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Onan 6.5 MCCK Won't Run with the Release of Start Switch


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  #11  
Old 10-21-2016, 08:16:11 PM
Seahawk215 Seahawk215 is offline
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Default Re: Onan 6.5 mcck wont run with the release of start switch

Try jumping the safety switches. I use a jumper wire with alligator clips. There are 3 switches. Engine high temp, low oil pressure, and the exhaust high temp. The wiring goes to these switches and then to the positive side of the coil. Try jumping from the engine high temp to the coil first and if it stays running then you can narrow down which switch is bad. Mine always seems to be the exhaust switch that goes bad. The start switch bypasses these switches until released.
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Old 08-03-2017, 02:23:05 PM
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Default Re: Onan 6.5 mcck wont run with the release of start switch

Hey--I'm working on the same problem with my Onan 6.5kw MCCK "H" --where is this resistor that you found to be bad located exactly. The part # 353-0091. Thanks!
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Old 08-03-2017, 03:48:43 PM
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Billy J Shafer Billy J Shafer is offline
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Default Re: Onan 6.5 mcck wont run with the release of start switch

Two sheets that cover the gen section. Besides burned out resistor. The most common thing I found bad. Was item 26. Most of the time that was the problem.Go to the twinslan link we have on this site. You can download the parts manual 927-0224. I forgot the service manual number but it will be there.
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Old 08-03-2017, 04:42:56 PM
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Default Re: Onan 6.5 mcck wont run with the release of start switch

Item 26 seems to be the bridge rectifier if I recall correctly. Cheers Dan
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Old 08-07-2017, 02:59:51 PM
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Default Re: Onan 6.5 mcck wont run with the release of start switch

Quote:
Originally Posted by Billy J Shafer View Post
Two sheets that cover the gen section. Besides burned out resistor. The most common thing I found bad. Was item 26. Most of the time that was the problem.Go to the twinslan link we have on this site. You can download the parts manual 927-0224. I forgot the service manual number but it will be there.
Hey Billy! I traced my generator trouble to the genset itself. I found the same resistor that Tresea had posted a pic here earlier and in the same exact location. I removed the resistor and found the onan part # is 353-0060 and has 7.5 ohm on it also. I'm a little confused as you had said that the number is 353-0091. The resistor on mine looks like it's been there for many years--I've had the boat for 4 years and no work has been done the electrical side of the generator. The number is clear on the resistor.
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Old 08-07-2017, 09:24:44 PM
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Default Re: Onan 6.5 mcck wont run with the release of start switch

Onan did update numbers at times. Never did understand why.
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Old 03-22-2018, 10:19:22 PM
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Default Re: Onan 6.5 mcck wont run with the release of start switch

I hope my reactivating this thread is ok, as I thought it better to continue this conversation than start all over. Please read the entire above thread.
This scenario was exactly the problem on my newly acquired 6.5NH3CR/16004k H783378068

I swapped the diode from a known running 6.5 with no improvement, and tested the oil pressure switch and it grounded within a second of engine rotation then opened a few seconds after rotation stopped. Time to find the resistor in the genhead - could they have put it in a more difficult spot to get my fat fingers too?
It is obviously damaged, and is an open circuit. Mine is labeld 353-0060 7.5 ohm.
A quick look at replacements of same style Onan brand, runs from $30 to $60. Spec seems to be 5% and 25 watt.
I don't see any thread where others have simply replaced this resistor with a much less expensive Aluminum housing wirewound unit of same spec, or ceramic block style. Why not? The cost on those with shipping is roughly $10.
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Old 03-26-2018, 09:42:08 AM
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Default Re: Onan 6.5 MCCK Won't Run with the Release of Start Switch

So just to close out my comments above, I replaced the 7.5 ohm resistor with the ceramic block style, and replaced K3 as it wouldn't latch consistently, and everything works like it should now. Ran it for better part of 3 hours yesterday loaded with a load with no issues.
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