Howard Eisenhauer wrote:
I'm looking at buying an Onan genset. It's a late 80's vintage 4 cyl
aircooled diesel unit, 120/240 single phase. Seems to be the same
model unit shown here-

http://cgi.ebay.com/ws/eBayISAPI.dll...ayphotohosting

As far as I can tell it has about 1500 hours on it since it's last
rebuild. I had the seller fire it up today & after warming up it was
blowing white smoke . The owner sez it was fine last time he ran it
back in June. It also seemed to take a while to settle down before it
ran evenly although there may have been some air in the fuel line.

Q.- Any ideas what the white smoke is all about? Is this likely to be
a tuneup item or something more serious?

Q.-What's a rebuild on one of these things cost?

Q.- Anything in particular I should be looking for/concerned about
with one of these units?

Q.- How much do you think its worth?

Thanks,

Howard.


A good diesel should start and run well right from the start, assuming
all is well with the fuel system. I've seen truck diesels that haven't
run for 15 years start right off with a pull and run smooth once they
warm up. They'll smell bad till the old fuel gets burned, and smoke some
from the stale fuel, that might be what you're seeing. Even if he ran it
in June, the fuel could be years old.

It's going to be expensive to rebuild. You can probably get the
injectors rebuilt for $50-75 each, $300 and up for the pump, plenty more
for major engine work. If I bought it thinking it needed a rebuild I'd
not give much more than scrap price for it.

Check the fuel filters, make sure they're not full of water. If it's
starving for fuel it might act and smoke as you describe, it won't burn
well if the pressure at the injectors is low. If you can get a little
time alone with it it'd be best, that way you can check things out
without him seeing simple solutions. If you can't do that, have him
change the filters, run the fuel out and refuel it. That should at least
clear up the rough running and smoking issues, or demonstrate that
there's some other reason for them.

John

"JohnM" wrote in message
...
Howard Eisenhauer wrote:
I'm looking at buying an Onan genset. It's a late 80's vintage 4 cyl
aircooled diesel unit, 120/240 single phase. Seems to be the same
model unit shown here-

http://cgi.ebay.com/ws/eBayISAPI.dll...ayphotohosting

As far as I can tell it has about 1500 hours on it since it's last
rebuild. I had the seller fire it up today & after warming up it was
blowing white smoke . The owner sez it was fine last time he ran it
back in June. It also seemed to take a while to settle down before it
ran evenly although there may have been some air in the fuel line.

Q.- Any ideas what the white smoke is all about? Is this likely to be
a tuneup item or something more serious?

Q.-What's a rebuild on one of these things cost?

Q.- Anything in particular I should be looking for/concerned about
with one of these units?

Q.- How much do you think its worth?

Thanks,

Howard.


As preciously mentioned the smoke is most likely from the fuel system.
Sitting since June is not that long for a diesel. Might be worth going back
and having another startup to see if the smoke went away.
Check the filters and see how new they are, check the water drain as well.
If they look ok, it might just mean that the thing has been maintained.
1500hrs is pushing it on a rebuild depending on what you plan to use it for.
What was rebuilt would be a good question. Normally the first thing to go
is the injectors and the pump. The injector pump tends to get pricey
rebuilding or new, depending on how common they are.

Keep an eye out for any ether cans lying around, meaning the machine is a
"dope addict". In my limited experience this usually means that there is
something wrong with the injector pump, again costly.

Would not think that air was in the lines as injector pumps are pretty picky
when they see air and you would see a cylinder misfire, or not even start
(or need the ether to get her running) if there was any type of air getting
in the lines.

Rebuilds get pricey on all diesels. I would think if the price is right and
you plan to use it for personal use, than jump on it. Clean the fuel out,
run some cleaner through the system, change the oil, check the rubber fuel
lines, you might see her purring fine. If she smokes a little well so be
it. Many a diesel smoke, and might outlast all of us. If after all that
you think it needs a rebuild and the smoke is still white, start with the
fuel pump (cheapest) and then the injectors and the injector pump. I say
this as there is no reason to rebuild the motor as it is, without redoing
the fuel system in a diesel, as it is normally the first to go.

No expert by any means, so take it for what it is worth. And God forbid, do
not let the run out of fuel.

--
Chris

If you can read this, thank a teacher. If it is in English, thank a
soldier. If it is in ebonics, thank your Congressman.

Ignoramus27122 wrote:
On Thu, 01 Sep 2005 04:42:16 GMT, Howard Eisenhauer wrote:

I'm looking at buying an Onan genset. It's a late 80's vintage 4 cyl
aircooled diesel unit, 120/240 single phase. Seems to be the same
model unit shown here-


Is it Onan DJC? If so, I have an Onan DJE, a very similar unit, only 2
cylinders instead of 4.

http://igor.chudov.com/tmp/onan/Diesel/


http://cgi.ebay.com/ws/eBayISAPI.dll...ayphotohosting

As far as I can tell it has about 1500 hours on it since it's last
rebuild. I had the seller fire it up today & after warming up it was
blowing white smoke . The owner sez it was fine last time he ran it
back in June. It also seemed to take a while to settle down before it
ran evenly although there may have been some air in the fuel line.

Q.- Any ideas what the white smoke is all about? Is this likely to be
a tuneup item or something more serious?


white smoke is unburned, atomized diesel fuel.


Q.-What's a rebuild on one of these things cost?


A lot, but... Why would you need a rebuild? They will outlast you.
To get rid of the white smoke.

Q.- Anything in particular I should be looking for/concerned about
with one of these units?


If it starts, and runs, it is in a good shape.
Except that it is obviously running on 3 cylinders (or less).
If you can crank it over by hand (with the injection pump set to
shutoff), you can see if there is an obvious lack of compression
on one cylinder. (I think it is pretty clear, even from this
distance, there will be.) You might be able to determine which
valve (if any) is the cause. If intake, it might just be a sticky
valve, and an oil change and a warmup to full temperature might
clear it up. If exhaust, that could be a burned valve, which will
take a little more work and money to fix. Some Diesels have emergency
shutdown mechanisms that lock the exhaust valves open in case the
governor or fuel pump malfuctions. If this engine is so equipped, it
could be that the emerg. shutdown mechanism has gotten out of adjustment
and is holding one valve open. Most of these schemes have a system of
levers that come through the valve cover, so it should be quite obvious.

Jon

"Jon Elson" wrote in message
ervers.com...
If it starts, and runs, it is in a good shape.
Except that it is obviously running on 3 cylinders (or less).
If you can crank it over by hand (with the injection pump set to
shutoff), you can see if there is an obvious lack of compression
on one cylinder. (I think it is pretty clear, even from this
distance, there will be.)

It's not necessesarily a loss of compression. The same white smoke symptom
can come from a damaged or dirty injector tip that isn't properly atomizing
the fuel.

LLoyd