Looking for genset-related wisdom

[OD_Animal]

Recently had two gensets thrown into my lap with instructions to return at least one of them to a somewhat servicable condition.
I am unfamilair with this particular type of genset. From what I can tell its a 28vdc air-cooled generator used for powering
airframes that this place doesnt have anymore. They've been left out under the elements and forgotten until a task
came up where it is suddenly paramount to my many bosses that I make at least one of the two units at hand function.
I've attached pictures and have already downloaded a copy of the operators TM listed on the data tag, along with the organizational level maintence manual.
But from personal experience I have learned that even with a manual, nothing can improve the chances of a dubious project like solid experience.

The current status:

-its been sitting for at least 5 years outdoors with no cover and with gasoline
sitting in the fuel lines and most likely the carburator. Flushed tank but having issues with fuel pump to try and flush the rest of the lines.
Im working on extracting the carb and stripping it down, since the fuel tank smelled more like varnish than gasoline.

-Stole a battery out of one of our unused airframes and tested the electrical systems as far as i can without starting the engine, switches work,
and power appears to be getting to all parts of the system. But when the Run switch is placed in the 'start' position the DC motor just makes a
quiet click and then a whirring noise but does not turn like its not getting enough current.

-the magneto is generating a very healthy spark (tested on accident when a curious associate cranked the handle while i was workin on one of the leads)

I am not a generator maestro, and am open to any advice whatsoever about this. If any more information would be helpful just let me know.

 

[Timberdeuce]

Good Luck Bro!

 

[OD_Animal]

Thanks bro,

I know how to deal with the engine portion... but have no idea what I'm doing when it comes to the generator unit itself.
It makes noise and hums when power is applied, which makes me think the circuit is complete, but perhaps very weak.
So I think something is dirty and perhaps cleaning it will improve it... but I have no idea what to clean or where I need to look.
Hoping someone on here has some ideas, even if their experience isnt with this paricular type of generator unit.

 

[jbk]

i dont know anything about this set, but have seen them come up for auction, nice motors. 7.5 kw 28 volt dc. their should be some output lugs somwhere. i guess you could see if its making correct voltage. maybe someone off grid might have a use. lots of dc amps.

 

[brianrbull]

Have you had the engine running yet? That looks like a 4 cylinder 65 horse Wisconsin air cooled. Good engines.... as to the Gen portion I would start the engine and see what happens.... and take it from there.

 

[deuceaid]

I would check the brushes and comutator, the brushes could be worn down, or be frozen in place ( maybe weak or broken springs).

 

[319]

Take the starter motor off and bench test it. It may just be stuck.

 

[OD_Animal]

Take the starter motor off and bench test it. It may just be stuck.

Could you please tell me what Id need to make an improvised bench tester?
What readings I would be looking for while performing the bench test?
The bosses have me workin far from my realm of expertise, and effectively
without support or specialized tools (aside from what i can rig up myself).

 

[319]

Could you please tell me what Id need to make an improvised bench tester?
What readings I would be looking for while performing the bench test?
The bosses have me workin far from my realm of expertise, and effectively
without support or specialized tools (aside from what i can rig up myself).

Is the starter motor 12 V or 24V and what voltage battery did you use? Was it fully charged?
Remove it, clamp it in a bench vise and apply power to it. If it spins under power then your engine has issues. If not then you need to either repair or replace the starter motor.

 

[deuceaid]

I notice there is a hand crank on the motor,,, ( I would never try using it) but does the motor freely spin with the hand crank (by freely I mean its going to be hard, but not rusted in place)

 

[coyote62ny]

you can hand crank that engine if the timing is right and you have spark and gas give it 1/4 turns of the crank starting at the bottom and come up with the crank do not wrap your thumb over the handle or it could break your thumb or arm dont ever try to spin an engine with a crank if you have everything right a couple 1/4 turns of the crank and it should start [after you fill the carb with gas] these engines start easy when they are set right make shure your timing is correct you can look that up at wisconsinengines.com

 

[OD_Coyote]

Its got wheels, have you tried push starting it son?

 

[OD_Animal]

319- The starter motor is a 28v DC generator thats attached to the motor via belts, for starting it uses the 24v aircraft
battery to use generator as a motor in order to crank the engine. the darn thing weighs a good 30 to 40 lbs, and
when I attempt to apply power without the belts attached it still wont move, but makes noise like its getting voltage
but just not enough. The battery I used was partially discharged and I currently have it in the avionics shop
being reconditioned, just in case it is the culprit.

deuceaid- With plugs out the whole engine spins like a dream on via handcrank, no rough spots or any
indications that there are any 'sticky' spots.

coyote62ny- Thanks for the warning about busting my arm up with the crank handle. the attachment splines for
the handle are slanted so it looks like it should slide off as soon as the engine is going faster than i can turn it.
But if she takes off with a kick I definately dont wanna have my arm still attached.
Thanks for the link to the engines site, ill need that after i get the carburator 'de-varnished' and figure out whats
wrong with the fuel pump.

OD_Coyote- I pushed the genset around with a tug for almost 2 hours in the desert heat, and I really thought it
was gonna catch and fire a few times. I was so close. but the guy I had riding on it to 'pop the clutch' couldnt
seem to locate any pedals.
We are going to install some pedals along with a spoiler... just to improve its corning at high speeds, which the manual
says is suspect. Hopefully just going faster while pushstarting will negate the
need for a clutch?

Thank you gents for your advice thus far (even OD's), and hopefully between the lot of us we can get this neglected
piece of machinery living again. Found out today its going to be used to place 8 UH-60s painted in MFO orange and white
into the back of a number of C-17s. Not the old OD iron we all love, but still going to be some cool pictures nontheless.

 

[deuceaid]

A few more things, always keep in mind if it backfires ( while hand cranking ).
Another thing You could do, if you cant get the starter going right away but need it in a pinch, find a large 1/2 inch drill, and cut/weld/snap together some kind of rod to chuck into the drill and mate it with the hand start socket. And if it turns in the right direction, you could put a nut in the drill chuck and a bolt threaded into the nut ,as a backup that will spin loose once the motorstarts- just incase the socket doesnt pop off like it should.

I have done this on smaller 13 hp motors that I had to get running no matter what. Same thing again, watch out when it starts

 

[OD_Animal]

Tore the rest of fuel system off today from selector valve all the way to carb. Found stuff wrong with everything I pulled off today,
so hopefully the cumulative efforts of all these little problems is why the fuel system was inop.
Everything from gaskets being torn or missing, to tan CARC paint being all gummed up in the carburator and then protected in varnished stale gas.

Strainer unit was a combo of varnish, tan paint, and gasket not installed.

The fuel pump was full of paint, but once cleaned functions just fine and all the gaskets were reusable.

Tore the carb apart and let it soak for an hour and then individually sprayed cleaner through each jet, valve, and port.
The gasket on it was ripped my guess it that the previous installer was apparently oblivious to the fact that you can easily remove the float hinge pin and they tried stretching it around the floats to install. We all know how well that normally works out. scrounged up some gasket material and knocked out a new one. Threw it back together but have yet to reinstall it.

The generator unit is still being cleaned, but once the fuel system is together, and magneto timing is confirmed, I will probably reinstall it and run the engine just so I can put a multimeter to it.

 

[OD_Animal]

Found something while reinstalling fuel pump what wasnt explained in the manuals. I was wondering if anyone knows what this little thing is. It appears to be springloaded and threaded like it was hooked to something originally, it is mounted to the engine and attached in the same bulge that the fuel pump bolts to. Is this some sort of fuel shutoff? Or is it something that I can just leave alone and not have to worry about? Little levers that arent connected to things make me nervous.

 

[liftman]

Looks like the fuel pump manual primer lever. Should operate the fuel pump when moved.

 

[OD_Animal]

Threw it all back together.
Generator unit was cleaned and reassembled. When power is applied, it now produces a scary amount of torque at a fair RPM,
definately enough to crank over the little gas engine with ease. Cranked it over and verified that the magneto was firing properly,
then jumped the gun and tossed a cap of gas into the intake and let 'er rip.
Looks like everything is golden except for fuel, she purrs like a kitten but only as long as I keep feeding fuel through the intake.
No air in fuel lines, and I verified that fuel is indeed getting through the pump and filter to the carb.

Any suggestions?

 

[deuceaid]

maybe the fuel jet is plugged with carc orsomething, Have you put the straw that comes on a can of wd40 on one end of the jet and sprayed thru it, and seen it come out the other end? and it getting to the carb,,, but is the bowl filling up?

 

[PeterD]

Like Deuceaid says, check those tiny passages (jets) on the carb. The photos show a lot of 'crap' there, I'll bet they are clogged.