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Old 29-02-2012, 11:35   #1
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How Often Do You Dismantle / Check Raw Water Pump ?

yanmar 2qm20 - I reco,d the water pump">raw water pump about 18months ago, thinking its time to pull it out for an inspection - how often should i be looking at it?
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Old 29-02-2012, 12:27   #2
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Re: how often do you dismantle/check raw water pump?

On my boat i do a daily check on water volume when running the engine and a visual check if leak proof. On a yearly base i replace the impeller and the seals. This is usually done in spring.
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Old 29-02-2012, 12:37   #3
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Re: how often do you dismantle/check raw water pump?

there's 2 camps, the every year group and the only when it's needed group

I'm in the second
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Old 29-02-2012, 12:55   #4
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

If it aint broke dont fix it! uhhh... but have a spare! :>)
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Old 29-02-2012, 15:07   #5
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

G'day,
Just rebuilt a raw water circ pump for a customer on a 3gm yanmar 6300hrs in 14 years without ever being touched, that is the longest i have come across,it was still working perfectly without any leaks etc.On the otherhand years ago i was involed in servicing 12v71 jimmys installed in work boats working in a high silt flow river where a complete rebuild had to be done every 40-50 hrs or weekly.
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Old 29-02-2012, 15:58   #6
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

Boat was manufactured in 1995 and it's still working on the original pump impeller.
No problems at all, and the water flow is like new.
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Old 01-03-2012, 22:05   #7
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

wow 14 years/6500 hrs - i'm mostly concerned about pitting on the shaft so i might pull it for a look - but after hearing that im not too worried...thanks
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Old 01-03-2012, 22:48   #8
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

Not a bad idea to place a second screen device "after" the pump (you do have one "before" the pump, right?) just in case the impeller that you've perhaps neglected shreds. If it does, the second screen will catch it.
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Old 01-03-2012, 23:12   #9
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

Crikey, for the minimal effort and cost of an impeller replacement, versus the consequences of engine overheating causing damage &/or failure at a critical time, I can't see why even the bragging rights make it worth not doing the impeller at least annually.

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Old 01-03-2012, 23:27   #10
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

Quote:
Originally Posted by lockie View Post
Crikey, for the minimal effort and cost of an impeller replacement, versus the consequences of engine overheating causing damage &/or failure at a critical time, I can't see why even the bragging rights make it worth not doing the impeller at least annually.

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Old 01-03-2012, 23:48   #11
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

I always Ck the pump when im changing oil, look at and lube the impeller replace seals if needed, course I have wing nuts to hold the cover on LOL makes for an easy job Bob and Connie
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Old 02-03-2012, 00:03   #12
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

Quote:
Originally Posted by charliehows View Post
yanmar 2qm20 - I reco,d the raw water pump about 18months ago, thinking its time to pull it out for an inspection - how often should i be looking at it?
Yanmar is pretty good about predicting maintenance intervals. I have a 4JH3-HTE and follow the replacement recommended intervals for time and hours for all maintenance including the raw water pump impeller. In 3,000 hours and over 35,000 miles, I have never had an impeller failure. I have replaced the impeller about 6-7 times. Number of days is as important as number of hours.

Check your manual for the Yanmar recommendations.

Bill
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Old 02-03-2012, 00:09   #13
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

Depending on where you cruise your boat as shakey doug pointed out, dirty water will obviously wear the impeller and pump housing. I have a Perkins 4236 and mine lasted about 12 years before the shaft seal started to leak. The impeller was still fine.
I'm definitely in the camp if it ain't broke don't fix it camp.
There's a very useful modification you can make by fitting a 'Speedseal' replacement cover to the pump, with just 4 large knurled knobs instead of 6 fiddly little screws which always seem to drop into the bilge, coating with washing up liquid helps when fitting a new impeller eliminating the need for any special tools.
It's unecessary to complicate the system by fitting another in line filter, however
it's extremely important to backflush the raw water system with a strong water hose as any pieces of crud or broken bits of impeller will get trapped at the heat exchanger tube core and cause over heating.

Attention to the detail is the secret.
Good Luck
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Old 02-03-2012, 13:04   #14
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

If one is diligent and lucky, not changing the impeller routinely might be fine; but my guess is most boaters are more than a little like car owners; i.e., out of sight, out of mind. I've seen at least a handful of overheated engines due to old impellers in my ten plus years in the marina industry.

As for the in-line filter; if the impeller does break up, at least it will catch it. This advice has been touted by more than a few experts, and seems common sense. Also, it's easy to inspect, which also should be a routine activity. Also, a lot of engines don't have heat exhangers, so the little pieces of impeller might go even further.

The Speedseal product is a good idea.
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Old 02-03-2012, 14:12   #15
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Re: How Often Do You Dismantle / Check Raw Water Pump ?

The definition of an expert is a drip under pressure.
I can only speak of the engines of the motor cruisers and commercial barges that I've maintained and serviced. Boats used only for for short periods each year have more problems than a regularly used boat, one of these is that the impellers lose their flexibility and the vanes break off more easily.
I acknowledge that other people have a different point of view.
We all benefit from an exchange of idea's.
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