Yanmar raw and fresh water pumps

[ip485]

With just over 2,000 hours on the engine, well serviced and maintained, I wonder what the collective wisdom is on how long these pumps usually last and what the signs are of failure, or whether you end up just waiting until it happens! Does failure when it happens tend to be catastrophic, or does it start with leaks or other issues?

 

[RichardS]

In both cases, water leaks will usually indicate that seals are gone. This will normally be followed by bearings. The time from water being first spotted to total failure is variable but it could be up to 50 hours so. as long as regular checks are performed and water leakage is spotted early, there is usually plenty of time to sort out the issue.

As for time before repair is required, that is highly variable. Both my Yanmars have 4000 hours and none of the four pumps have had any maintenance. However, I have tried to extend their life by a) always making sure that the belts are a loose as possible commensurate with no slippage on the pulleys and b) always making sure that the coolant has a good quality and sufficiently active antifreeze present

Richard

 

[andsarkit]

My 1GM raw water pump started leaking at about 600hrs and new seals lasted another couple of years. The shaft had clear signs of wear and some pitting that looked like crevice corrosion possibly due to lack of use.
'Dinghy man' of this parish has started to make the shafts in super duplex stainless and I am hoping that it will last longer than the original.
Super duplex shaft

 

[zulloboy]

Perhaps a better approach would be to not wait, but learn how to service them yourself now. It's not a hard job, and the seals and bearings are generic types that can be bought for a fraction of the Yanmar price. As also are the impellers, although you might have to do some googling to find the correct Johnson equivalent. A vital part of the job is to clean up the shaft where the seal lip contacts it, and this can be done with using progressively finer grades of abrasive paper until you get a mirror finish.

My first try at this only lasted about 100 hours because of lack of attention to the shaft finish as described above, but the next attempt is still going strong (and dry) 700 hours later .

One huge benefit is the intimate knowledge you will gain of your cooling system, which will stand you in good stead when (not if!) you eventually have a cooling problem when you're out there.
z

 

[DinghyMan]

My 1GM raw water pump started leaking at about 600hrs and new seals lasted another couple of years. The shaft had clear signs of wear and some pitting that looked like crevice corrosion possibly due to lack of use.
'Dinghy man' of this parish has started to make the shafts in super duplex stainless and I am hoping that it will last longer than the original.
Super duplex shaft

I make shafts in both 316 Stainless and 32760 Super Duplex Stainless steel, as well as covers, gaskets, a variety of attachment methods, etc., for the 1GM10 Yanmar Water Pump

Failure is usually evident by water dripping from the hole in the bottom of the pump - onto the very expensive oil pipes that run under the engine so that hey then rust away

 

[DownWest]

Failure is usually evident by water dripping from the hole in the bottom of the pump - onto the very expensive oil pipes that run under the engine so that hey then rust away

First 1GM I looked at had a complete section of that oil pipe missing from rust. I made a simple jig to align the banjos and replaced the tube with copper. Boat had been out of use for a while and that was just one of the horrors.

 

[UK-WOOZY]

had to get a new raw water pump for my 2GM20, £600 cha ching!

 

[DinghyMan]

had to get a new raw water pump for my 2GM20, £600 cha ching!

Which bits were knackered?
Do you by any chance still have the old one?

 

[UK-WOOZY]

Which bits were knackered?
Do you by any chance still have the old one?

i do (its in the garage). it came with the boat, my fault for not getting it looked at by a surveyor. the cam and housing was worn enough that there was no suction created and i had to manually prime it by pooring water into a hose before putting it back on the seacock









new one, though thinking about replacing the engine as it has a weird loose coins sound in the background when running, may see how it goes this year. As well as the waterpump its had new Polyflex engine mounts, fuel filter on the actual engine, refurbished starter motor, new drive plate, new elbow, belts, filters, gaskets, it starts up pretty much straight away and runs well its just the noise concerns me though, the tappets have been check and are good as are the injectors-
(the in line water filter is a new addition too since i got the boat, it used to have the basket thing on the hull which i changed for a skin fitting)

 

[andyj301]

Does failure when it happens tend to be catastrophic, or does it start with leaks or other issues?

Mend your own engine sea water pump - Practical Boat Owner

 

[Halo]

As previously said it is important not to over tighten the raw water pump belt as it causes bearing failure - the pump is a wimp.

I also recommend fitting a

Honeywell Home RWD21 Water Leak Alarm

Under the engine. if the pump starts to drip this will alert you.