Easy fix for Onan Quiet diesels.

[Ucbyrickg]

We were in freezing temperatures and the generator would not start.

After returning home and doing some investigating I determined that all three glow plugs had failed.

This problem is very easy to test and repair with a multimeter and a few hand tools.

The problem is that no one stocks these glow plugs and it can take one to three days to order them in. I suggest having a set to fit yours in case of emergency.

Generator starts and runs better than before especially after running fuel treatment and doing a complete service.

Also found a small rats nest in the breather box and will be fashioning a screen to protect the intake hole beneath.

I hope this is helpful to someone in the future.

Rick

[CountryB]

Did you test by measuring resistance from electrical connection to ground with your ohmmeter?

If so, what is the correct/proper resistance for a good glow plug?
Or did you just test for an "open"?

[Ucbyrickg]

Originally Posted by CountryB

Did you test by measuring resistance from electrical connection to ground with your ohmmeter?



If so, what is the correct/proper resistance for a good glow plug?

Or did you just test for an "open"?

I just tested the hot feed terminal while holding the cold start button before actual crank, making sure I had power. Then removed each glow plug individually and connected to the power source with threads on ground, the plugs never got hot. I tested each new one the same way and smoke came off them instantly and became very hot.

I never tried resistants Im not sure what reading I should get but these things were gone.

Another quick test to see if it is glow plugs is disconnect the plugs feed and spray a very small amount of brake clean in intake, if it starts, probably a glow plug issue.

Never spray starter fluid or have glow plugs powered or you could get a fire.

Rick

[azpete]

i got ngk glow plugs for my onan at napa auto parts. had them in stock.
if you test the plug with voltage, make sure the very end of the tip of the plugs get hot, and it heats up evenly for most of the heating surface. if the very end of the tip doesnt get hot, and it heats up part way up. its also a bad plug.

[Ucbyrickg]

Originally Posted by azpete

i got ngk glow plugs for my onan at napa auto parts. had them in stock.
if you test the plug with voltage, make sure the very end of the tip of the plugs get hot, and it heats up evenly for most of the heating surface. if the very end of the tip doesnt get hot, and it heats up part way up. its also a bad plug.

I called all my local parts stores including Napa, minimum next day by noon, they all claimed they don’t stock glow plugs anymore.

I ordered them through Napa no problem but closed on Sunday.

I tested the tips on an old rubber hose for heat instead of my finger.

Keep in mind I ruled out intake and fuel delivery first.

Thanks

Rick