. Upon giving my local marine supplier the part number he supplied me with the "blue rubber" replacement. When installing I was careful not to have the shaft come out. Once in there was no room for the snap ring and the 2 washers didn't sit right on th impeller. I went back to the parts dealer, he is ordering a black rubber impeller. Does it matter if the pump shaft comes forward a couple of inches to allow putting the snap ring on? Is the snap ring and washers necessary if using the blue rubber impeller? I'd like to get this worked out soon before I start putting vodka in my water tanks...then who will care?

[PAUL T.]

Dave.... I have taken the shaft completely out of the housing several times for impeller replacement, never had any problems putting it back in. Some people keep a spare shaft with impeller attached for a emergency spare. You might also check the condition of the cam to see if it needs replacing......PAUL

[Stu Jackson]

Oberdorfer Shaft

Dave

The engine manual shows that the shaft at the inside end is inset.  That design made it difficult to replace the shaft, hence, the suggestions that the shaft NOT be removed.

On our boat and others, there is a newer shaft design which has an extension at the end.  This is easy to pull out and easier to push back in.

We have a separate backup shaft with a new impeller ready to go.

I suggest you call Al and ask him if he remembers whether the shaft goes back in easily.  If it does, you have no problem.

The Universal website should have the blown up picture of the pump.  Also, a recent Tech Notes article by Ron Hill had the expanded drawing of the pump.  Use the website search engine "Oberdorfer" and you'll get to it and can access it through the Tech Notes Online.

[burner]

Have replaced mine with the original type black rubber impeller.  The only way to replace the washer and snap ring was to pull the shaft out a bit. I didn't pull it out far, it only takes a tiny bit.  It slipped right back to it's position once I finished.

[Roc]

A few years ago I went to a Yanmar Diesel seminar.  This is what the instructor said about raw water impellers.  If the impeller is inspected carefully, the vanes are moved back and forth and no cracks are noticed, you can continue to use it.  Over the winter, he suggests to remove it so the vanes don't stay bent and put it into a jar covering it with olive oil to keep it from drying out.  I have the one I used last season marinating in olive oil.  I figure I'll use it one more season.  I also keep a spare.

Roc-

[Steve S.]

Dave,  I just went through the same process with my 88 with the 4 bolt oberdorfer pump.  Went crazy trying not to pull the shaft out and put the snap ring back on.  Long story short. I ended up doing the same as Steve L.  I just pulled out the shaft a bit, put a little dishwashing soap on the shaft so the new impeller would slide on without pushing the shaft back in, and attached the snap ring.

[Stu Jackson]

OLIVE OIL

Roc

I believe it is very important for membership to know what brand of olive oil you have used.

Is it marine certified?

Did it cost twice as much as what you could get at Home Depot?

Is it "imported" or domestic?

Please, don't leave us hanging!

Thanks,

Stu

PS - does the olive oil do double duty as your head lubricant?

[Roc]

Actually I put in a little oregano, basil and a touch of garlic.  It really gives the water coming out of the exhaust a very fragrant aroma  

I think the instructor (Larry Berlin, you probably have heard of him) suggests olive oil because it is vegetable based and not petroleum based, therefore it will not harm the rubber. I don't know if any of you have taken the Yanmar seminar given by Mack Boring, but it is very informative.

[art]

Hi, all.  Just back from trying for the first time (after 2 years of ownership) to replace my impeller.  I couldn't get the darned thing off (even after removing the clip and washer) and I was afraid to yank on the blades too hard for fear of breaking one and then not being able to remove it.  Of course I was paranoid about withdrawing the shaft, given what the manual says.  Very glad to read that withdrawing the shaft is not a big deal.  Any suggestions for getting the impeller off?

Art Levine
1988 Gusty Lady

[Ted Pounds]

Ron,

Actually you can you run your engine without raw water cooling for a couple of minutes, if it's cold when you start it.  The freshwater system will absorb the heat for a bit before the temp climbs into the danger zone. I've inadvertantly ops checked this.  So in the future, if you wait till the last minute to start your engine then you can run it without raw water cooling long enough for a controlled docking.  Sort of like using alternate gear extension rather than a wheels up landing.  Just a few thoughts...

Ted :cool: