Info/Advice on Kohler 12.5 KW Diesel Generator Repair/Modification

[oldmansax]

The '82 Bluebird Wanderlodge I just bought has the original equipment Kohler 12.5 KW generator on a slide out tray in the front. It has  a 4 cylinder Perkins diesel. The hour meter shows 2206 hours. The engine operates perfectly.

Before I ask all the questions, I know I should have provided you all with the model number & I can look some of this stuff up on the 'net but I am hoping somebody here has some first hand experience with one of these & also, I'm lazy! 

First, the unit will not produce any electricity. It produced fine setting still at first & then quit. I had the Onan tech look at it in Florida & he said it needs a new voltage regulator, which I bought ($311) and then he said the stator was bad also (big job, part cost over $1000).

Second, it sounds like it is turning 3600 RPM when running although the generator is a 4 pole model. It is my understanding that 2 pole models turn 3600 & 4 pole models turn 1800. Anyone know for sure?

If it IS turning 3600 RPM I need to modify it for 1800 RPM as it is way too loud! I can't hear anything but the generator while driving. If it is turning 1800 now, all questions are moot because I will have to replace the entire unit somehow.

QUESTIONS:

Was it originally 3600 RPM?

If I fix the original generator head, can it be modified to turn 1800 RPM?

Can I just install a new head, something like this:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230515437896&ssPageName=STRK:MEWAX:IT


How do I check the RPMs on the Perkins? It has no tach.

The engine looks like the same one we used on the old Thermoking ND30. If so, it had 52 HP. Why would anyone use a 52 HP engine on a unit that should require only 15 to 20? I am not asking for mind reading, just is there a known reason for over spec engine.

Is the entire unit worth anything as is?

Any other helpful comments?

I know I should just by a new generator but there is no money to do that now so there is no need to point that out. I already know I have no money! 

Thanks!

TOM

[junkman42]

Tom, If the perkins is a 4-107 or 4-108 it will not turn 3600 rpm.  That series of engines is really about 40 hp and are very common in old sailboats.  The 107 has wet sleeves and the 108 dry sleeves!  At 2 hp per kw it is not really much overkill.  I have overhauled many of these engines and they easily run 10,000 hrs in commerical service on generators on oil rigs etc.  My guess is once repaired the genny will out last most of us!  God luck John L

[luvrbus]

Tom, www.vintagebirds.com those guys know every nut and bolt on the older birds


good luck

[oldmansax]

John, are you saying it is probably turning 1800? If so, I am going to have to get another generator as this one is entirely too loud.

Luvrbus, I belong to the Wanderlodge forums and, while I like those guys, this forum is way more mechanically inclined. I searched Vintagebirds for info already with no luck.

Still looking for answers.......



TOM

[thomasinnv]

this be the reason i chose a gas generator.  i looked around quite a bit before i bought my last one (4th generator i've installed in 4th rv in 3 years) and it seems the diesels are just noisier.  not to mention they cost quite a bit more for the same size.  i was not willing to live with the extra noise because we boon dock a lot.  it would also take a long time for me to return the investment for the added cost of the diesel set compared to the added fuel efficiency of the diesel.  i would rather have the long life and dependability and fuel efficiency of the diesel, but not the added noise.

[rwc]

I thought water cooled diesel generators running at 1800rpm were supposed to quieter than gas models running 3600rpm

[junkman42]

Tom, I apologize, I for some reason think people can read My mind.  I was trying to imply that perhaps the governor is not operating properly which in the case of the perkins is possibly a function in the injection pump.  It is possible the engine is running balls to the wall which I would presume could cause the regulator to remove excitation from the field causing no output!  If the engine is from the series I mentioned it is a direct inject injection diesel which by nature is a rattling sob!  Newer engines in many cases are indirect injection or electronic controlled direct injection which are much quieter!  Hope You get it ironed out!  Regards John L

[luvrbus]

Tom, most of the older BB with the 12.5 had a Murphy controller check the Murphy sites and see if yours has a panel like one of their models they were equipped with a overspeed protection.
You can also buy a hand held tach from www.calright.com they have a wide selection of prices, those are good units I would not remove it you will find it to be something simple but if the Murphy controller is bad that is a 600 dollar item

good luck

[oldmansax]

Tom, I apologize, I for some reason think people can read My mind. 

Don't worry about it! I have the same problem.  LOL. I had a guy tell me one time he COULD read my mind but he hated to wander around in there!

but if the Murphy controller is bad that is a 600 dollar item

That's good info and why I am weighing my options. I already know the stator is bad. I had one guy say it could be $1000. I don't think I want to spend lots of money on this if there is a better solution.

TOM

[James77MCI8]

If it is a four pole generator, it should be running 1800 RPM's. If it is running faster than that the over speed circuit will remove the excitation voltage and you will have no output. Any shop that is familiar with the Perkins can check the rpm for you.

[TomC]

Put a hertz meter on it and see if it is producing around 60hz (this is how you set the speed on the governor).  It is a 1800rpm engine.  Although the Perkins is a good engine, I don't know if they are made anymore.  Personally, I'd see about repairing what you have.  If it is noisy, there are multiple ways of silencing it down.  Good Luck, TomC

[fe2_o3]

Kohler 12.5 Diesel Generator in Wanderlodge    Does it sound like this?...Cable

[Skykingrob]

Tom
If it is a model 12.5CCO, I have a manual I could copy and send to you, if you don't already have one. According to my manual the 12.5CCO uses a Yanmar engine, so it may not be the same model. My manual list a troublshooting suggestions for your problem:
circuit breaker in off position
no dc power to the controller
fuse blown in the end bracket or junction box
generator malfunction due to sticking brushes, broken brush heads, blown stator
lack of generator excitation
All of the above can be checked by yourself (which I am sure you ahve already done) but the manual does not answer how to repair the last two. I have seen answers on this forum how to resolve the last one by flashing the generator, so you might want to check the archives.
Hope that helps somehow.

Rob
91 Prevost LeMirage XL40
Missouri

[oldmansax]

Clarifications on my generator problems.

The engine runs fine. It is definitely a 4 cylinder Perkins.

It was producing electricity but quit. The Onan tech got info from the factory and diagnosed both the voltage regulator and the stator as failed. I have the new voltage regulator but have not researched the stator. Tech said it could cost $1000. Onan in Charlotte NC said it may be as little as $100. I have to disassemble to fine out what is in it.

The entire unit has 2200 hours on it.

My main concern are cost to repair vs. compatibility with my use of the bus. I dry camp in lots of places that will not allow the noise level the unit produces now. If I repair what is there, I will have to mitigate the noise level. If the cost  of the repair + the noise mitigation equals or surpasses the cost of a new(er) generator, I might as well take advantage of the situation & upgrade.

Cable, thanks for the video. That is what it sounds like except LOUDER!

I am going to have to shelve this project for the next few days as I need to do some hurricane prep.      I am 3 feet above sea level & whatever Earl does will affect me.

TOM