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Shibaura S753 Not Running Good

dalmatiangirl61

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Last Subscription Date
07/10/2019
Not sure if exact same, but close enough? Have not had time to fool with it, and its just too hot right now, stuck it in semi trailer last week, its time for me to go. Data tag below

3306 rpm is too high, if injector pump has been inspected and confirmed good, only other thing it could be is governor, I think:shrug:
 

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Duey C

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12/15/2018
Crazy post: Poobah, post #34 in the 3rd and 4th pics, I'm seeing a something on the governor arm that's been bugging me for days.
I sure may be mad (crazy) but is that tab, that's on the long arm that reaches back to the pump's pin with the clip, bent out and down and not at 90 degrees getting in the way of something else to muck up your governor control?
Also: May we see a pic of the shutdown solenoid at the rear of the injection pump?
 

The Grand Pooh-Bah

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Last Subscription Date
07/03/2019
Finaly got around to pulling the timing cover back off. Is the tab in the circle suppose to be at 90 degrees from the rack linkage or closer to 60 degrees like mine. This tab prevents the rack from moving further towards the off or slower speeds.

 

Duey C

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12/15/2018
I would say to bend it up to 90 degrees. I've had a very few for the 103-07's in my hands as replacement parts for the parts dept and don't recall anything special or funny with them.
If your description of the tab is perfect (not being a smart Alex here), you answered your own and my question too. :) ie: you could adjust the throttle lever and get it where you'd like. :)
I'm excited for you to get control back from that engine. IF the solenoid is controlled by the generator, then it depends on what type of controller is handling the solenoid and rack position.
My fingers are crossed for you as I like these engines!
 

dalmatiangirl61

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Last Subscription Date
07/10/2019
If bending that thing will let it travel more, that just might be the problem. Have not been in to mine yet (and hopefully won't need to fool with gov), and although your pics are clear, we are not seeing it in 3D as you are, you will have to make the call on bending it. Hope it fixes your problem!
 

The Grand Pooh-Bah

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Last Subscription Date
07/03/2019


SUCCESS!!!! The engine is no longer over revving!!! Straightening out that tab on the rack linkage solved the problem. YEA!!!!

NEW PROBLEM
:headbang::yikes::headbang:

Before I could get the Laser Photo Tachometer out to check the actual RPM's the generating end started making this screeching/grindy sound. As soon as the sound started the Hz jumped up from 55 to 63Hz. I shut it down and started it up again and it did it again, I let it run a bit longer and it stopped, then started the sound again.

HELP
 

dalmatiangirl61

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Last Subscription Date
07/10/2019
You know this means you probably need to pull the gen out and open it up, either junk between rotor/stator, bad bearings, or junk between brushes? My guess would be bearings.
 

The Grand Pooh-Bah

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Last Subscription Date
07/03/2019
Been playing with it all day.

Starting to believe in poltergeist.

Some times it purrs like a kitten with 240 volts 62 Hz under no load. Then the next time I start it it puts out 356 volts and dies with fault light. Other times it starts out with 240 volts then changes to 350+ volts and starts the screech sound.

Brushes are good. Checked them

 
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AlanR

Registered
Since the generator is belt-driven, I'd guess that the screech is probably the belt slipping - and the reason the belt is slipping AND the voltage is going way high is that the voltage regulator is putting way more field voltage to the brushes/rotor than it should. Check the DC voltage at the brushes and see what you get - if it's LOTS higher during the screech/356v episodes, check the AC voltage between terminals 11 and 22 AT THE REGULATOR - this is the 'sense' voltage, which the regulator is trying to get to 120v. If voltage here measures 178v during your screech episodes, you have a problem with the voltage regulator. If it measures 0v during the episodes, you have a bad connection/wire.

Alan
 

The Grand Pooh-Bah

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Last Subscription Date
07/03/2019
I think I found the problem



I put some new brushes in and cleaned things up. Then I discovered this crack where the brush makes contact with the slip ring. Anyone know if there is an instructional video somewhere on how to replace the slip ring for a Generac?

That manual was not even close to my generator. Generac sent me the manual for my Standby Generator. The only differences I can find between the drawing I linked to and my generator is the wiring at the PSW phase selector switch.
 
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AlanR

Registered
That slip ring crack is not good - but it wouldn't be the cause of your high voltage episodes. Using the wiring diagram you posted, at the VR module, terminals 1 and 2 are the AC power to the regulator from the excitation field, terminals 3 and 4 are the DC to the brushes, and 5 and 6 are the voltage sense terminals - which is where the regulator wants to see 120v, and adjusts the DC to the brushes in an attempt to do so. IF the regulator is NOT seeing voltage at those terminals, it's going to give the most voltage it can to the brushes in an attempt to get the voltage at 5 and 6 to 120v - which could be the cause of your high voltage.

Alan
 

The Grand Pooh-Bah

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07/03/2019
When it runs good (240v AC) I'm getting 18v DC at the brushes, 0+4 wires at the terminal strip.
 
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The Grand Pooh-Bah

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07/03/2019
Finally went out and started the generator again. Hooked meter up to brushes and I was getting 149vDC and it was making the terrible noise again. I shut it down and tried again, still got high voltage again. The fourth time I started it I got 17.3 vDC and 242 vAC at the breaker.

I ran it for 10+ minutes and it ran great. Shut it down and started it back up several times with no issues. Disconnected the battery then reconnected and it is still running 17.3vDC at the brushes and 242 vAC at the breaker.

Seems to be doing the wacky thing when it is cold start, although it is still 90F outside.
 

Birken Vogt

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Shoot us a picture of the voltage regulator. If it is the current standard pins 3 and 5 on the VR should be sensing voltage. If they are poorly connected this might happen. There might also be a voltage adjust rheostat in series with one of these wires doing this. On one of these old sets I think they had a prior generation of VR but don't remember what it looked like.

Finally went out and started the generator again. Hooked meter up to brushes and I was getting 149vDC and it was making the terrible noise again. I shut it down and tried again, still got high voltage again. The fourth time I started it I got 17.3 vDC and 242 vAC at the breaker.

I ran it for 10+ minutes and it ran great. Shut it down and started it back up several times with no issues. Disconnected the battery then reconnected and it is still running 17.3vDC at the brushes and 242 vAC at the breaker.

Seems to be doing the wacky thing when it is cold start, although it is still 90F outside.
 

Birken Vogt

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Forget what I said there. The wires you want are labelled SEN on the aluminum casting. They should be sensing 120 volts. Trace them out and make sure they are OK back to wherever they go. Or try and meter them on the board when the thing is putting out its high voltage.

However, this type of regulator is known for failing in a high voltage condition. Probably just needs replaced.
 

The Grand Pooh-Bah

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07/03/2019
I pulled and checked each connection at the voltage regulator and the main terminal board. Started it up and it ran fine for about 5 minutes then the voltage to the brushes spiked to 149vDC then dropped off and it shut down on its own.

---------- Post added at 07:29:42 PM ---------- Previous post was at 06:51:00 PM ----------

Forget what I said there. The wires you want are labelled SEN on the aluminum casting. They should be sensing 120 volts. Trace them out and make sure they are OK back to wherever they go. Or try and meter them on the board when the thing is putting out its high voltage.

However, this type of regulator is known for failing in a high voltage condition. Probably just needs replaced.
Would the over revving contribute to it going bad?

The sensing wires go to the main breaker, which is where I was testing the AC voltage.
 
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