Yanma impellers

Rob_Webb

Rob_Webb

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A couple of days ago I had the same frustrating occurrence for the second year running, namely my impeller failed about a month after my annual engine service. I swapped it for the spare but it's a bloody tedious job.

It's a Yanma 3GM dating from around 1992. The water pump seems to be jabsco and the impeller fitted by my servicing agent is Volvo. The worrying thing is that the impeller itself looks like a kid's toy and in my opinion the driving mechanism (a single spindle pin through the flimsy rubber) seems a severley poor design asking for trouble (which it gives). Considering this is a mission-critical component I'm pretty unimpressed and looking for better setup. I've heard that more recent Yanmas have a bigger, better system.

Any info?
 
I had a smilar problem on my 1GM10 last year where the rubber part of the impellor unbonded from the centre shaft. Fortunately the boat was in harbour and I noticed I had no water flow when the engine started up.
Forumites advised me that Yanmar had a batch of defective impellors about 4 or 5 years ago. I replaced it (always do this every year whether it needs it or not , Yanmar quote the number of running hours in the service manual) and all is now well but it does give you food for thought. I always carry a spare and have one of those quick change covers on my water pump. However given this I would not look foraward to doing a quick impellor change whilst becalmed and drifting in a 3knot tide towards some evil looking rocks !
 
Yanmar impellers

On my two-year old Yanmar 3YM last year the impeller broke about 30 hours after replacement - original Yanmar part....
 
Simple answer to this go to ASAP supplies and replace the impellor with a "Globe" one. You need to choose a "Blue" range one. ASAP will probably be able to tell you the part number over the phone but their catalogue lists them by diameter, width and drive type. If you measure the existing one the replacement will be obvious. These little chaps are made out of a completely different class of plastic that is far more robust and unlike others will not stick to the housing and will tolerate running dry. I have changed several different engines over to this type of impellor for exactly the reasons you state with complete success.
 
4 or 5 years ago? They're kidding. It's either a design fault or they've made no attempt at all to get the faulty stock back. I have had Yanmar impellers strip throughout that period, one at the end of last season. I always carry a couple aboard my boat and have a quick change cover on the pump, like you. But doing the change with any sort of sea running is appalling (I've done it once). There's not much we can do. I am very careful to make sure water is flowing before I cast off. Not so easy to do at sea in the dark but it still needs checking.
 
I have heard that some people drill a couple of small pilot holes and screw some self tappers through the rubber to hold it on the shaft.

Just in case you are caught at sea and need to make a repair.

I have lost one so far in 4 years (2 x 1GM10 (approx 350h)). The difference between the engines is one has an above the waterline strainer and one has the strainer on the sea-cock.

The above water line is the one that failed, I wonder if those few seconds running dry as it starts caused the problems.

It would be interesting to find out the details of everyone's failures to see if there is pattern.
 
Re: Yanmar impellers

The ASAP impeller for the 1GM10 is:
Product code = 214101
Description = GLOBE BLUE IMPELLER YANMAR 1GM 6BLADE
Online Price = £12.23 +vat

I don't know if it's the same as the one fitted to your engine, probably not, but as Boatmike indicates above, they are very helpful and have a large range.
A friend of mine has got through several over the course of the last 5 years and can confirm the difficulty of changing one at sea. I haven't had any problem at all in that time but, based on his experience, always carried 2 spares, fitted a Speedseal cover and removed it during the winter when the boat was out of the water.
 
Re: Yanmar impellers

I've often wondered if the conditions here on the East Coast, with the sea like a sandy, muddy, soup exacrebate the problem. But I don't think Yanmar can expect to build pumps which are run in crystal clear waters all the time.
 
They were supposed to have gone through a bad patch, and were offering free replacements to those that failed. Think they did improve a bit after this, but not enough. Don't know if they are still offering free replacements. Worth asking.
 
Telephone this man and ask him for advice ref this:

Mr Skewes
Cellar Marine
Main Telephone: 01326 280214
Fax: 01326 280334
Porthallow
Nr Helston
Cornwall
TR126PP
 
Thanks for all the info so far. The beady-eyed amongst you will have noticed that I'm based in Auxkland so ideally I need to find a local supplier solution. SInce my original posting I gather that the newer Yanmars come with larger water pumps which in turn have much larger diameter impellers. And most importantly these impellers have a keyway-type driving mechanism as opposed to the spinlde & pin drive which seems so vulnerable.

But I also like the sound of the plastic impellers so I'll try to follow up that avenue too.

Cheers.
 
You can reduce the pain of changing your impeller by fitting a Speedseal http://www.speedseal.com/speedseal.html. I fitted mine about 3 years ago. I keep a spare impeller ready greased - it helps to keep it compressed by a cable tie - and can change it in less than a minute under way (on a 1GM10 - which is a complete b*****d with the original cover and miniature bolts)
 
Re: Yanmar impellers

Globe product seems great at avoiding impeller failure.
I found Speedseal is ok but grub screw that was covered by the pulley wheel is difficult to reach and tighten properly. so drilled two 3mm holes at rt angles thro all 3 grub screws and used a 2mm allen key to tighten. Cobalt drill bit. Still most unpleasant experience replacing impeller thro cockpit sole on my boat!
 
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