Yanmar 3GM30F – Seawater pump.

[BobnLesley]

We’re in the boondocks this week, but will shortly be heading north to the USA and our seawater pump’s started to leak from the back of the pump-body; I’m assuming that it’s the shaft’s water-seal and that once we reach the USA we could find a local Yanmar-dealer, who’ll be able to supply me with the correct seal, in a pretty box, complete with a Yanmar part-number & logo stamped onto it. I similarly suspect that said box will contain a standard lipped oil-seal, available at less than 10% of the Yanmar price, from any half-way decent Bearing-Factor.
So, to save me having to strip-down the pump before I have a new seal to rebuild it with, does anybody already know what the internal/external diameters and depth are for this seal? Or even better have the generic size/type reference number for said seal?
Thanks Bob.

 

[Robin]

We’re in the boondocks this week, but will shortly be heading north to the USA and our seawater pump’s started to leak from the back of the pump-body; I’m assuming that it’s the shaft’s water-seal and that once we reach the USA we could find a local Yanmar-dealer, who’ll be able to supply me with the correct seal, in a pretty box, complete with a Yanmar part-number & logo stamped onto it. I similarly suspect that said box will contain a standard lipped oil-seal, available at less than 10% of the Yanmar price, from any half-way decent Bearing-Factor.
So, to save me having to strip-down the pump before I have a new seal to rebuild it with, does anybody already know what the internal/external diameters and depth are for this seal? Or even better have the generic size/type reference number for said seal?
Thanks Bob.

Contact Scott Marine Power in Florida (Miami) who are Yanmar agents and you may find the genuine article And reasonably priced. They supplied me with spare impellors for Mine. If yours is a French built boat like ours and has a EU assembled Yanmar, the part number may be different too from one built in the USA Scott Marine checked the serial number of mine and ordered in the correct part which was even cheaper than the usual USA one.

 

[charles_reed]

Indeed it's the water-seal gone. I always carry a spare raw-water pump for my Yanmar, a habit developed when I had a raw-water cooled 2GM.
Once they leak, you'll need not only a water-seal, but probably a main bearing and, may-be, a shaft.
From memory the raw-water pump on those GM Yanmars was a Jabsco (now part of ITT Fluid Handling) - I've found buying spares from the OE manufacturer far, far cheaper than from a Yanmar agent. For bearings and seals I bought in Crete I was charged €5.40, the Yanmar price was just under £60. You need to make sure, purchasing generic parts (mine were SKF) that they're in stainless not conventional steel.
Shafts are a different matter - Johnson £16.40, Yanmar £163.
When I have such a problem I change raw-water pumps and re-build the faulty one at leisure - generally 800 hrs for an impeller and about 1200 for the water-seal/bearing. It's actually the bearing wear, that causes the water-seal to leak.

 

[vyv_cox]

The genuine Yanmar water pump seal has a copper-alloy spring that corrodes away, hence the leaking. There is a Volvo equivalent that has a stainless steel spring, far more long lasting. Marine Power in UK sell one with a stainless steel spring by another maker at a fraction of the price of the other two. They are fairly widely available everywhere.

When mine failed the shaft was unworn but a dodge if yours is found to be is to only partly press the seal into its housing. The lip then runs on a new point on the shaft.

 

[Robin]

I think the Euro built Yanmars had Jabsco pumps but the US ones have Johnson ones, so it is important to get the right one as US suppliers assume all Beneteaus in USA waters and all Yanmars fitted were built in the USA where in fact some like ours were French built ones (with European assembled Yanmars) When I gave Scott marine power the full engine serial number (with the E prefix) for ours they did a quick doubletake and changed the impellor type that they were originally going to supply, no problem as it took them only a few days to obtain the correct Yanmar branded and which was actually cheaper too.

 

[BobnLesley]

Thanks for the input, I'll pull it apart, check the shaft and hopefully measure/source the correct bits to put it back together. One oddity however: Whilst we have a spare water-pump, I'd been persevering with this one as I knew that the spare also leaked - we'd fitted it a few weeks previously, though only for an hour or so whilst I changed a broken impeller (that was also when the original pump began to leak). Anyway, en-route to the US we were obliged to do a lot of motoring and the leak got significantly worse (shaft knackered too now?) so we fitted the leaking 'spare' as the lesser of two evils; it leaked as expected/known, but only for an hour or so after which the leak stopped and it's subsequently been water-tight. Any opinions? All I can think of is that the bearing/seal leak stemmed from it having 'dried-out' whilst stowed in the locker and once back in service, the seal swelled and gripped the shaft again? Whatever, if I can source the correct bearings and seals, I'll get two sets and rebuild both; actually, I'll get three so we have a spare for next time too.

Thanks again, Bob.

 

[Ruffles]

When mine failed the shaft was unworn but a dodge if yours is found to be is to only partly press the seal into its housing. The lip then runs on a new point on the shaft.

You can also get double lipped seals which (hopefully!) will have the same effect.