old onan generator

[aurora]

i have a 1968 gas powered onan generator. she runs great and i just replaced the impeller and tuned it. but i'm confused as to whether it also has anti-freeze. there are 2 drain plugs on either side with thermostats mounted above. problem is that theres no place to fill with anti-freeze. i know that i can just unscrew one of the drain plugs, and see what comes out (duh), BUT IM RELUctant to do that if i dont have a place to fill it back up if it is antifreeze. the manual is confusing, and says that i have to remove the thermostat units to flush out the system, but seems a bit involved, if just to top off with antifreeze?? anyone have an opinion?

 

[SeaEric]

Today, I had a mechanic do a survey on a 1966 Hatt with a (diesel) Onan 6.5 genset. To my surprise, he reported that this unit is raw water cooled. I had no idea that such a thing even existed. Even more amazing is that it still seemingly runs fine and makes power.

 

[aurora]

they are amazing machines. mine runs quiet and smooth and puts out very level elec

 

[yachtsmanbill]

My 1969 6.5Kw MCCK Onan is fresh water cooled (anti-freeze) The heat exchanger is a SenDure unit which is shown to the right with a radiator cap on it. If yours doesnt have this, its raw water (seawater) cooled... ws

 

[aurora]

mine is an mcck also, but does not have that cooling unit. so these things can be raw water cooled only? is yours both raw and fresh?

 

[yachtsmanbill]

Youll need to master a bit of nomenclature here... it pertains to a myriad of subjects boat related.
Mine is freshwater cooled. That means that seawater is pumped through a heat exchanger with anti freeze circulating through the block. The HE is no more than a water cooled radiator. Yours appears to be raw water cooled, that is seawater pumped throughout for cooling. Typically, (salt water) thats bad on engine blocks and assorted coolers, manifolds and whatever else is cooled on any particular unit.
Mine has a jabsco rubber vaned seawater pump, plus a conventional centrifugal pump to circulate the hot anti freeze. Yours probably has just the rubber seawater pump. Run it until it dies! ws

http://www.sen-dure.com/

 

[boatwright]

i dont know if you boat in fresh or salt water. fresh is less corrosive so raw water cooling is less harmful.

 

[REBrueckner]

Sounds like your generator is raw water cooled....no fresh water, no coolant ....it would not have an expansion tank nor radiator cap for filling...raw water is pumped through the normal cooling areas and out the exhaust. So the head is subject to salt water corrosion.

You can always add fresh water cooling....if you are in salt water....a good winter project if you are interested..you would need to add a fresh water circulation pump, an expansion tank and fill cap, and a heat exchanger.

My Dad and I did that with a 1961 3 KW Onan diesel Gen...worked like a charm...all was well with the cooling system for the 22 years we owned it.

 

[yachtsmanbill]

I'd buy a junk unit with the parts to convert...The Sendure HE by itself is almost $1100.00 !! Plus the pumps etc etc... Aurora... WHERE ARE YOU LOCATED... ?
I wish everyone would list their homeport on their profiles! Great Lakes or ocean makes a big difference in a solution to problems like this! ws

 

[34Hatt]

You can always add fresh water cooling....if you are in salt water....a good winter project if you are interested..you would need to add a fresh water circulation pump, an expansion tank and fill cap, and a heat exchanger.

If its been in salt and is raw water cooled do not waste time converting you always will have problems they do not recommend it!

Oh yeah those units came both ways fresh water was a option.

 

[REBrueckner]

"If its been in salt and is raw water cooled do not waste time converting you always will have problems they do not recommend it!"

Who is "they"???? What "problems"??

Such "hearsay" evidence is not permited by rsmith!!!!

 

[ppat324]

"If its been in salt and is raw water cooled do not waste time converting you always will have problems they do not recommend it!"

Who is "they"???? What "problems"??

Such "hearsay" evidence is not permited by rsmith!!!!

Hey Reb....why are you bringing up rsmith? I cant find were he has said anything on this topic at ALL...ppat

 

[Boatnut]

If its been in salt and is raw water cooled do not waste time converting you always will have problems they do not recommend it!

Oh yeah those units came both ways fresh water was a option.

Just curious here, who are they, and what is the reason not to convert to a fresh water system, and what kind of problems will it cause?

 

[67hat34c]

Agree, raw water cooled mcck in not worth any upgrades. All Heat Exchange units have the same HE, the tall cylinder as show in willies photo and all located on either side of the exhaust manifold though mine was detached and mounted remote by prior owner (though not clear y). Either way you will have a raw water pump mounted high and another oberdorfer circulation pump mounted lower, all run by same belt.

 

[34Hatt]

Just curious here, who are they, and what is the reason not to convert to a fresh water system, and what kind of problems will it cause?

Just about twenty different marine mechanics that had said this over the past 30 years!

Do you want names and s.s #

The salt causes a coating inside the block and a fresh water system can not keep it cool as cool as raw. There have been some that acid wash and done other chemical cleaning to the block with some fair result. But as I said it not worth it specially on a old old unit.

REB you can't find this with Google I would think you can find it, since I know I have read other stating the same problems.

 

[jim rosenthal]

I think it's pointless to convert an seawater cooled antique generator set to FW cooling, unless it's in perfect shape, used to run in fresh water, and you happen to luck into all the parts to do it by finding a spare set with what you need- real cheap. Otherwise, you should just run the unit as it was built until it drops dead, despite keeping up the maintenance, and then replace it with a modern FW cooled unit. Converting the old unit is "Lipstick on a pig", indeed.

One of our members is looking at a boat with such a genset and asked me for recs for a new one, down the road. I suggested NL or Kohler or WB, but I am interested in anecdotal evidence on other brands as you all see fit to provide it. We also have satisfied owners of NorPro and NextGen units, I remember- anything else anyone wants to comment on?

 

[yachtsmanbill]

I agree there my good doctor! Run the pig until it dies, then sell the leftover parts. My old freshwater MCCK runs like the day it was installed albeit oil leaks, but what the heck....
The anectdotal addendum from me is the lousy parts availability from Westerbeke. I have a 20Kw for the sub, and parts are astronomical! The fuel shutdown solenoid that looks like an oil pressure sender (kind of) lists at $275 and I bought one from a fuel injection shop for $12.00! The freshwater pump was $275 from WB and is merely a Datsun 2.3 L pump with proprietary changes. It needs an exhaust manifold (aluminum in seawater!!) that runs about $900.00 The list goes on... I would never recommend a WB unit to anyone. My 2C's. ws

 

[Avenger]

It really doesn't matter that much, all of these companies are thieves. We sold a whole new turbo for a Koehler cheaper than Koehler's pricing for the repair parts. The worst part is we sold it to a Koehler dealer.

I've still got the old one sitting on a shelf as a reminder. Cute little bugger, just a little bigger than my fist.

 

[REBrueckner]

"The salt causes a coating inside the block and a fresh water system can not keep it cool as cool as raw. "

New science!!!

Right here on Sam's!!!

Raw water cools better than fresh!!!

Good joke.....

But as I recently posted in another discussion, iron oxide build up (growth) associated with raw water can affect engine cooling water flow. This is likely permanent.

On a more serious note, if your point is that corrosion may have taken most of the life from the unit, and fresh water cooling is probably not economical as a result, as I think Jim Rosenthal suggests in his post, THAT makes sense.

And for someone who has to pay prevailing labors rates for a mechanic, and new retail parts prices, it's likely NOT economical.

 

[jim rosenthal]

The reason I don't like Onans has to do with the fact that Onan squeezed laws through the MD general assembly years ago that gave them an exclusive for the entire state or something slimy like that... I recall reading it and was furious. They had a monopoly and no one else could sell parts etc. I don't remember all the details but it was a great example of using the state government to give yourself an unfair advantage... I resolved then to buy anything but an Onan genset henceforth and forever. I think I found this out by trying to buy Onan parts and being appalled at the prices, and then did a bit of digging.

Of course there are no bargains on parts for any of these units, but a comparison might be very helpful; I don't know that I've ever seen one. If I cna find time, I might look into this and post it. Ought to be educational to say the least.