Substantial money saving tips for Yanmar GM Series owners

[BobnLesley]

I've posted a couple of threads recently regarding our problems with a leaking Yanmar 3GM30F seawater pump and my resolution (buying a complete new pump) has thrown-up a pricing anomaly; like all good scientific research, it was done by standing on the shoulders of those who've gone before, so a lot of the credit needs to go to Timmfive who posted this thread:
http://www.ybw.com/forums/showthrea...M30-due-to-Johnson-raw-water-pump-not-priming. :, which gave me the information to start working from

OK: So the Yanmar GM Series uses one of two seawater pumps; generally speaking, the pre 1996 engines all have a seawater pump that's numbered 128397-42500; it has its impellor secured by a pin which goes across the impellor and through into a slot in the pump's shaft; in the real world, this is a Johnson Pump numbered F4B-903-10-24509-01; this pump continued to be fitted post 1996 to 'non-EU built engines' - Let's call this one 'type A'

Post 1996 'EU built' engines used Yanmar Pump 128377-42500; this has an impeller that's secured by a woodruff key, fitted into a groove in the shaft. I have heard several suggestions (though nowhere have I found any number/reference) that these pumps were/are made for Yanmar by Jabsco? Perhaps so, perhaps not, but I can confirm that Johnson certainly manufacture a direct replacement for this pump and their reference number for it is F4B-902-10-24509-02. - Let's call this one type B.

So, money saving tip 1: If you buy the Johnson pump rather than the Yanmar one (type A or B) you will save between 40 and 60% on the like for like price. Obviously it's not quite that simple and there are distinct disadvantages with the Johnson pump: It doesn't come in an attractive polythene bag with the Yanmar logo on it, nor is it painted grey; though I guess you could rectify the latter yourself.

Money saving tip 2: It doesn't matter what age/where built your engine, you can fit either Type A or Type B, they both fit to the same two bolts and have identical pulley sizes/positions; they appear to have identical swept-volumes to the pumps, though type B has a wider edge-flange and a bigger face plate, but the bottom line is that they're interchangeable and will do an equally good job. As a guideline, using USA prices for the Johnson equivalent pumps, though having looked at a couple of UK Internet suppliers, the proportions appear to be very similar: The type B pump can be had for $220, whilst a Type A runs at around $460.

So, if you own a non-EU built post 1996 Yanmar GM engine, you can buy a new genuine Yanmar seawater pump for around US$750, alternatively or you could buy/fit the direct Johnson equivalent for US$460, or you could be a real cheap-skate and buy the Johnson equivalent for the 'E-type pump at US$220; your engine is not going to know the difference. But do please remember: You won't get a pretty Yanmar poly-bag, nor the grey painted finish.

PS: Anybody who is interested in buying some brand-new 'Type-A' (Woodruff-key) impellers or a used Speedseal face-plate for that same 'type A' pump, please send me a PM.

 

[prv]

In addition, one type of pump uses an O-ring seal while the other uses single-use paper gaskets. I can't remember which way round they are, but the O-ring version is more convenient when changing impellers so is preferable.

Pete

 

[JumbleDuck]

OK: So the Yanmar GM Series uses one of two seawater pumps; generally speaking, the pre 1996 engines all have a seawater pump that's numbered 128397-42500; it has its impellor secured by a pin which goes across the impellor and through into a slot in the pump's shaft ... Let's call this one 'type A'

Post 1996 'EU built' engines used Yanmar Pump 128377-42500; this has an impeller that's secured by a woodruff key, fitted into a groove in the shaft. ... Let's call this one type B.

The impeller on my 1GM10 is neither of these: it's driven by a flat on the shaft. Have I a Type C pump, and, if so, is it compatible with Types A and B?

 

[prv]

The impeller on my 1GM10 is neither of these: it's driven by a flat on the shaft. Have I a Type C pump, and, if so, is it compatible with Types A and B?

I suspect the OP was thinking only of the 2GM20 and 3GM30 - these are very very similar, but the 1GM10 is a little different. In particular, the bigger engines have a belt-driven water pump, but I think the 1GM10's is shaft-driven, isn't it?

Pete

 

[Birdseye]

no. the raw water pump on the 1gm10 is belt driven by a tiny belt operating on a two part pressed steel pulley. the pulley tends to split apart. the belt can be bought at way below yanmar prices from Fenner. as can the alternator belt and whats more unlike the nbits from the car spares shop they will be the correct cross section and therefore wont fill your engine bay with black rubber dust as the car ones will.

 

[rotrax]

no. the raw water pump on the 1gm10 is belt driven by a tiny belt operating on a two part pressed steel pulley. the pulley tends to split apart. the belt can be bought at way below yanmar prices from Fenner. as can the alternator belt and whats more unlike the nbits from the car spares shop they will be the correct cross section and therefore wont fill your engine bay with black rubber dust as the car ones will.

Unless the tiny belt and the two part pressed steel pulley is inside and out of sight, your description is nothing like the several 1GM10'S I have owned or serviced for others.

On the 1GM10 Yanmar engines I am familiar with, the raw water pump is to the bottom right as you kneel in front of the unit and, as a previous poster said, the impeller drive is by a flat on the shaft. The pumps are held on with small bolts and fit directly into the crankcase where the shaft is powered internally.

 

[Lakesailor]

If you want to fit an O ring instead of using gaskets it can have the face machined. I did this on a manifold I made. I had to make a jig to hold the face horizontal for the milling machine. It may be possible to clamp a water pump in the machine's vice.
Cost me a few bob to be cut by a bloke what I know.

 

[savageseadog]

The parts for the Johnson pump are available from asap although I may have got the bearings FOC from a friend in the bearing trade. Stripping the pump and replacing the bearings and seals is a relatively straightforward job.

 

[G12]

According to google, part number F4B-903-10-24509-01 (Pump type A) is for a Yanmar branded pump and is attracting Yanmar prices everywhere I look. Mine was leaking and I fixed it with a seal change but I want to carry a new seal, shaft and bearings aboard just incase but I don't want to pay Yanmar's frankly obscene prices for spares. (I thought Volvo were bad until now).

Has anyone got any info on this that I could go to a supplier in the UK with? My engine is a 2GM20 installed in 1987.

G.

 

[Leif-J]

I have a 3GM30F and want to obtain a spare raw water pump. Found this one:
http://http://www.bigbluemarine.com/pumps/yanmar-replacements/110234/110216.html
But I am quite sure it is neither Johnson or Jabsco manufactured, thus not "original", whatever that means.
Has anyone found a more original replacement made by Johnson or Jabsco - and preferably from an EU seller?

 

[Dean-Bolton]

OK: So the Yanmar GM Series uses one of two seawater pumps; generally speaking, the pre 1996 engines all have a seawater pump that's numbered 128397-42500; it has its impellor secured by a pin which goes across the impellor and through into a slot in the pump's shaft; in the real world, this is a Johnson Pump numbered F4B-903-10-24509-01; this pump continued to be fitted post 1996 to 'non-EU built engines' - Let's call this one 'type A'
Post 1996 'EU built' engines used Yanmar Pump 128377-42500; this has an impeller that's secured by a woodruff key, fitted into a groove in the shaft. I have heard several suggestions (though nowhere have I found any number/reference) that these pumps were/are made for Yanmar by Jabsco? Perhaps so, perhaps not, but I can confirm that Johnson certainly manufacture a direct replacement for this pump and their reference number for it is F4B-902-10-24509-02. - Let's call this one type B.

Hello Yanmar ‘GM’ Series engine owners. I'm a Yanmar technician.
I realise that this is an old thread but many people are using it as source of reference (I know this because I get calls about it).
I just wanted to clear up any misunderstanding about part numbers that have resulted from some errors in the OP's post. (with all due respect to the OP as this isn’t a simple thing to research)
To my knowledge there are four types of pump, each with very different characteristics, as follows:

Type:1 1980 - 1996
2GM, 2GM20, 3GM, 3GMD, 3GM20, 3GM30 (raw water cooled, fully Japanese assembled and have no 'E' in the serial number)
The Yanmar part number for the raw water pump assembly is: 728270-42002 (previous part number: 128270-42000 & 128270-42001) and it looks like this:

Note the 45 degree removable inlet and outlet elbows. It uses a gasket to seal the cover and has a replaceable wedge.
It takes impeller part number: 104211-42071 (Previously 104211-42070) that looks like this (Note the cross pin):

Type:2 1980 - 1996
2GMF, 2GM20F, 3GMF, 3GM30F (heat exchanger cooled, fully Japanese assembled and have no 'E' in the serial number)
The Yanmar part number for the raw water pump assembly is: 721575-42702 (previous part number: 721575-42701) and it looks like this:

Note the straight removable inlet and outlet connections. It uses a gasket to seal the cover and has a replaceable wedge.
It takes impeller part number: 124223-42092 (Previously 124223-42091, 124223-42090) that looks like this (Note the keyway and no cross pin):

Type:3 1996-2004
2GM20-YEU, 3GM30-YEU (raw water cooled, partly European assembled and does have an 'E' in the serial number)
The Yanmar part number for the raw water pump assembly is: 128377-42500 and it looks like this:

Note the none removable inlet and outlet connections. An ‘o’ ring is used to seal the cover and it does not a have a replaceable wedge.
It takes impeller part number: 128990-42570 (Previously 128990-42200, X08810B) that looks like this (Note the cross pin):

Type:4 1996-2004
2GM20F-YEU, 3GM30F-YEU (heat exchanger cooled, partly European assembled and does have an 'E' in the serial number)
The Yanmar part number for the raw water pump assembly is: 128397-42500 and it looks like this:

Note the none removable inlet and outlet connections. An ‘o’ ring is used to seal the cover and it does not a have a replaceable wedge.
It takes impeller part number: 128990-42570 (Previously 128990-42200, X08810B) that looks like this (Note the cross pin):

The YEU models don’t actually have ‘YEU’ on the serial number plate but instead have an ‘E’ at the beginning of the serial number.

All 4 pumps have been carefully matched to their respective engines by Yanmar. As has been mentioned previously on this forum, over-cooling or under-cooling can present if an incorrect pump is used.

I haven't mentioned 1GM, HM or YM engines as this post was getting long enough.

My apologies in advance for any mistakes made. They will be corrected when discovered.

 

[UK-WOOZY]

added post to favorites on my browser. thanks. i recently had a go at replacing my 1988 yanmar 2GM20 raw water impeller. it was a real faff having to remove the whole pump to get to the impeller and the impeller doesnt come out easily requiring many different sized sockets. ridiculous, wouldnt want to do it when needed or underway or if theres a chop. I looked at the cost of replacing the pump and was shocked at the cost. I will look at getting the johnnson some time. thanks to the OP

EDIT: thanks Dean for the explanation.

 

[Dean-Bolton]

added post to favorites on my browser. thanks. i recently had a go at replacing my 1988 yanmar 2GM20 raw water impeller. it was a real faff having to remove the whole pump to get to the impeller and the impeller doesnt come out easily requiring many different sized sockets. ridiculous, wouldnt want to do it when needed or underway or if theres a chop. I looked at the cost of replacing the pump and was shocked at the cost. I will look at getting the johnnson some time. thanks to the OP

EDIT: thanks Dean for the explanation.

Hi UK-Woozy,
I know exactly what you mean. The pump is installed with the cover plate facing towards the engine. I believe that it was done that way to make the engine more compact but it does mean that you need to remove the whole pump to remove the impeller.

The later YM series engines utilise a different bracket that allow the pump to be mounted the other way around. Like this:

This allows the impeller to be removed with the pump still attached to the engine. It might be possible to retrofit this bracket if you have enough room around the engine.
Handy tip for impeller removal: You can easily remove the impeller with a pair of water pump pliers like this:

 

[Laysula]

Hi Dean-Bolton, Do you have a part number for that bracket and does it use the original belt?
Steve

Hi UK-Woozy,
I know exactly what you mean. The pump is installed with the cover plate facing towards the engine. I believe that it was done that way to make the engine more compact but it does mean that you need to remove the whole pump to remove the impeller.

The later YM series engines utilise a different bracket that allow the pump to be mounted the other way around. Like this:

This allows the impeller to be removed with the pump still attached to the engine. It might be possible to retrofit this bracket if you have enough room around the engine.
Handy tip for impeller removal: You can easily remove the impeller with a pair of water pump pliers like this:

 

[Dean-Bolton]

Hi Steve,
I've knocked up a quick diagram with some part numbers on it.
This is how it is mounted to a YM series engine of course. I have heard of people doing the conversion on GM engines with success but I couldn't say for sure that some modification of the bracket and pipework wouldn't be required.

This is how it looks fitted to a 3YM30:

 

[NPMR]

Many years ago, I wrote to Barrus, the UK importer, regarding prices for mixer elbows imported to UK from Japan.

The summary of the complaint was that I could, via relatives in the USA, order a part (also did this for water pump for my 1GM10), that was delivered inside the US, re-directed at more cost to me in the UK, then paid import tax and VAT and it was STILL about 25% cheaper than the 'normal' price in the UK.

Barrus declined to comment on their pricing policies, but from what I saw, the same OEM prices are about 35-40% higher here in the UK than the US for exactly the same things.

Until the UK boating community get their collective act together and resist the artificially high prices, nothing is going to change.

So you either have to go all round the houses and work out 'schemes' to save a bit, or collectively have a bigger complaint to your dealers, who in turn just might get through to the importer.

We now have a 3-cylinder new Yanmar so the problem is still with us.

 

[Laysula]

Cheers Dean-Bolton.
Mines a 3gm30 f so it looks like it should be doable.
Steve

 

[UK-WOOZY]

that adaption looks ideal but i wouldnt risk buying it unless i knew for sure it would fit a 2GM20

 

[Spyro]

This will be why the gasket that comes every time I buy an impellor never fits the holes in my pump, I always end up having to cut my own.

 

[pagoda]

The parts for the Johnson pump are available from asap although I may have got the bearings FOC from a friend in the bearing trade. Stripping the pump and replacing the bearings and seals is a relatively straightforward job.

+1
I rebuilt a 3gm30 pump with new seals and bearings for <£30. Once you have the pump apart, measuring the bearings and seals is easy. I got the new bits from https://www.lancashireseals.co.uk
Just order the best S/S sealed bearings and seals with S/S garter springs and you will not need to worry about corrosion.