| Onan Spark Plug Problem [message #344513] |
Mon, 24 June 2019 16:25  |
Russell K.
Messages: 178
Registered: October 2016
Location: Dunedin, Florida
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I did my Onan maintenance early because the Onan appeared to be surging slightly under load. I changed the spark plugs, fuel filter, air filter, oil and oil filter. It appears to run fine now, but one of the spark plugs looks really bad. Here is a link to a picture of the two spark plugs removed.
http://www.gmcmhphotos.com/photos/onan-generator-maintenance/p66482-champion-spark-plugs-out-of-the-onan.html
Could it be carbon build up causing one of the valves not to close completely? I did run some sea foam top engine cleaner spray through the carburetor while it was running, according to the instructions, before I did the maintenance. My Onan manual recommends the "Onan 4C" spray engine cleaner, which does not appear to be available any longer. I changed the spark plugs just 73 hours ago, and the removed plugs did not look as bad at that time, although one appears slightly worse than the other.
Here is a link to a picture of the spark plugs I removed last time, only 73 hours ago.
http://www.gmcmhphotos.com/photos/onan-generator-maintenance/p63070-onan-spark-plugs.html
My Onan is not original, but it is 20 years old. Its an NHD series 6.5kW, Model No. 6.5NHDFB1L
Should I plan on removing the heads for carbon cleaning and valve cleaning?
Any other recommendations?
1978 Eleganza II, Dunedin, Florida
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