3YM20 raw water pump

mcanderson

mcanderson

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I have a very small leak from the rear of my raw water pump and so need to get it repaired or replaced.

Has anyone ever rebuilt one of these pumps? I am pretty happy to take it off and fit a new/repaired one, but not too sure if my skills will stretch to to pulling it apart.
 
Very probably the seal needs replacing ... water drains from a weep hole so that it does not get at the bearings etc and enables early detection that it is failing

Usually a very simple job to overhaul a raw water pump. A job you should know how to do!

Inspect bearings and shaft for wear and if all is well just pop in a new seal.

Described in the YM service manual at http://www.motoren.ath.cx/menus/yanmar.php
 
The seals are replaceable as Vic says, however....

Unfortunately, Yanmar specified a pump shaft which wears very quickly.
Although spares for pumps are available at Aquafax, the shaft has a Yanmar number which they are not 'allowed' to sell you. If you are able to chat them into giving you the Johnson/Jabsco number, you can buy all the parts separately.

My 3YM30 is the same, but I have been able to get the part numbers over time and nice 'chatting' to Aquafax.
 
Not sure whether Full Circle's comment applies to Power Marine also but I have found them very helpful with Yanmar pump parts.

As Vic says, definitely a job you should be able to do and not difficult. Quite a lot of info on water pumps on my website.
 
Vyv, I had a look at you website earlier today. I was just looking for that bit more. I will look into getting the parts and trying it myself.
 
There are good videos on U-tube on how to dismantle and rebuild the pump; without needing a bearing press.
ASAP supplies were helpful and provided me with a complete list of parts required for refurbishing a Johnson F4B-903 pump as fitted to my 3YM30. You need to be sure of the model number of the pump that is fitted to your engine (it is marked on the pump cover plate);for example I believe there were two types fitted to the 3YM30 at different times.
I paid £91:94 including post (to UK address) for a pretty comprehensive list of parts (shaft, bearings, seals, cover plate etc). If you e-mail them with the Johnson pump part number they will send you the list of parts that you need.
I also just bought a complete pump from Marine Power for £294:80 (inc post to Italy), pump was £279:80; this was the best price that I could find.

It is pretty easy to refurb the pump; you can always get your local car mechanic to press on the new bearings for the cost of a pint, if you don't feel confident without a press.

Good luck,
Alan.
 
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