Kohler 5E - Backfire blew muffler!

Liberty44140

I think technically a backfire in the exhaust is an afterfire? Anyway this winter I cleaned out the choke and adjusted it. I adjusted it too rich as when I started it today it bogged down badly. Immediately I shut it off. Adjusted the choke to lean and re started, was much better but slight hunting. Stopped it again to make another fine adjustment. Went to restart and there was a boom in the muffler that blew the top off of the muffler! WOW! I ordered a new muffler. I'm assuming that that initial start way too rich caused a fuel buildup which made the afterfire, right? Anything that could have been damaged other than the muffler by the afterfire? I now have an understanding of where the choke needs to be but the admiral says that I can install the new muffler but I'm paying a tech for 1 hour to do final choke adjustments and I think she will win that battle

randy56

Ha ha good story.

Handymans342

Another problem I don't have to worry about lol

Liberty44140

So other than replacing the muffler and getting the choke re set right, nothing else to worry about? Plugs were replaced a month ago on the hard. 

Black_Diamond

I would pressure check the coolant system. You can get a tester for free from like Autozone. Plus all the exhaust hose connections. 

Liberty44140

Thanks BD, will do. The coolant pressure tester attaches right on the radiator cap on the 5e, right? Attach and pump?
thinking while I have it I'll do my engines too although they were done last spring when I bought the boat.

Black_Diamond

Yup, goes right on the 'radiator' cap.  16psi if I remember correct.

Jarodjay

I had my 5E Kohler muffler explode this past weekend so I searched this forum and found this 2017 post. I am trying to understand the source of my issue.

Here was my situation. I used the generator for 10mins and it died. I restarted and used for another few minutes and I shut it off (meaning it didn't die). The second time it was running, it sounded like it was running at a higher RPM than normal. We sat and watch fireworks then headed back to the dock. A few minutes after shutting off the boat, the muffler lid blew (sounded like a bomb). 

It puzzles me that the muffler blew so long after it had been used. I will install another muffler, but I don't want to do that until I understand why it blew. It was scary when it blew and could have caused serious damage (to boat and people). We were lucky.
What are your thoughts on how to diagnose?

Liberty44140

Was the generator running when the muffler blew or was this several minutes after you shut down?

Jarodjay

Generator was off for approximately 1.5hrs before it blew.

aero3113

Jarodjay said:

Generator was off for approximately 1.5hrs before it blew.

WoW, that’s crazy!

aero3113

I wonder if fuel vapors were in there and some how ignited? Just strange that it happened 1.5 hours after shutdown.

LaRea

I can't answer your question, but I can offer this:  consider replacing it with a 2-stage muffler.  Your genset will be much quieter.  I asked Centek, and they recommended part number 1529001.  West Marine sells them for $600, and it's a special order with a lead time of 3 weeks.  

Liberty44140

Really odd that it blew 90 min after shutdown. No idea how or why. Sounds like some major pressure buildup. I think I’d replace the choke and the muffler. 

Jarodjay

You all are very helpful. Thank you!

Glenny

This happened to me four weeks ago, the reason is the choke does not fully open when running. While that is happening the raw fuel is filling the muffler. When you restart it ignites the fuel in the muffler and the top blows off. I replaced my muffler and spark plug (raw fuel will ruin the plug) held the choke open manually by hand and the generator ran like a top. I let it warm up to give it a good clean up. Then after a complete cool down you adjust the choke accordingly and watch it open completely. Start your adjustment leaner to avoid the blow up again. Worse case too lean it will start a little harder but not rich with fuel then richen up from there.

Aqua_Aura

This video may help with the choke adjustment. Saw this when it first came out but didn't think much of it. 

https://youtu.be/3XE6OOaTw-A

Jarodjay

Thank you Aqua Aura. I am going to do this. My generator current sounds exactly like the one in the video.