Yanmar Impeller Change Frequency Question

[Cabo Jim]

I sometimes get an air lock in my Yanmar water pump">raw water pump when I am in big steep seas (typically at inlets) when the raw water intake is out of the water when I fly off a wave. The standard impellers run dry and are destroyed in minutes. I now use a Globe blue run dry impeller, they are twice the price but after 2 years (400 hrs.) It is in excellent condition.

[Jim Cate]

Originally Posted by Kenomac

I had to track down what turned out to be a $50 replacement impeller two years ago when disintegration was imminent. But now after starting this thread, I found Yanmar oem replacement impellers for only $19.95, so I ordered up five of them and plan on replacement every year along with the engine service.

For $20, why not? It only takes me 10-15 minutes.

Ken, do be aware that impellers and other rubber products have something of a shelf life to consider. After five years of sitting about, I'd be a bit wary of trusting the replacement.

But that is a hell of a good price! Here in Oz, impellers run >50 bucks a pop!

Jim

[sailcrazy]

My Yanmar 4JH-TE is mounted such that the impeller is in the worst possible place to access it. Guess I've been lucky, but the impeller that Yanmar mechanics put in 5 years ago is still going strong. I do carry spares, but.....if it ain't broke, don't fix it! What tool do you use to pull the old impeller out when you do change it? A needle-nose pliers?

[Dockhead]

Originally Posted by Kenomac

Do you carry a spare engine water pump onboard? I was considering the purchase of a spare at $400. My engine has 1900 hours.

No, I do not. Just impellers, drive belt, cover plate.

[sailcrazy]

Yes, I do. I carry a spare fresh water pump, as well as a replacement bearing, belts, hoses, etc for the system. I also carry salt water cooling system bits, like bearings, impellers, gaskets, etc. If you carry it.....you'll likely never need them(???), but if you don't.....seems like it will fail at the worst possible time.

[Boston Blackie]

Spoke to Bayside Marine guys, Our 3JH2-TE has a square 4 bolt Johnson pump which only accepts the $81 Yanmar impeller.

[Boston Blackie]

You grab the jumbo angle needle pliers from Harbor Freight and bent the tips in with a MAPP torch so they are a bit bowlegged so they grip the gap between the impeller lobes.

[Boston Blackie]

When I had the 3JH2-TE Johnson pump apart last winter for new bearings and seals I clamped the spline for the impeller in the vise and eased the notches with a triangular file so the impeller drops on and off rather than the near press fit as supplied. I figure the greased impeller will free float radially a few mils in use in the cam chamber which is OK and should be easier to pull out with the bowleg angled pliers for changeout.

[Dockhead]

Originally Posted by Boston Blackie

When I had the 3JH2-TE Johnson pump apart last winter for new bearings and seals I clamped the spline for the impeller in the vise and eased the notches with a triangular file so the impeller drops on and off rather than the near press fit as supplied. I figure the greased impeller will free float radially a few mils in use in the cam chamber which is OK and should be easier to pull out with the bowleg angled pliers for changeout.

If you use the proprietary Yanmar impellers with the threads in the end, and the cheap Yanmar special tool, then getting the impeller in and out is a snap.

[mowerandy]

Originally Posted by Wotname

Ain't that the truth!
But only if you carry it around on board - keeping in the shed at home negates the effectiveness of this technique.

Yep - can attest to this. Old impeller was still doin fine at 19 years with a spare new one in the nav table drawer. Shoulda kept a spare pump as well, cos the shaft seized solid necessitating replacement at 20 years since last full service. I expect that Diesel Neil (Minnards - Oz) coulda fixed it, but it needed a new shaft after my over-zealous application of "the encourager" trying to get it apart.
All good again now for another twenny

[DeepFrz]

Originally Posted by sailcrazy

My Yanmar 4JH-TE is mounted such that the impeller is in the worst possible place to access it. Guess I've been lucky, but the impeller that Yanmar mechanics put in 5 years ago is still going strong. I do carry spares, but.....if it ain't broke, don't fix it! What tool do you use to pull the old impeller out when you do change it? A needle-nose pliers?

Its a lot easier to replace it when you are parked than when you are on passage. If I were you I would replace it now.

[billgewater]

Thirty seven years on my boat. The main engine raw water pump failed in the Swan river (1978 Perth Australia). Plastic bag over the inlet grid on the hull. Fortunately we noticed the rapid engine temperature rise in time. The only sensible solution seems to be to have two hull inlets, so if one gets blocked ...... but I have survived without this second installation.
In Darwin I installed a Yanmar 1 GM purchased from a failing business. I sold the Kanzaki gear box then put a lay shaft on the flywheel to drive all sorts of things including a Tecumseh 1000 clutched compressor. I initially used the dinky inbuilt Yanmar raw water pump on the engine block for everything (condenser cooling etc.), but temperatures were a bit iffy. So I checked Yanmar replacement impeller prices and had a near stroke. So I installed a separate half inch Finspray (NZ) impeller pump to run off the lay shaft (no clutch). This pump needs manual greasing using screw down caps. It has been there since 1982 and looks like new. There is a spare impeller hanging nearby which I suspect is the reason the original Finspray works without fail ...Murphy's Law? The Finspray was an off the shelf bronze impeller pump. Any pump that has readily available parts would do.

[Kenomac]

Originally Posted by sailcrazy

My Yanmar 4JH-TE is mounted such that the impeller is in the worst possible place to access it. Guess I've been lucky, but the impeller that Yanmar mechanics put in 5 years ago is still going strong. I do carry spares, but.....if it ain't broke, don't fix it! What tool do you use to pull the old impeller out when you do change it? A needle-nose pliers?

Yanmar sells a tool for less than $20, maybe less than $10, I think I bought it on amazon. It's two bolts one inside the other.

[Bjorn_O]

I check mine once a year, when the boat is out of the water. I have changed the screws on the lid to Pin-wings to make easier as it is hidden and I need a mirror to see what I am doing. I use two screwdrivers to pry it out. If it looks OK, no cracks and the wings not bent, I use it another year. When assembling, I lubricate with a thin layer of vaseline.

[Dockhead]

Originally Posted by Kenomac

Yanmar sells a tool for less than $20, maybe less than $10, I think I bought it on amazon. It's two bolts one inside the other.

The only bargain ever from Yanmar. Someone forgot to add a zero to the price. Buy one before they figure it out!

Seriously -- this tool transform impeller removal from an awful fiddly job, which usually rips the impeller, to a 45 second snap. I wish my generator had a similar arrangement.