Onan 8kw not pulling raw water through

Jan 1, 2014
180
Hunter 42 Upper Chesapeake

Puesta del sol
Checked the strainer and made sure water was coming up thru hull.

Took intake hose off just as it enters impeller. Poured water down tube - did not back up so must be going out the bottom.

Started and looked inside entry to impeller. Impeller spinning.

What else should I be checking?
 

NYSail

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Jan 6, 2006
3,048
Beneteau 423 Mt. Sinai, NY
Does this model have an exhaust elbow that could get clogged...... detach from exhaust side and turn engine over briefly and see if water exits hose. If not it's within the heat exchanger or hoses
 
Oct 2, 2008
3,807
Pearson/ 530 Strafford, NH
Owe me a beer. Glad you were able to get back to sailing.

All U Get
 
Jan 1, 2014
180
Hunter 42 Upper Chesapeake
Thanks. 1-beer

To make things fun the engine impeller obliterated itself the next day. Sigh not even a year old. The one prior to that had been in for 5 and had not failed when I replaced as a general maintenance items
 

SG

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Feb 11, 2017
1,670
J/Boat J/160 Annapolis
Nettles or grass blockages can obliterate them -- was your strainer "clear"? Even then, it can be a temporary blockage on the exterior which "clears". If the impeller turns and doesn't get "cooled", it will deteriorate in a short period.

Also, when you reinstall one, use some Teflon (non petroleum base) grease, like SuperLube. The initial spinning of the impeller before the liquid comes in is rough on the impeller. It also makes it easier to slide the impeller in -- but you have to have to wipe your hands off ;^))).
 

NYSail

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Jan 6, 2006
3,048
Beneteau 423 Mt. Sinai, NY
And make sure it's installed correctly.... had a friend who installed
One with vanes in wrong direction.... failed quickly
 
Dec 19, 2006
5,809
Hunter 36 Punta Gorda
A friend had his Gen stop running because over heating on new to him boat and spent
hours checking everything with me helping and did not change anything and it ran fine and no
idea what was wrong and did change impeller a day later.
Nick
 
Dec 25, 2000
5,702
Hunter Passage 42 Shelter Bay, WA
Looks like a new impeller solved the problem - old one was in bad shape
Hi Keith, glad you found and corrected the problem. Our Onan 8kw Genset has been pretty reliable over the years and usually a simple fix to a running or starting issue. When we first purchased Belle-Vie I cranked the engine one to many times (before I knew about warming the glow plugs) and popped the inline starter solenoid fuse located on the starboard side of the engine. That was quite the trouble shooting experience. It was another owner on this site that pointed out this fuse that was tucked in close to the engine block and out of sight even with a mirror. After much poking and pulling it finally popped out, replaced the blown fuse and she fired right up.
 

SG

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Feb 11, 2017
1,670
J/Boat J/160 Annapolis
If you look at the inside of the pump section that holds the impeller, there is an insert (or the whole body, itself) which compresses the impeller as it spins. That's what makes it a pump. If you lube the impeller properly, it probably would just readjust even if you insert it with the vanes the wrong direction. If you don't lube it, then the impeller just gets stressed.

I think that if you have an impeller which has been sitting on a shelf for ten years, it can be more brittle. I wouldn't buy a lifetime supply and keep them on the boat in the heat.