Onan Gen shuts down sometimes

[dad's turn]

1999 olan gen 8.0 mdkal shuts down after running 15 -20 minutes but not all the time, I haver changed water pump and 3 sending units. Cleaned out intake lines and checked everything I can think of.... HELP before I loose what little hair I have.

 

[Four Suns]

Does it give a flashing error code on the start switch/light?

 

[dad's turn]

This unit has no gagues or lights on it.

 

[aquadancer]

I experienced similar shotdowns with my Westerbeke recently. After checking all safety switches and changing the impeller, it turned out to be a loose strainer lid which led to slow overheating. Has been running fine since. Hope your problem is just as simple.

99-vintage generator in 02 boat?

 

[dad's turn]

Spent 2 hrs last night rechecking, Found that if I froced water from the hose into the system gen would run for over 1 hr. But when run self contained would only run 15 mins before shut down. Checked the flow and was close to 5gals a min. Any more thoughts

 

[osd9]

Gary:

How/where did you ''force" water into the system? From the strainer, at the heat exchanger, etc, etc. Did you check your underwater strainer? It may have growth on it limiting the amount of water that can be sucked up.

 

[dad's turn]

I remove the hose off the strainer. Strainer, Sea cock and screen look like new. Is there a change able impeller on the fresh water coolant side? That seems to be the only thing I have not had apart.

 

[osd9]

..... Is there a change able impeller on the fresh water coolant side? That ....

Yes...but from your first post....

....I haver changed water pump....

I, and possibly others, thought you changed the impeller.


Anyway, odds are that your impeller is bad and you need to replace it. However, there is a good chance that some of the pieces have found their way into your heat exchanger and you may have to do some 'fishing'....

 

[dad's turn]

I have changed the raw water impeller but not the one on the coolant side if it has one. I have had the heat exchanger off and clean it out.

 

[osd9]

It runs fine when you force raw water through the raw water circuit. That indicates an issue on the raw water side. Your sig says that you are in MA, so I assume you have cool raw water to suck up. BTW your sig says that you have a 2002 300DA, again, I have to assume gas motors, but your issue is with a diesel genie....maybe some updating is in order....

Back on topic.....unless the temperature of the 'hose' water and 'raw' water are that different, I would still think that the issue is in the raw water circuit not getting enough water to keep things cool....other than that....I'm out of bullets....anyone else????

You are positive that you do not have growth on the 'underwater' grate on the bottom of the hull?????

 

[dad's turn]

ods9, Thanks for your help. Gen is on the other boat (the one I let fish on), Sea stainers are clean, Might the pump be worn on the raw water side, or could the cold water from the hose cool the heat exchanger down enough that the coolant does not over heat. One thing I did notice was that the coolant level did not move up or down at all last night even after running 2 hrs. And to boot no factory service in MA for this unit.

 

[osd9]

One more bullet....or just another blank, but what the hell, I'm slow today....when you replaced the impeller, what was the condition of the impeller vanes and what was the condition of the impeller housing ...any scoring? Was there wabble on the impeller shaft and/or do you see any water dripping around the outside of the impeller housing? Also, you may want to take the impeller back out and confirm the keyway is still there....Ok...that was more than one bullet, but like I said....I'm slow today....

 

[dad's turn]

Everything looked fine, I may just have to change the coolant side water pump as the raw water seems to be working. Thanks I will let you know what happens

 

[CaptSteve]

I know it is about a month too late and probably already worked out but the Onan has a raw water pressure switch right after the raw water pump. they tend to go bad by clogging up in salt water... actually, they tend to rust up and fall off. you can take the leads off and connect them together and see if it continues to run.

 

[The Bill Collector]

I know it is about a month too late and probably already worked out but the Onan has a raw water pressure switch right after the raw water pump. they tend to go bad by clogging up in salt water... actually, they tend to rust up and fall off. you can take the leads off and connect them together and see if it continues to run.

Capt. Steve you are about 2 years too late.........

But I'm sure some Onan guys out there still appreciate it

Thanks, Mark