Kohler Generator making unusual noise

[garmstro55]

Generator is a Kohler 8kw diesel generator, 2004 vintage.

Saturday, after running for about 3-4 hours it started making a clanking/rattling noise. I shut it down in less than 15 seconds after the noise started.

On Sunday, I started the genny and there was no noise and it ran normally. I did not have time to try running it under load, however.

I plan on running under load the next time I am at the boat, but what are the possible problems to look for?

 

[C lectric]

Loose connection of the generator to the engine, loose alternator, seawater pump, coolant circulation pump trouble, loose belt drive pulleys, failing bearings.
Lots of other sources .

If no luck then get a mechanics stethoscope, auto parts supply, and use it to help zero into the source or at the least the general area. Just be very careful when examining anything running.

 

[garmstro55]

Went back yesterday with a stethoscope and, of course, it doesn't make the noise anymore. Ran for about 45 minutes under load. Now I am baffled.

 

[Portage_Bay]

I was once haunted by a ghost noise from a generator. It would come and go. Nearly drove me mad trying to identify the source. It turned out to be something loose that would at times rattle against the generator. Not part of or connected to the generator.

 

[Dougcole]

Hey Gary, do you still have your sound shield installed? Maybe it is rattling?

 

[garmstro55]

Hey Gary, do you still have your sound shield installed? Maybe it is rattling?

A Forum Friend, I think his name was Dave or Doug, yeah Doug, once said to remove the sound shield and throw it away. I followed Dave's - I mean Doug's - advice so no sound shield. It did occur to me that something was rattling. I figure the engine wouldn't run normally if there was something wrong with it. Its not likely to fix itself. I will just have to run it and see if it happens again!

 

[Dougcole]

A Forum Friend, I think his name was Dave or Doug, yeah Doug, once said to remove the sound shield and throw it away. I followed Dave's - I mean Doug's - advice so no sound shield. It did occur to me that something was rattling. I figure the engine wouldn't run normally if there was something wrong with it. Its not likely to fix itself. I will just have to run it and see if it happens again!

Nobody likes a smart Alec, Gary. Lol.

Did you leave the frame in place, the part that holds the control board? Maybe it is rattling?

Just a thought.

 

[garmstro55]

I will take a good look at it next time at the boat. I hope that’s the problem.

 

[Lepke]

A plugged or misfiring injector can sound like a rod knock in some engines. Especially 4 cylinder or less.
Sometimes the needle that opens the injector can stick causing the injector to misfire or fire late.

 

[garmstro55]

A plugged or misfiring injector can sound like a rod knock in some engines. Especially 4 cylinder or less.
Sometimes the needle that opens the injector can stick causing the injector to misfire or fire late.

Interesting. It did sound like something internal knocking, but I turned it off so quickly that I didn't really have a chance to open the lazarette and get a better look (listen?) at it. It ran just fine with no noise a few days later.

Question: Is it possible that the needle freed itself? Also, if it recurs, what is the cure? Is there something I can add to the fuel to help?

 

[Lepke]

Every time I have seen this problem, it fixed itself. But if the injectors haven't been rebuilt since 2004 I'd think about it.
The sticking needle is most common in engines that sit for long periods.

 

[garmstro55]

That's good advice for a winter project. I would like to purchase one injector to have as a spare and online prices seem to range from $400 to over $600! Does that seem reasonable? Does anyone have a connection where I might be able to find a rebuilt injector?