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Yanmar 1GM10 water pump impeller

Boffin

.
Aug 30, 2010
75
yahama 25 Hong Kong
The water pump in my newly installed Yanmar failed after 240 running hours.
The impeller was broken into several small pieces , and a groove of 0.5mm depth was formed in the brass cover plate . It is rather unusual for such short running hours, I suspected that the direction of the impeller was installed in a reverse direction resulting excess stress on the rubber material. I found several equivalent product other than the Yanmar product . One of the best is from Johnson pump serial no 09-1077B-9 made of Nitrile.
 

Attachments

May 20, 2013
10
Yamaha 25 Macau
These grooves reduce the pump pressure and subsequently their water flow.
The thermostat will divert only a small part of this water flow to actually cool down the engine. The most part of the water is discharged. So, provided your water temperature switch doesn't alarm, there is not a big deal.
Any way, when I found a deep groove in the water pump cover of my YSM8 I bought a new one but I never replaced it. I installed the old one with the external face turned to the internal side and it is working as a new one.
 

Boffin

.
Aug 30, 2010
75
yahama 25 Hong Kong
The deep groove indicated some misalignment during installation. Yes , it is simple to reverse the cover plate. But the broken impeller after 240+running hours is not acceptable . The water pump in my previous YSM8 last for 12 years required no replaceemnt .
 

jnovie

.
Jan 28, 2009
54
Yamaha 26 tall rig Marina Village Alameda, CA
The water pump in my newly installed Yanmar failed after 240 running hours.
The impeller was broken into several small pieces , and a groove of 0.5mm depth was formed in the brass cover plate . It is rather unusual for such short running hours, I suspected that the direction of the impeller was installed in a reverse direction resulting excess stress on the rubber material. I found several equivalent product other than the Yanmar product . One of the best is from Johnson pump serial no 09-1077B-9 made of Nitrile.

Impellers made out of neoprene are recommended for the engine cooling system pumps. Impellers made out of nitrile are recommended for bilge pumps or pumps for fuel or oil. If you decide to change to nitrile check with a trusted Yanmar mechanic first. I have a 1gm10 and inspect the condition of my impeller with each oil change. I usually change the impeller once a year. Probably more often than I need to but I don't want to take any chances and it is not all that expensive and a very easy job to do. I also suggest keeping an extra impeller and gasket on board for emergency use when underway.
 

Boffin

.
Aug 30, 2010
75
yahama 25 Hong Kong
Hi ,I am back. To fit a 1GM10 into the Y-25 ,you need to modify the engine bedding in the bilge . The original are two beam shape protuded on both side the bilge. You need to fix two strips of steel plate in the original bedding so the new engine seat can rest on it with the fixing bolts in different position . Not much ,just a few inches from the original. I saw other 25 fit a Yanmar 2GM which is more power of course. And I hear that a France marine engine -- forgot the name with Na?????? or the Bata which can direct fit into the original engine mounting position without modification.......pl check. Hope to post some pictures later, they are in other pC.
 

Boffin

.
Aug 30, 2010
75
yahama 25 Hong Kong
Here comes the picture. Pl note that you need to replace the propeller, the 1GM10 is R turn. Or you may need to adj the length of the shaft because of the new position of the engine.
 

Attachments

Boffin

.
Aug 30, 2010
75
yahama 25 Hong Kong
The 1GM10 has two weakness . The impeller of the water pump that I have mentioned, better to replace it at every 300 hours. Next is the VDO hour meter in the panel . It failed after 90hours, search in the forum found out it is common on most Yanmar marine engine with VDO meter. It is bad, I then install a US$10 quartz control meter which is fine for some 800 hours already.