Seawater Impeller Change on Yanmar 4JH

[a64pilot]

Do NOT use vasoline or any other kind of petrochemical, it will attack some types of rubber, likely not an impeller, but why take that chance? Use either surgical lube (KY) or similar, I know you have some or dish soap. Those do not attack rubber, and are both water soluble, vasoline is not and will never wash off, it will likely end up in your heat exchanger and one day you will have no idea what that stuff is, or where it came from when you clean the heat exchanger

[Safari38LH]

Here's what the Yamaha tool looks like. Note, not all Yamaha impellers have treads.

[daletournier]

Originally Posted by Jeanneau 45.2

I have a 4JH3-TE with the same limited access to the impeller issue. Do yourself a favor and buy OEM impellers with the threaded insert. With the Yanmar jack screw tool, removal is a breeze. Worth the extra cost of the OEM part, especially if it prevents collateral damage to the alternator.

Absolutely 100% agree, just did mine , it was a real b........! Because it wasnt threaded and I had to pry out with no access. Never been out before, limited access to port side of engine, could see or feel but not both.
Ive bow put in a threaded impeller as previously suggested and a speed seal cover, no risk of losing small screws.
Btw my temperature wasnt up and PO assured me I didn't need to change impeller, check out photo below.

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[daletournier]

Here's the little puller.

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[hafa]

Originally Posted by carlfmiller

I see some people get by with pliers or channel lock so I'll try that first.

Note that when removing the impeller with channel locks, it's very easy to pull the impeller in such a manner so that it's no longer parallel to the shaft, causing it to bind. If this happens, a GENTLE tap with a hammer on the impeller will remove the bind and allow you to continue to pull out the impeller.

Originally Posted by DeepFrz

I bet the engineers that designed those pumps are still laughing.

Yep, impeller replacement is a regular maintenance item; the design is such that they invariably shred themselves. Fortunately for us, access to the pump is pretty easy via a thoughtful panel on the engine bulkhead.

[a64pilot]

Now your issue is where did all the missing pieces go?
If your lucky they are all in the heat exchanger, if they get through that then next I guess in the exhaust elbow, and if it sticks in the water exhaust hole it may be hard to remove?

[daletournier]

Originally Posted by a64pilot

Now your issue is where did all the missing pieces go?
If your lucky they are all in the heat exchanger, if they get through that then next I guess in the exhaust elbow, and if it sticks in the water exhaust hole it may be hard to remove?

Yep, after the pump there is the oil cooler, that's my first stop then heat exchanger. I'll start looking shortly, its been that way for some time I'd suggest.

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[Cabo Jim]

I use the Yanmar impeller puller also on my 4JH4E. a Couple of years ago a sister ship very kindly gave me a spare blue impeller. They are the self lubricating type and are expensive but in my opinion they last much longer and I have run mine dry for 5 min.(due to an air lock in the raw water intake after launching off a good sized wave in an ocean inlet and exposing the raw water inlet to the air, this is not a good time to overheat your engine and have to shutdown it down). After inspection the impeller is in excellent condition! This same thing happened with the normal OEM black impeller and in a few minutes every impeller lobe was gone. Go big or go home!

[Safari38LH]

Impellers for my Yanmar 4JH2E cost about $80 at most dealers. Anyone tried with success the Blue ones at $40 apiece or has anyone found a place to buy Yanmar impellers cheaper?

[Vasco]

Originally Posted by joemcw

With regard to impellers, it is wrong to wait for it to fail before replacing, all kinds of compound issues associated with waiting for failure!
Treat it like airplain parts and change on schedule regardless of condition.
Search: impellertool.com (may be tools, plural)
It is a one hour job for a qualified technician, maybe hire an expert, that's what I started after my first "self" replacement which took most of one day.

A one hour job for a qualified technician? You have obviously never changed an impeller on a 4JH ( up to 3E) with limited access on that side. Remove alternator, remove water pump, change impeller

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[Vasco]

Forgot to add " go to hospital to get hands bandaged" 🤣

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[a64pilot]

Originally Posted by daletournier

Yep, after the pump there is the oil cooler, that's my first stop then heat exchanger. I'll start looking shortly, its been that way for some time I'd suggest.

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Before I tore it all apart I think I'd try backflushing it with a hose, disconnect the hose to the exhaust elbow, connect a water hose there and let it fly, water will flow backwards of course and out the thru hull, any rubber pieces may get stuck in the water pump, so maybe remove the cover?

Or just let sleeping dogs lie?

[a64pilot]

Originally Posted by Vasco

A one hour job for a qualified technician? You have obviously never changed an impeller on a 4JH ( up to 3E) with limited access on that side. Remove alternator, remove water pump, change impeller

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On an Island Packet the whole side of the engine enclosure comes off, about a three ft on a side cover, sit down comfortably on a cushion and it's literally about a ten minute job, likely faster if I had one of those pullers.

It's access that is the key of course, but I can do it easier and faster than changing oil, a 1 beer job


However if i had to remove the starter to remove the pump, I'd likely R&R with my spare pump and then overhaul the pump for the next time. I don't want to have to go through all that just to have a seal start to leak ten hours later

[a64pilot]

Originally Posted by Safari38LH

Impellers for my Yanmar 4JH2E cost about $80 at most dealers. Anyone tried with success the Blue ones at $40 apiece or has anyone found a place to buy Yanmar impellers cheaper?

Are you talking about a Globe dry run impeller? If so , yes that is what I use. I was told they last longer than OEM, but they are not threaded for that neat puller

[daletournier]

Originally Posted by a64pilot

Before I tore it all apart I think I'd try backflushing it with a hose, disconnect the hose to the exhaust elbow, connect a water hose there and let it fly, water will flow backwards of course and out the thru hull, any rubber pieces may get stuck in the water pump, so maybe remove the cover?

Or just let sleeping dogs lie?

Good point, I'll give that a shot.

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