Re: Onan Raw Water Cooling System Maintenance

John Clark

Hi Bill S,
     I cut my teeth on a 66 Chevy with 283.  She survived my "cleaning" with "Engine Flush."  I don't know about how a diesel will respond.  I guess in theory it should be ok.

My SM #37 was repowered in 2002 with the TMD-22 and the 6.5KW Onan, today there is about 4400 hrs on each.  I also observed the clear oil after change in the TMD and the instant dirty oil after the change in the genset.  You are right on that the gravity drain on the genset does not get all the old oil out of the oil pan, and it drains very slow.  Takes maybe about 30 minutes to finish the gravity drain.  I use a hand vacuum fitted down through the oil dipstick tube to get the remainder out.  The first time I did this the oil was still a bit dirty, so I poured a liter or two into the motor....enough to just reach the dipstick then ran the motor for a few seconds and drained the oil again.  It has been clear after change ever since.   

                       Regards,  John

John Clark
SV Annie
Le Marin, Martinique

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