Anybody had any experience with military generators?

oldmansax · September 19, 2010, 06:53:22 PM

I am thinking about the Kohler 12.5 diesel generator in my Wanderlodge. It has the Perkins 4 cylinder engine that is really noisy. I have pretty much found out I need to spend several hundred dollars on it & I am not sure I want to do that.

Has anyone had any experience with the military surplus air cooled diesels? I have looked online at some of the 10KW & they look promising. 1800 RPM. Low hours. I am wondering about the noise level.

Any real life experiences? Opinions? Comments?

TOM

robertglines1 · September 19, 2010, 07:05:27 PM

biggest problem you will have is the military has special specifications they have their equipment built to so sometimes parts are hard to come by..been there Bob

TomC · September 19, 2010, 08:51:03 PM

If the air cooled military generator is based on an Onan 4 cylinder (big square housing on the front with the round fan cut out), stand back and get your ear plugs. You think your Perkins is noisy? Wait till you here the racket that air cooled 4 cylinder puts out. I know, I have the 2 cylinder version called a DJB with vacu-cooling-so the hot air is pushed out of the cabinet. I made a 3/4" wood cabinet on a 1/4" steel base with foam lead insulation (standby power at the house). It quieted it down alot, but you can still hear it 100ft away. Way to noisy, way to much vibration.
Get your Perkins fixed! Good Luck, TomC

akroyaleagle · September 20, 2010, 08:15:51 AM

Having spent 24 years in the Army and some around it since I got out, I can tell you the biggest maintenance headache I ever encountered was military generators.

They work fine when they work. They did not work very much of the time.

They are, as previously posted, NOISY!

oldmansax · September 20, 2010, 09:11:49 AM

Well.... I guess I"ll scratch that idea!!

TOM

gus · September 20, 2010, 02:44:52 PM

I assume your Perkins is liquid cooled. If so, you will never be satisfied with an air cooled one.

The noisiest and shakiest thing I ever owned was my Onan 2cyl air cooled 6.5KW. It was so bad and parts got so expensive that I gave it away and got a Honda 6010 liquid cooled 2 cyl gas and have never been happier. Unfortunately that is the largest Honda makes as far as I know but plenty for me.

oldmansax · September 20, 2010, 06:23:11 PM

Yep, the Perkins is liquid cooled. But, it is the LOUD. I can't heat the 6V92 running at all while driving if the generator is running. It appears to be a problem in all the early Bluebirds because everybody who has one complains. There is some amount of mitigation that can be done but nobody has made them acceptably quiet so far.

The other reason I would like to replace it is I really don't need a 12.5 KW generator. I have a 6.5 now & it does OK. I would like an 8 or 10. I am thinking about fuel consumption here.....

The engine runs perfectly but the stator in the generator is bad. I have been quoted $1000 for the part alone & I just don't want to spend that on something I think I will be unhappy with anyway.

BUT, I don't have $8K or $10K to spend on a new one either. I did have an offer of a mostly rebuilt 12.5 KW generator head but it is in pieces and the pics look like it may be either older or newer than mine. Mine is rectangular & that one is octagonal.

Still thinking......

TOM

robertglines1 · September 20, 2010, 06:59:16 PM

Tom ,ck your local generator dealer..I found a tradein with 34 hrs on it for 1500--it's a 7.5 cabinet and all-was to small for previous owner.

artvonne · September 20, 2010, 07:44:17 PM

What kind of shape is the Perkins in? Valves adjusted? Injectors cleaned and checked? Timing checked? I'm sure you know, but diesels can be extra noisy if they are out of tune. Probably the biggest issue is whether its an 1800 rpm generator, or 3600 rpm. A 3600 rpm gen wont be quiet even if you mount it in someone elses rig and put them on the other side of the campground, no matter the engine. If its not an 1800 rpm gen, give up now and go find one.

How is it mounted? Can it be mounted better/different? Are the current mounts old and solidified? How is it insulated, and can it be better insulated? is everything on it and around it secure? Those buggers can rattle, and anything loose on it or near it will rattle along with it.

I have a 3 cyl Kubota 6.5 KW generator made by Onan. Not a good comparison I suppose, but I find it pretty quiet. I had a 4-108 Perkins 4 cyl in a skid loader, I thought it was as quiet as any other skid loader when wound up to nearly 4000 rpm. Throttled back it wasnt loud at all. Certainly not as loud as the Case I own today with a simular size Cummins. That SOB is LOUD!

oldmansax · September 21, 2010, 04:42:16 AM

Quote from: artvonne on September 20, 2010, 07:44:17 PM
What kind of shape is the Perkins in? Valves adjusted? Injectors cleaned and checked? Timing checked? I'm sure you know, but diesels can be extra noisy if they are out of tune. Probably the biggest issue is whether its an 1800 rpm generator, or 3600 rpm. A 3600 rpm gen wont be quiet even if you mount it in someone elses rig and put them on the other side of the campground, no matter the engine. If its not an 1800 rpm gen, give up now and go find one.

How is it mounted? Can it be mounted better/different? Are the current mounts old and solidified? How is it insulated, and can it be better insulated? is everything on it and around it secure? Those buggers can rattle, and anything loose on it or near it will rattle along with it.

I have a 3 cyl Kubota 6.5 KW generator made by Onan. Not a good comparison I suppose, but I find it pretty quiet. I had a 4-108 Perkins 4 cyl in a skid loader, I thought it was as quiet as any other skid loader when wound up to nearly 4000 rpm. Throttled back it wasnt loud at all. Certainly not as loud as the Case I own today with a simular size Cummins. That SOB is LOUD!

It is a 4-108 Perkins and is in good shape. It appears Bluebird owners are quite anal about maintenance. The PO's shop was big enough for 3 buses and still have room to work.

It's 1800 RPM. Mounted on air bags. The enclosure could be better insulated. I have some Auralex foam on the way to take care of that. The radiator is remote mounted on the drivers side.

Like I said, it's loud to me now & it will be loud based on the threads from the Bluebird Board. And, most of them have way more money to spend on theirs than I have to spend on mine. Some have spent several thousand dollars on fans & enclosures & they are still loud.

TOM

TomC · September 21, 2010, 08:01:58 AM

If the radiator is remote mounted, you should enclose the entire generator compartment tight lined with 1" lead foam insulation. Then to ventilate it, buy a 250cfm inline bathroom ventilator (from Graingers and others) that has an 8" hose. Use the blower to push air into the gen compartment and then another 8" hose at least 8ft long to exhaust it. The long length will dissipate the noise. Be sure to put screens on the ends to keep bugs out. It will make a giant difference in the noise output.

My goal on my truck is to have my generator just about silent running (if you can't hear at 10ft, then it is just about right). Remember-there is no such thing as a too quiet generator. Good Luck, TomC

oldmansax · September 21, 2010, 04:22:33 PM

TomC,

I'm not saying that can't be done but it would be a job. On a PT40, the generator is on a hydraulic slide out in the front, where the doghouse would be on a truck. I could probably completely enclose it but would have to have a lid that opened to check oil, water, etc. All the wires, pipes and controls would have to be made so they would slide with the enclosure. Not to mention the exhaust. Your idea would work, just implementing it would be challenging.

I really would like to start with something quieter if possible.

But, it may not be possible...

TOM