# Rust bucket generator restore (Picture heavy)



## OrlyP (Oct 19, 2021)

Just putting this on here. I'm sure not everyone is into restoring old relics. Neither am I... or so I thought. When I started this 6 weeks ago, I thought of giving up a few times. I mean, if the stench of decades-old gas not leaving your skin for days on end doesn't do it, just thinking about the amount of rust to clear probably will. 

This has been a basket of many firsts for me. Anyway, I'll keep the commentary to a minimum.... sit back and enjoy my feeble attempts.

The generator is a Denyo GA-3600; 3.6kW Peak, 3.2kW Running. It's a brushless generator that uses the lighting coil in the the engine as the exciter for the stator. It's not a "capacitor-type brushless" as I originally thought it was.

This is the state it was in when I started on it. It was left outside in the sun and rain for years, stored 'wet', and left for dead some 25 years ago.... by me. So I owe it some sort of makeover.

















































Stripping it down to the bones...

















Wirewheel and sanding...









Rust converter









De-rusting the bolts and screws as well as applying some organizational magic









Started painting stuff.... everything has primer, base coat, and clear coat









































The ship has sailed on the silk-screened panels. All I can do was clean the surfaces as best I can without further damaging the original paint and gave them a couple layers of clear coat









Finally, the engine and powerhead went through several power wash and degreasing process before finally being blow-dried and mated again with the frame










The final results... (except for the tank):









































Running like a champ.... dirty electricity and all.


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## GenKnot (Dec 20, 2021)

Very nice!

Most people would have just tossed that after one look as they would have thought it to be hopeless.


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## OrlyP (Oct 19, 2021)

GenKnot said:


> Most people would have just tossed that after one look as they would have thought it to be hopeless.


Almost considered it. In the end though, I realized it was worth more to me running than its value in scrap. I also get to learn a lot along the way.

Most are still the original parts and only the following were replaced:
1. Carb - The old one is hopelessly clogged with varnish as hard as epoxy
2. Engine dampers
3. Ignition switch
4. Fuel lines
5. Gasket kit
6. Governor springs
7. Muffler (bought 2nd hand)
8. Voltmeter

Moving forward, I will just have to focus on the gas tank. I still need to remove old varnish and some surface rust inside then sand and repaint the outside. Otherwise, this generator is done.


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## GenKnot (Dec 20, 2021)

OrlyP said:


> I still need to remove old varnish and some surface rust inside then sand and repaint the outside.


I have heard that POR 15 makes some good products to address gas tank issues, but they may not be available to you. Acetone would be my 2nd choice to attack the varnish. Also, throw a couple of handfuls of rounded pebbles in the tank to act as scrubbers as you shake the tank around.


Amazon.com : POR 15 Marine Clean


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## Dutchy491 (Sep 18, 2019)

OrlyP said:


> Almost considered it. In the end though, I realized it was worth more to me running than its value in scrap. I also get to learn a lot along the way.
> 
> Most are still the original parts and only the following were replaced:
> 1. Carb - The old one is hopelessly clogged with varnish as hard as epoxy
> ...


A labour of love that is….!!


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## motormonkey (Jul 10, 2016)

Pour some gravel (crushed stone with sharp abrasive edges) in the tank, strap it to the wheel of a riding lawnmower, and take it for a ride around the yard for a few minutes. The inside of the tank will be shiny like new.

BTW, given that the entire fuel system was toast, that genny would have been a good candidate for an LP or natural gas conversion.


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## kairus00 (Sep 9, 2021)

That looked like a really fun project. I'm jealous!


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## aandpdan (Oct 8, 2012)

Nice job! I'm sure you'll get many years of use out of it!


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## OrlyP (Oct 19, 2021)

GenKnot said:


> I have heard that POR 15 makes some good products to address gas tank issues, but they may not be available to you. Acetone would be my 2nd choice to attack the varnish. Also, throw a couple of handfuls of rounded pebbles in the tank to act as scrubbers as you shake the tank around.
> 
> 
> Amazon.com : POR 15 Marine Clean


I can get them if I wanted to, but unfortunately it's going to overshoot the budget quite a bit. I will have to get by removing as much crud inside and leave well enough alone. I added a B&S red fuel filter to stop debris from messing with the carb.



Dutchy491 said:


> A labour of love that is….!!


Lol... there were cussing and expletives thrown around when a bolt or nut won't come off. We were a proper couple for little over a month.



motormonkey said:


> Pour some gravel (crushed stone with sharp abrasive edges) in the tank, strap it to the wheel of a riding lawnmower, and take it for a ride around the yard for a few minutes. The inside of the tank will be shiny like new.
> 
> BTW, given that the entire fuel system was toast, that genny would have been a good candidate for an LP or natural gas conversion.


I have a bottle of acetone to get most of the varnish out and likely give it a 2nd acid bath to clear the rust. It will be properly neutralized this time, that which I failed to do before so flash rust came back in a matter of minutes. I am a fast learner, though. lol

I did consider doing a fuel conversion but I soon found out that this engine does not have an aftermarket bi/tri-fuel kit. Although, permanently converting the old carb for LP-only is a possibility that seems worth considering.



kairus00 said:


> That looked like a really fun project. I'm jealous!


It was! I could've likely finished it in a week or two, but I also need to take care of less important stuff... You know, work, family, kids. lol



aandpdan said:


> Nice job! I'm sure you'll get many years of use out of it!


I think so too. Setting this up as a backup to my main gen. The engine is very reliable and are commonly used here in construction. Parts are also widely available. Though, the power head is a different story. If it dies, that'll likely be the end.


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## OrlyP (Oct 19, 2021)

Let's rewind a bit to the time prior to starting the engine.

The oil inside was particularly black, thick and a little low. I drained it all out as much as I can. But instead of using new oil, I poured in the old oil from my other generator just to help agitate the crankcase and dilute the really old 90's oil. I heard that Diesel _fuel_ is a good engine flush... good solvent properties and still slippery enough to offer short-term protection. Do you guys recommend using Diesel fuel as engine flush?

Here's the plan...

1. Drain the oil and pour in Diesel fuel up to the full mark
2. Run the engine at idle (1800 RPM) for 3-5 minutes
3. Drain the Diesel fuel
4. Add fresh oil to the full mark, run for 5-10 minutes
5. Replace the oil one final time to flush out the Diesel


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## Dutchy491 (Sep 18, 2019)

I’d flush diesel through the engine but without running it. Maybe even let the diesel sit overnight soaking the internals? Just pull the recoil several times, but carefully with the spark plug removed. I don’t think there’s enough lubrication to run the engine with just diesel fuel in the crankcase. Then drain that and run the used oil for a few minutes and drain that before a fresh and quick new oil change… Awesome progress, nonetheless 👍


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## iowagold (Jan 22, 2020)

wow that is an old dog.


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## OrlyP (Oct 19, 2021)

I don't get why many small engine mechanics still prefer L-heads/flat-heads over OHV. They say that the former is simpler. I feel it should be the opposite.

Anyway, I noticed that this Robin engine was a little hard to pull-start and I had to feather the recoil to get it past a certain point in the compression cycle so I don't break the recoil or my arm. Compression is 120 psi... which should've been just around 85 PSI or lower (@ <400 RPM). Well, I discovered that the tappet clearances on both valves were a little loose at 0.13 (Standard is: 0.10 ±0.02).... probably why the compression release wasn't working.

Apparently, you can only correct the clearances by grinding off the valve stems if the gap is too tight, but once it becomes too loose (valve stem has become shorter), the only recourse is to replace them? Seems like a waste.

On the other hand, OHV valves can be adjusted almost infinitely because of the adjustment screw. You can practically use the valves down to their stumps. lol


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## McCorby (Apr 26, 2021)

OrlyP said:


> Apparently, you can only correct the clearances by grinding off the valve stems if the gap is too tight, but once it becomes too loose (valve stem has become shorter), the only recourse is to replace them? Seems like a waste.


If you have access to a valve seat cutter, you can recut the seats to reduce the tappet clearance.

Also, you’re only .01 out of spec. That should not greatly effect the operation of the compression release.


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## OrlyP (Oct 19, 2021)

McCorby said:


> If you have access to a valve seat cutter, you can recut the seats to reduce the tappet clearance.


Is this somewhat the same as lapping or totally different?

EDIT:
Ok, different tool. I don't have it, unfortunately.

But this does bring credence to my point.


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## McCorby (Apr 26, 2021)

Is the measurement and specs you gave in mm or is it inches and you’re off a decimal?


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## OrlyP (Oct 19, 2021)

McCorby said:


> Is the measurement and specs you gave in mm?


Yepp. Everything is in Metric.



> TAPPET ADJUSTMENT
> Lower the tappet all the way down, push the valve, and insert a feeler gauge between the valve and tappet stem to measure the clearance.
> 
> NOTE: The correct tappet clearance for both intake and exhaust valves is 0.1 mm ± 0.02 mm as measured when the engine is cold.
> ...





McCorby said:


> Also, you’re only .01 out of spec. That should not greatly effect the operation of the compression release.


Come to think of it, 0.13mm was still a little loose. My feeler gauge oddly didn't have anything above 0.13mm and just jumps over to 0.25mm.

It still runs like new but can be hard to pull-start, especially if the engine is already hot. I think that's about as much tolerance that is needed to affect the compression release.


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## McCorby (Apr 26, 2021)

The lift created by the release should be much greater than the .01mm out of spec you’re at. While not knowing the compression release lift spec of your engine, and assuming it’s a mechanical compression release, I’m guessing it’s at least 1mm lift.


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## OrlyP (Oct 19, 2021)

You may be right. But I guess I'm just afraid what the likely alternate reason would be.... a stuck compression release mechanism.


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## iowagold (Jan 22, 2020)

or broken compression release mechanism.


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## OrlyP (Oct 19, 2021)

Finally got around cleaning and painting the gas tank. 

The tank started off absolutely nasty and I had half a mind to throw it out but then I realized I'd be shooting myself in the foot as they don't make these no more. Anyway, this little guy went through a vinegar, muriatic acid, and acetone bath. There's no hope of getting the inside back to pristine condition without spending way above its worth, but at least I got most of the varnish chunks out. Last thing I need is a solid gunk clogging the fuel lines. 

The gen does have a sediment bowl and I've installed a red B&S fuel filter. I hope they're enough to protect the carb. Though I feel I may need to drop the carb bowl and clean it after running it for a few hours at least.

Not for the faint of heart...
































Checked it for leaks and ran it for several minutes. 

It's now complete...


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## iowagold (Jan 22, 2020)

looks pretty now


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## OrlyP (Oct 19, 2021)

What can I say.... if you try really hard enough, you can indeed polish a turd. lol


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## iowagold (Jan 22, 2020)

I do that all day long! LOL!
you might be able to make a vynal decal for the control panel to fresh up the look there as well...
then it would look close to new!


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## OrlyP (Oct 19, 2021)

A bit of a PSA while testing out a cheap Carbon Monoxide (CO) detector

Don't try this at home.

Not the most scientific method but this helps illustrate how fast CO from a generator can accumulate in an enclosed or semi-enclosed area. This is part of our garage with one side open. Even so, with the generator running at operating RPM (~3600 RPM), it can fill the area with poisonous CO gases in a matter of seconds. At low RPMs, it's not producing as much CO and it was able to safely dissipate outside.

CO is an odorless and colorless gas by-product of combustion and can be lethal to people and animals. Never operate your generator near living spaces or in areas where there's a possibility that combustion gasses can pool up and get to any person or pet. Remember: Proximity and airflow.


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## iowagold (Jan 22, 2020)

well you took one for the team!
even in an open porch you can get some bad numbers.
remember that stuff is heavy...
so an inversion table is a good idea!!
hang like a bat for a bit.
and o2 is handy to have around if you are old like me!

but for most a good 48 inch air mover fan when operating to move the air around when working on this equipment.


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## OrlyP (Oct 19, 2021)

^ Ah, you noticed how I fumbled about looking for the throttle lever to pull it back to idle?

Trace amounts of CO messing with my fine motor skills. hahaha

Seriously, that stuff is bad for you.


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## iowagold (Jan 22, 2020)

yup nasty stuff at best!
if it was a diesel it is even worse on the exhaust trash..
that stuff is hard on a person who does service work!

hey they now make cats for small engines!
search blue cat...
the run 300-600 bucks...
but the fumes are way lower...
same when on LP or NG the numbers are lower in the count per hour.

try the test with a night hawk if you can find one.


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## OrlyP (Oct 19, 2021)

I was ready to close the book on this but apparently, this rust bucket is a gift that keeps on giving.

So today, I decided to put it through its paces and ran a small air conditioner as a load. 15-20 minutes in, the engine started to run funny and eventually stalled out. It was a head-scratcher since it started right up after that. But about a minute later, the same thing happened. Taking off the gas cap to see if I've run out of fuel, I can see bubbles in the tank coming up from the fuel line. Vapor lock.

The old fuel line had a split corrugated loom wrapped around it. I thought it was just an anti-abrasion thing but it probably works as a thermal insulator too. The hot air from the engine flows over the fuel line by design so that's probably why it's happening. Time to look for a loom.


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## GenKnot (Dec 20, 2021)

OrlyP said:


> The old fuel line had a split corrugated loom wrapped around it. I thought it was just an anti-abrasion thing but it probably works as a thermal insulator too. The hot air from the engine flows over the fuel line by design so that's probably why it's happening. Time to look for a loom.


Maybe you could fabricate a sheet metal shield for it. That might last longer. Just a thought...


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## OrlyP (Oct 19, 2021)

GenKnot said:


> Maybe you could fabricate a sheet metal shield for it. That might last longer. Just a thought...


That's Plan B if adding an insulator doesn't fix it.


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## OrlyP (Oct 19, 2021)

Last and final update (one hopes)...

This was the BEFORE shot. The hot air from the engine heats up the fuel line causing it to vapor lock.









To solve the vapor lock issue, I was contemplating between using a loom insulation around the fuel line or as @GenKnot suggested, use a piece of sheet metal as a heat shield.

I did both.

I covered most of the fuel lines with automotive loom and hacked a sheet metal cover I stole from an old PC power supply.


















What I basically did was deflect the hot air from the engine 90 degrees to the side. Now tell me if that doesn't look OEM to you . I was meaning to paint it but, I think that'll do for now.


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## ToniAv (2 mo ago)

Hello. Have you removed the motor back cover? Interested in how the wires are connected and whether there is a Voltage Regulator. And in what position do you leave the throttle. I got such a generator as a gift and I can't normally make it work.


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## OrlyP (Oct 19, 2021)

ToniAv said:


> Hello. Have you removed the motor back cover? Interested in how the wires are connected and whether there is a Voltage Regulator. And in what position do you leave the throttle. I got such a generator as a gift and I can't normally make it work.


This is actually unlike many of the more common brushless generators. First of all, the field winding is powered by an excitation coil under the engine flywheel. It does NOT have a capacitor.

I have been unable to open the back end cover on the stator, partly because it’s stuck, but mostly because there’s nothing in there but the windings themselves. The generator head has 6 wires coming out of it... there are two 110V legs, each with its own Hot and Neutral wires, and the 2 wires for the field winding.

The exciter coil in the engine goes to a full-wave rectifier inside the control box. The DC output from the rectifier goes to the field windings (polarity-sensitive).

The main stator windings (4 wires) also goes to the control box where they are broken down to 110V and 220V receptacles.

I am willing to provide more information if you have specific questions.


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## OrlyP (Oct 19, 2021)

Here's the wiring diagram. There were a few variations of this model with minor wiring and feature changes.

The one I have has the following distinctions:

1. It did not came with the Charging Coil (CC) along with the accompanying 12V DC output terminals
2. It came wired with both 110V and 220V output but I have modified it to only produce 220V, by following the schematic and bridging wires V1 and U2.


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## GenKnot (Dec 20, 2021)

Considering where he's located, he's probably very desperate to get that generator running.


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## OrlyP (Oct 19, 2021)

GenKnot said:


> Considering where he's located, he's probably very desperate to get that generator running.


Yup, I realize that. He also reached out to me on YouTube about a month ago. His latest followup was just within the last 10 hours.


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## ToniAv (2 mo ago)

Good afternoon. I understood about the electrical circuit and that it is necessary to keep the engine at 3600 rpm. I will try, thank you very much, have a nice day.


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## Colt Carson (6 mo ago)

I was hoping to see an "after" of the interior of the fuel tank…


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## OrlyP (Oct 19, 2021)

Colt Carson said:


> I was hoping to see an "after" of the interior of the fuel tank…


I'd say I got over 90% of the crud out with the muriatic acid and vinegar baths, but without access to Evaporust or similar products, I found it impossible or impractical to clean it any better.

However, since the time it's been put back into service 6 months ago, there had been no rust re-forming and whatever grime is in there now, is stuck in there and doesn't seem to mix with the gas. If and when bits and chunks do somehow get into the fuel line, it will likely just collect in the sediment bowl below the petcock and anything that's suspended in the fuel will be caught by the red inline filter I added.

Right now it's got a few liters of non-ethanol fuel and you can visually see through it right to the bottom.




























Just a reminder that not too long ago, this is what it looked like... a mess of varnish and tar-like substance coating the inside.


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