Onan Generator going Tic Tic Tic

[Larry Dedrick]

Gerald and Others:

                I was reading a post from 2010 regarding the onan gen. and you have done some work yourself on yours. I did not realize there was a fan belt that should be changed periodically. If you find time, could you give me some idea on how to go about this and a few other preventive maintenance tips on the gen.  Now for the rest of the story:
                The generator was running and all of a sudden it sounded like something had bogged it down, with a constant rhythmic ticking sound. I shut the generator down to check oil and coolant and all was good. The Gen was restarted and same issue. It sounds like an injector is sticking, could this be a reasonable diagnosis? There are times the gen starts immediately and times it takes a few attempts, injector maybe?  But this is the first time it labored and had the Ticking sound.
                 I plan on doing the work myself as long as there is not a need to remove Gen.

                  Thank You in Advance for your Knowledge.                                  Larry D.

[Tom and Pam Brown]

Larry, is your generator side or front mount?
The tic tic tic sounds like the priming pump.

[Larry Dedrick]

Tom:
           The gen. is side mounted, The constant ticking is while it is running and the gen engine is slightly bogged. would the priming pump cause the bogging down?

             Thanks           Larry D.

[Edward Buker]

Larry,

The ticking of the priming pump would be heard with the generator stopped and is built into the delay when you hit the gen start button along with the glow plug preheat which takes place during that interval. You can judge that noise with the other ticking you hear. I do not know if you have a sticking injector but I have not heard of anyone else reporting that symptom so it would be a bit rare. The fact that the engine bogs down could be injector or a sticking valve logically. I'm sure a long time mechanic working on Onans would have a good set of clues.

You probably have the 10KW HDCAA generator. In this post there are references as to various temperatures that you will get in specific spots (block, radiator, etc) using an IR gun with a good or bad belt. If my temps were inline with a good performing belt then I would not change it. If I had to pull the covers to do other things then I would change the belt. There are several possible belts and on the page with the graph are the temps and the belt PNs.
The worst part of the job is getting the screws on the back of the top cover out while you are positioned between the slide and the genset . Long reach and limited space. If I could find suitable ones, I was going to buy some stainless push pins with a ball detent and replace the back bolts but I never got to it. If you get the top cover off it is a couple of hour job after that. For tensioning the new belt I found I could use a small bar clamp to adjust the alternator position which was handy and easier.

http://forum.bacrallies.com/m-1302907037/s-6/highlight-Generator+overheat/#num6

Later Ed

[Robert Mathis]

Larry, a sticking or partially clogged injector will cause rough running and heavy smoke from the exhaust. A steady ticking is normally a valve tapping, but could also be caused by a "feather" on the belt hitting the shroud. Is the ticking constant in sound level and cadence?

[Larry Dedrick]

Robert:
              Yes, the ticking is constant and rhythmic, the frequency is steady. If it is a valve, any quick fixes? I have torn down auto engines and reassembled, so if I have to go there I can, but with limited space on this coach, I may seek an Onan repair facility. The valves have never been Lashed, as far as I know and I saw in the Onan manual that should be done after 1000 hrs, I have 1200 hrs.
              Any advice is appreciated.

                  Thanks              Larry D

[Larry Dedrick]

Ed:

          Thanks for the advice, I have located a facility in Daytona Beach, which is close to where we live, so I may take it there. They are an Onan repair facility. Wanted to save dollars doing what I could, but when I here, a possible valve, I think I will leave it to the pros.

               Thanks Again:                        Larry D

[Larry Dedrick]

To All:
            Was at the coach and started the gen, and no unusual noise, at least for about 4 minutes and then the noise returned. I must correct the description of the sound. While it may sound as though it is ticking, it would be better described as a metallic or ceramic rubbing, possibly in rhythm with the fan or generator itself.
            Any ideas?

               Thanks                Larry D

[Gerald Farris]

Larry,
There were a few bearing failures in the generator section of 10K and 12.5K Onan units. If that is what your problem is, the generator must be removed from the coach for repair.

Gerald

[Robert Mathis]

Larry,
There is a big Cummins facility in Jacksonville, right off I295, just North of I10. I have had service there and they are very competent. BTW, I live just North of you off exit 298 on I95.

[Larry Dedrick]

Gerald:
            Thanks for that information, that may explain the bogging down of the engine. I don't want to operate the gen anymore, for fear of doing more damage, except for the facility that will do the analysis.

                         Thanks:                  Larry D.

[Larry Dedrick]

Robert:
         Thanks for the information. If I don't feel comfortable with the facility I'm taking the coach to, I will consider taking it to Jacksonville. Maybe we will run into you at a rally some time.

                                             Thanks again,                    Larry D.