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34crealock 04-06-2013 10:13 AM

Yanmar 3gm raw water pump
After finally finding the raw water pump on my Yanmar, I have discovered that it is nearly impossible to get at, look at or service.Brilliant engineering. Since it is only about 2 inches from the starter motor do most folks remove the starter to change impellers or is it easier to pull the entire pump assembly off the engine to replace the impeller. Thanks. Al

Dog Ship 04-06-2013 12:04 PM

Re: Yanmar 3gm raw water pump
It is easier to pull the entire pump off.
There is an after market kit you can get that will turn the pump around so that all you have to do is take off the pumps' cover to replace the impeller. It comes with brackets and a pully that bolts right on to the exsisting holes in the block. I can't remember who makes it but maybe someone else can.

Pegasus34 04-06-2013 12:09 PM

Re: Yanmar 3gm raw water pump
I have found the only way to change the impeller is to just remove the pump. As I recall there are only a couple of bolts to remove the pump, but I don't remove the hoses. To make the change even easier, you might consider a "Speedseal". If you are not familiar with the product, it is a brass plate that replaces the the steel cover. It has fasteners you can tighten/loosen by hand, and you are much less likely to loose them in the bilge.

34crealock 04-06-2013 01:25 PM

Re: Yanmar 3gm raw water pump
Thanks for the feedback. I thought pulling the pump looked easier. Some one put knurled bolts so you can remove the pump face by hand :)but with so little space I could not get a good enough grip and once I got the bolts out I could not lever the impeller out or even see it w/o a mirror. The after market kit sounds clever. Al

Pegasus34 04-07-2013 10:29 PM

Re: Yanmar 3gm raw water pump
Al, you may already have the Speedseal, because it has knurled bolt heads. Mine has four bolts and a brass cover. You have to remove two bolts, and just loosen the other two and the cover slides off.

34crealock 04-08-2013 09:01 PM

Re: Yanmar 3gm raw water pump
Guess I don't have the speed seal since I have to remove all four bolts. I did find a tool at amazon for popping out impellers. Thanks for the help.

sailak 04-09-2013 02:50 AM

Re: Yanmar 3gm raw water pump
A guy I met had a complete spare fresh water pump. If the impeller failed he would swap out the complete pump then rebuild when he had the time. Since you pretty much have to pull the pump to get to the impeller swapping the pumps is probably faster than just replacing the impeller. The would be the added expense of the 2nd pump.

34crealock 04-09-2013 12:53 PM

Re: Yanmar 3gm raw water pump
The whole spare pump thing sounds like a good plan. I recall in the Stone Age it was quicker to swap out the entire VW beetle engine than to remove the generator. :)

Dog Ship 04-09-2013 02:59 PM

Re: Yanmar 3gm raw water pump
1 Attachment(s)
Haha, here's me about 30 odd years ago working on the Admiral's bug.

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