Yanmar 1GM10 - Impeller problem

[mattyc]

My Yanmar 1GM10 engine has been going through impellers at a alarming rate. The failure has been that the rubber separates from the metal core so when the shaft turns the metal core just spins but the impeller doesn't turn. My last impeller lasted about 2 hours before failing. They fail on startup. I'm on my fourth one since October and I rarely use the diesel. The longest one lasted was about 20 hours. Any ideas on what is going on?

[AA3JY]

Correct impeller for that water pump? Sounds like the cover plate is squeezing the impeller a bit to much possibly causing heat build up to result in impeller failure. New gasket replaced as well? Also try flipping the cover plate..

[mattyc]

Originally Posted by AA3JY

Correct impeller for that water pump? Sounds like the cover plate is squeezing the impeller a bit to much possibly causing heat build up to result in impeller failure. New gasket replaced as well? Also try flipping the cover plate..

I noticed some scoring on the cover plate. The cover plate should not contact the impeller at all? Slightly thicker gasket needed?

[a64pilot]

Originally Posted by mattyc

I noticed some scoring on the cover plate. The cover plate should not contact the impeller at all? Slightly thicker gasket needed?

My cover plate is scored as well, I think that is very common.
I’d guess you have gotten a bad batch of impellers.
Maybe try a globe dry run?

[AA3JY]

Originally Posted by mattyc

I noticed some scoring on the cover plate. The cover plate should not contact the impeller at all? Slightly thicker gasket needed?

Scoring is typical.. OEM gasket is all that is needed. Should be some contact between impeller and cover plate. Is this impeller have the key way version (little bar down the middle of opening)?

Also check water flow for no obstructions..

[mattyc]

Originally Posted by AA3JY

Scoring is typical.. OEM gasket is all that is needed. Should be some contact between impeller and cover plate. Is this impeller have the key way version (little bar down the middle of opening)?

Here is a pic. No little bar. The impellers aren't OEM. I had 2 different brands , one Johnson and the other has no markings. They are the correct fit. Unlikely(?) both have manufacturing flaws but possible. I just put in my last impeller. The too tight cover plate theory might be correct. What else could it be?

[AA3JY]

Though a bit more expensive..I personally use Yanmar oem impellers.. When purchasing new impellers check impeller integrity by pulling on vanes 180degrees from one another and confirm no separation of bonding materials..don’t have to open the plastic package to do this.

[mattyc]

Originally Posted by AA3JY

Scoring is typical.. OEM gasket is all that is needed. Should be some contact between impeller and cover plate. Is this impeller have the key way version (little bar down the middle of opening)?

Also check water flow for no obstructions..

Water flow is good. I have kept my damaged impellers. Do you think is would be possible to glue the metal insert to the rubber to make them at least function over the sort term? 5200 or epoxy? I doubt I'm going to find spares in Marsh Harbor.

[AA3JY]

Marsh harbor has a yanmar dealer at Marsh Harbor Boat Works..was just there for parts..also a Yanmar dealer at Man o War Cay..is that where your at in the Bahamas?

[a64pilot]

You may actually, call Marsh Harbor boat yard.
It’s about the best option.
If your in Spanish Wells call R&B boatyard and speak to Robert, he can get one quicker and probably cheaper than anyone else, but nothing in the Bahamas is cheap, so don’t expect US prices, import taxes and VAT kill that.

[a64pilot]

As an emergency repair, I’d use an electric water pump before I tried glueing them back together, I’d say there is a zero chance of that working.

Yanmar doesn’t make the pump I don’t think, and I’m pretty certain they don’t make the impeller either, so buying OEM is just paying a higher price

[mattyc]

Originally Posted by a64pilot

My cover plate is scored as well, I think that is very common.
I’d guess you have gotten a bad batch of impellers.
Maybe try a globe dry run?

What is a globe dry run?

[a64pilot]

Originally Posted by mattyc

What is a globe dry run?

Different impeller, made from what looks like Urethane as opposed to “rubber”
It supposedly is more tolerant of being run dry for short intervals.
Made by Globe, but less likely to be found in the Bahamas for sure.

[Captndave1]

When you assemble the new impeller, coat the inside of the pump housing and the impeller blades with a thin coat of silicone grease, this will solve your problem

[sailm8]

I think your impellers are missing the flat spot on the inside metal collar. Can't really see it from your picture. Also several years ago there was a bad batch of OEM impellers that were defective. I would have thought they were all gone by now.