>
> > So, with all the cheaper portable units out there has anyone tried recently to install one? What the biggest hurdle....no liquid cooling?
>
> ALL of these machines are 20-25% efficient and the other 75-80% of the fuel's BTU output needs to be discharged quickly and efficiently in order
> to prevent overheating. Liquid vs. air cooling means absolutely nothing if the thing is crammed into a smallish enclosure with nowhere for that
> rejected heat to go. The Onans that came stock in our coaches are a pull-through cooling design (Onan's name is "Vacu-flo") that is specifically
> intended for the RV application and they move 2-3x as much air over the engine and alternator per unit time as compared to a more traditional
> forced-air cooling that is designed for non-enclosed operation. They expel the waste heat to the side of the coach where convection can take it up
> up and away - and if you add the Ragusa deflector from our GMC dealers then that heat is all horizontally ejected making for even better cooling.
>
> I follow closely the trials and tribulations of those (especially on fakebook) that get disgusted and throw away their Onan in favor of something
> they buy at walmart or horrible freight because they think the Onan is junk and something brand new must undoubtedly be better. The usual problem
> encountered with the newish unit is overheating when trying to run it inside the compartment either while going down the road or while parked with
> the compartment door up. They simply cannot get rid of waste heat fast enough and subsequently overheat and shut down.
>
> None of what I said addresses mechanical longevity and sound characteristics of the Onan's 1800RPM design vs. the 3600RPM models commonly used as
> replacements..that is another story. Re longevity: I have worked on a couple dozen Onans in GMC coaches and some of them have been 300-500 hour
> units and others > 1000 hours. The high time specimens run just as well as the young ones. I have *never* seen an Onan that smoked and puffed and
> had minimal compression no matter how many hours were on it. I recently obtained a 4kW Powerdrawer that had been abandoned in a horse barn for 25
> years and was completely stuck. I managed to free it up but differential compression score was terrible - 80/30 on each cylinder. After a little bit
> of work on the carb and points I started it up and ran it for about half an hour and now it scores 80/65 on each cylinder and has become my test
> unit for armature and field assembly repairs. There is no smoke, no oil consumption and it starts every time.
>
> I am aware of several success stories of people (particularly ones here on GMCnet) that have put in other generators and have had positive results
> - however I also highly respect those particular people's engineering skills and the ability to address the issues.
>
> --Jim
> Jim Miller
> 1977 Eleganza
> 1977 Royale
> Hamilton, OH
>
>
>
>
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Thanks for the explanation Jim....i would be more than happy to work with an Onan but around here they fetch 1500 plus for any model....if i could
find one reasonably i would certainly grab it.
--
Rich Mondor,
Brockville, ON
77 Hughes 2600
