2 GM 20

[georgebertie]

There’s a possibility that I will need to replace the water pump.(It’s the indirectly cooled model) Genuine Yanmar pumps seem to be nearly £700 .Others much less.Is there much difference in quality? Can someone explain the vast difference in pricing? I think that I may have seen that another manufacturer (Johnson) ? make a identical..or at least interchangeable pump.Trying to get that sort of expenditure past the financial controller is going to be tough!

 

[bignick]

Assuming that you’re talking about the raw water pump, then I was in a similar situation, and decided to rebuild my old one with new bearings, seals, cam, etc.
It was a bit of a PITA getting it apart after 20+ years, but it was quite a rewarding job to do and I now know that it is running smooth as silk. Cost me about £60 plus some contributions to the swear box. I did have access to a bearing press at work though which was a considerable help.

 

[galeus]

I replaced a Jabsco raw water pump (different engine) with a Johnson years ago and it has been fine and comparable quality.

 

[Refueler]

I read somewhere that the pump was Jabsco ?

I have a 2GM20 .... not looking fwd to day it needs something.

 

[sailoppopotamus]

You say it's the "indirectly cooled" one, so presumably you mean the 2GM20F. I just replaced mine this year with a genuine Yanmar part, 350 euros new. Rebuild kit from Yanmar would've cost me around 100 euros. I chose to replace rather than rebuild as I was on holiday and didn't want to risk anything going not to plan during the rebuild. I will still rebuild the old one and keep as a spare.

As you have noticed, Yanmar do not build the pumps themselves, Johnson do. The 2GM20F shipped with various pumps made by Johnson, depending on when and where it was built. You can identify which one is on your engine from the impeller, the angle of the inlet/outlet barbs relative to the pump and whether it seals with a gasket or an oring (see the last link at the end of this post). But it doesn't really matter, you can fit either a "European" pump, or a "Japanese" pump. The former is half the price of the latter, and Yanmar dealers will typically carry both. On my engine, which was made in Japan, I found that I had a European pump, indicating that it had already been replaced in the past. I too bought a "European" pump.

So from cheapest to most expensive your options are:

1. Rebuild with an OEM rebuild kit -- just google for "2GM20F raw water pump rebuild kit".
2. Rebuild with Yanmar parts.
3. Replace the pump with a Johnson pump corresponding to one of the Yanmar pumps.
4. Replace with Yanmar 'European' pump.
5. Replace with Yanmar 'Japanese' pump.

There is no reason to go for (5), in my opinion. Options (1),(2) require you to accurately identify which pump you already have.

You can read more about this, and find part numbers, here or here.

Note: I guess that if you are switching pump types you have to be sure your current hoses can accommodate the different angles of the inlet/outlet. If not then just just replace the hoses, the hassle is definitely worth the price differential.

 

[zulloboy]

These pumps are very simple devices and easy to recondition yourself cheaply using generic seals and bearings. Mine has done over 5 years since and remains drip-free.

There other threads here and on other forums that go into the detail.