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lorenzo123 · 02-03-2012, 13:31

I suppose that's one expert's opinion about experts, altho' it sounds more like a leaky pipe.
The most problems I witnessed came from little used or unused boats; owners who don't care and pay attention to their boats deserve what they get.

Gotta agree with Island Hopper.

eyschulman · 06-03-2012, 20:05

The interval may depend on where you use your boat. If in shallows and boat is shoal you have to be more vigilant sucked up bottom wares impellars fast. At any rate a good back up is a exhaust temp. alarm SX. they are easy to install and are cheap and will save your motor from a overheat.

**Ironhorse74** · 06-03-2012, 20:44

Mine is in such a horrid place (V-drive) that I replace it every year at the dock. Way better than offshore. Still carry a spare.

**Bash** · 06-03-2012, 21:47

Quote:

Originally Posted by Don Lucas

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

I'm in the second

3 camps. I replace the impeller every other year.

By the time I've got it to the point when I can check it, I'd just as soon replace it. The impeller isn't all that expensive, and failure can be far more expensive than preventative maintenance.

Chuck Hawley · 30-07-2012, 13:22

I just replaced the impeller on my 3GM30, and it took about 20 minutes. The OEM part from Yanmar was sold in a plastic bag with no instructions, o-ring, or gasket. Since I was sold the wrong part, I discovered when the pump was apart that it's a Johnson pump from Sweden, and it takes a very conventional 810 replacement impeller. Wow, what a difference! The Johnson part comes in a clamshell box with instructions, silicone grease for installation, a gaskent AND an o-ring. Oh, it also costs about four bucks less at the boat yard store. This project also gave me an opportunity to use my new little rechargeable ratchet tool, which made removal of the bolts fast and effortless.

Final thought: the previous owner had the engine serviced about 18 months ago, and it probably has 60 hours on it since then. When I removed the old impeller, the "vanes" were starting to break off, or at least had signs of cracking. Glad I did it when I did.

**twistedtree** · 30-07-2012, 19:40

I replace my main engine and genset impellers annually in the spring, plus carry spares. If the break apart and send fragments down the water path, they can plug up heat exchangers, aftercoolers, etc. Taking those apart is a PITA, and surely not something I want to so at sea. Ditto for changing an impeller. On my main engines, I have to remove the water pumps to change the impeller - it's easier that fighting against it with poor access. To me it's cheap insurance, and increases the probability that my boating days will involve boating and not repairs.

**GordMay** · 31-07-2012, 05:43

IMO, a flexible rubber impeller should be changed annually, or every 200-250 hours of operation (whichever occurs first).

**colemj** · 31-07-2012, 14:24

I check ours about once a month or whenever I know we may be motoring a long time. We have speed seals on them and checking takes less than a minute. Changing takes 5 minutes. I replace them when I see damage like cracks in the vane roots or hardening vanes. So I guess by checking often and changing rarely, I straddle the "replace only when broke" and "replace often" camps.

Mark

cruisincanucks · 31-07-2012, 14:31

Our policy over the years has been to replace with new when you do a check and keep the removed one as a spare unless it is damaged. Seems to work as a general run for all pump style check-ups.

**Therapy** · 31-07-2012, 14:43

Quote:

Originally Posted by charliehows

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?

You use the term "reco,d"

That means reconditioned right?

If so that would include any bearings and seals (and maybe the shaft) in addition to the impeller.

Most here are talking about impeller change and not a recondition.

Rebuild is another term I use that basically means the same thing.

What do you actually mean?

lockie · 31-07-2012, 14:47

Indulge me a moment and picture this:

Capt'n A hasn't disassembled his raw water pump or changed the impeller for years. As he motors towards a strange harbour, the engine temperature alarm goes off. He looks over the side and sees there's no water coming out of the exhaust. Then he rummages around for that spare impeller he stowed 3, 4, 5 years ago. When he finally finds it he starts on the pump, a job he has only done once before some years ago(or maybe never if he's really clever), while the boat drifts.........

Cap'n B is in the same predicament, but he's done this job maybe 3, 4 5 times before, most recently less than a year ago.

Who'll fix their pump first and have the best chance of averting a major problem?

Same goes for just about every bit of kit on your boat. Learn it, blast ye!

lockie

bobconnie · 31-07-2012, 14:55

Im with Therapy on this one, reconditioned to me means impeller, wear plates and checking the face and back wear plates and machineing and respaceing clearences ect ect !! changeing an Impeller I do every 200 to 300 hours ! I do run exaust temp gauge, which will tell me if I need to change any sooner then 300 hours. just my 2 cents

**Therapy** · 31-07-2012, 14:59

Quote:

Originally Posted by lockie

Indulge me a moment and picture this:

Capt'n A hasn't disassembled his raw water pump or changed the impeller for years. As he motors towards a strange harbour, the engine temperature alarm goes off. He looks over the side and sees there's no water coming out of the exhaust. Then he rummages around for that spare impeller he stowed 3, 4, 5 years ago. When he finally finds it he starts on the pump, a job he has only done once before some years ago(or maybe never if he's really clever), while the boat drifts.........

Cap'n B is in the same predicament, but he's done this job maybe 3, 4 5 times before, most recently less than a year ago.

Who'll fix their pump first and have the best chance of averting a major problem?

Same goes for just about every bit of kit on your boat. Learn it, blast ye!

lockie

Are we talking about changing an impeller or replacing a drive shaft and seals here?

What kind of anchor does "B" have?

**Therapy** · 31-07-2012, 15:04

To add to the confusion here - the title

How Often Do You Dismantle / Check Raw Water Pump

Check is one thing.

Dismantle is something else entirely.

**GordMay** · 31-07-2012, 15:25

Quote:

Originally Posted by lockie

Indulge me a moment and picture this:
Capt'n A hasn't disassembled his raw water pump or changed the impeller for years. As he motors towards a strange harbour, the engine temperature alarm goes off. He looks over the side and sees there's no water coming out of the exhaust ..
Cap'n B is in the same predicament, but he's done this job maybe 3, 4 5 times before, most recently less than a year ago.
Who'll fix their pump first and have the best chance of averting a major problem? ...

Additionally, having recently replaced his impeller, Capt B is MUCH less likely to actually encounter this type of situation.