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Onan MEP-017-a starter problems


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  #1  
Old 11-04-2007, 07:10 PM
sarge155 sarge155 is offline
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Default Onan MEP-017-a starter problems

hello, i have a old military generator. it runs great except for one thing. the starter sticks when i start it. I have changed the starter, changed the starter relay, start switch, remote/local switch and it still does the same thing. When I start it the starter keeps running. I dont know what else to do and hope one of you might have an idea for me....ths
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  #2  
Old 11-04-2007, 07:43 PM
Gunny Gunny is offline
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Default Re: mep-017-a starter problems

Use a VOM and see if you are getting a potential to the starter pull in coil (small terminal) If so, you have an electrical problem. You did not mention the make/model of the generator. They usually, not always have a start disconnect scheme to take the starter out of the circuit when the engine is running. Different makers use different ways to do this, oil pressure, engine speed, a mechanical speed switch, alternator making voltage, generator end making voltage. Sometimes there are a combination of these, a primary and a secondary.
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Old 11-04-2007, 07:51 PM
sarge155 sarge155 is offline
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Default Re: mep-017-a starter problems

Thx for your reply Gunny...The machine is a MEP-017a 5kw...military gen set. I have done all but pull my hair out on this thing...any ideas would be helpful
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Old 11-05-2007, 09:58 AM
IanR IanR is offline
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Default Re: mep-017-a starter problems

Is the starter not denergizing or is it just staying mechanically engaged to the ring gear? I don't know if it would apply to your set or not, but I know that with smallblock Chevy engines some times the starter engages the ring gear teeth too deep and gets hung up in the ring gear after the motor starts. In the case of the smallblock Chevrolets you have to shim the starter away from the ring gear. This may not even apply to your set, but I figured I would throw it out there anyway.
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Old 11-05-2007, 07:47 PM
sarge155 sarge155 is offline
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Default Re: mep-017-a starter problems

thanks for the reply, but the starter stays energized. this is definently driving me crazy trying to figure out what it might be
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Old 11-05-2007, 08:36 PM
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EricWood EricWood is online now
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Default Re: mep-017-a starter problems

Does your genset still have readable schematic diagram placards? If so, follow the wire back from the starter solenoid coil. Looked in my "virtual" stash of books, but all I have is the parts manual for this one.

Someone here that has one should be able to help you out with following the wire logic back to the start/stop switch. As Gunny mentioned, you've got either a missing start-disconnect signal, or a relay that signal should be driving is bad, or bad wire somewhere.

Is it making AC volts when it starts up? Is it showing good oil pressure on the gauge, and have you checked the low oil pressure switch with an ohmmeter?

eric
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Old 11-05-2007, 08:51 PM
Rich Mc Rich Mc is offline
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Default Re: mep-017-a starter problems

Have you checked the diode that is across terminals 1 and 6 of the relay board? At a glance it seems that a shorted diode may allow a latching function to the starter selenoid thru the contacts and coil of relay K4 and normally closed contacts of K2.
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Old 11-11-2007, 07:17 PM
sarge155 sarge155 is offline
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Default Re: Onan MEP-017-a starter problems

ok...worked on it yesterday. took wire off low oil pressure switch and the starter cranked fine and didnt stick. but, it wouldnt start the generator. it tried to start, would hit only. I beleive it was because of the wire i took off the low oil pressure switch does run through the starter and wont let it start as a fail safe method. does this sound like if i replace the oil pressure switch it would cure my problem??? I am calling the pressure relay a switch..I guess it is the same thing..
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Old 11-12-2007, 04:30 PM
armandh armandh is offline
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Default Re: Onan MEP-017-a starter problems

that is not the problem [IMHO]
try taking the wire loose from the start selonoid and hold it on the terminal.
put a volt meter on the line from the starter to the solonoid.
when it starts remove the control wire. if the starter sticks and the voltage stays at the battery level, new or not the solonoid is sticking
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Old 11-12-2007, 09:54 PM
Rich Mc Rich Mc is offline
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Default Re: Onan MEP-017-a starter problems

I believe that; If the local-remote sw is in the local position and if the normal-emerg start-emerg stop is in the normal position and if the oil pres is zero and if diode (CR) is shorted / defective; then shorting the black wire that attaches to the oil pres switch and also connects thru contact "B" of the engine/generator control cable, to ground should engage the start cycle and keep the start selenoid energized until the engine has been stopped at which time the oil pres will return back to zero opening the oil pres circuit and de-energizing the starter circuit. The start circuit relay can only be energized thru the start/stop switch and maintained by the switch or thru the defective diode.
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Old 11-12-2007, 10:33 PM
Rich Mc Rich Mc is offline
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Default Re: Onan MEP-017-a starter problems

Referencing My Last POST Whoops I missed a set of relay contacts. To test whether the diode is defective don't ground the oil switch as I stated but instead short the terminal 2 (minus side) of the hour meter to circuit ground and if the diode is defective this will begin a normal start cycle. If not; you will just hear some relay clicks.
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Old 03-22-2008, 09:10 PM
sarge155 sarge155 is offline
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Default Re: Onan MEP-017-a starter problems

OK< its been a couple of months since my last post. The weather has been crapy and havent been able to get the the farm to work on generator. Here is what I have done this weekend. I purchased new diode and removed the old one and put the new one on the machine. I put it back together and now it will crank and crank and crank. Doesnt want to start. It will start in emergency position though with the pull cord. I wonder, did I put the diode in backwards. I did check the old diode with the meter and I get a reading both ways. So, i beleive the old diode is bad and am thinking i put the new one in backwards. does this sound possible???
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Old 03-23-2008, 07:02 PM
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Jim McIntyre Jim McIntyre is offline
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Default Re: Onan MEP-017-a starter problems

There seem to be two threads on this topic. Let's post here:

http://www.smokstak.com/forum/showthread.php?t=42994
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