Onan 6.5 gen anti siphon

[Jimmy]

While using the gen last year (after replacing the impeller), i noticed it took a bit of time before It started to spit out water out the exhaust, and on some occasions the over temp shut it down. So, while looking through the owners manual, I saw an optional anti-siphon setup. Where can I get one of these? Or will a simple very light spring flow check work on the hose just prior to exhaust? Other suggestions? I'd like to stay with standard if possible. I'm in the process of replacing the hoses this year so figured while I'm at it.....

Thanks for the help.

[Jimmy]

Did some digging and aswered my own question. Don't need the Anti siphon since the generator is above the water line. I did order a 1/2" flow check with a very light spring and ball. The hope is to trap water and hold it from the heat exchanger to the exhaust manifold. Hopefully this will hold water in the system so the impeller does not need to run dry until it eventually pulls the water up.

Although the impellers can run dry, id rather not run them as such and hopefully extend the life. We will see.

[prowlersfish]

Do you have a strainer before the check valve ? Check valves can get easily plugged . A honestly should not be needed .

[Jimmy]

Yes, there is a strainer, and agreed the check should not be needed, however, several times I had to pull the sea water hose off the pump and lower it until water flowed into it and then put my thumb over it while I quickly put it back on the pump. All this to 'prime' the pump. Otherwise is would not seem to suck the water up. Even with a new Impeller.

I had plenty of flow with the hose off, so not really any obstruction in the supply. Just had a hard time pulling in water. Hopefully the check will help hold it in there.

[prowlersfish]

A bad seal on the w/pump can cause it to suck air . Also you said something about running dry ? It your running Globe impellers , even thought they said the can run dry the don't prime as well . They also don't seem to pump as much .

[Jimmy]

Checked all the hoses thinking the same. Sucking air vs water, could not find any source as it is only the one hose, two connections.

Ill have to look at what impeller I put in there. Ordered what was on the parts catalog. Got a spare so i can look. There are other ones better?

[Big D]

I agree with Paul, there is something else at play here. I see you've checked the hose connections. Could be anywhere along the raw water circuit. The pump may be pumping fine but there could be an unseen issue. Take a look inside the pump housing to see if it's scored, make sure the cam in the pump is tightly fastened, ensure the cover gasket is in good shape and sealing properly, a small nick in the right place at the pump housing opening will cause problems. May also be a bad pump shaft seal though you can usually see a water leak once she's pumping. Confirm that you have the correct impeller for your application. If you have a raw water strainer, check both fittings and the cover gasket. Is the strainer below the water line?

[prowlersfish]

Also look at the intake hose . Mine was slightly porous . look for dry rot .

[Jimmy]

Ok, great, I do NOT want to pit in the check valve, but dont want to burn up impellers either. im gonna replace most all the hoses this spring anyway and double check the housing as suggested.

Yes, strainer is straight from the bottom of the boat. Well below waterline.