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Onan MDKD Repairs


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  #1  
Old 03-01-2016, 07:12:24 AM
Viking66 Viking66 is offline
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Default Onan MDKD Repairs

I had this thread going but wanted to become more specific to the Genset I have so I want to start a new one.

http://www.smokstak.com/forum/showthread.php?t=155482

I have the Injector Pump all fixed up but have a leak on the top where the fuel lines connect. I will receive both the O-rings and small Copper Washers tomorrow.

Does anyone know the torque value for them? I may have missed it in the manual.

I am also contemplating re-building the Control box since my search for one has yielded no results. Anyone ever done a project like that that can pass on some tips. I was thinking maybe an electrical box of some sort close in size.

Thanks.
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Old 03-02-2016, 07:55:50 PM
Viking66 Viking66 is offline
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Default Re: Onan MDKD Repairs

I got the O-rings in and on. I just gave them a nice snug and now I have no leaks on top of the Injector Pump

Now I just need to figure out why the pump doesn't run when it should and why the Stop solenoid doesn't pull in and hold. Both are on the same circuit, so I just need to get a good look at it all.
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Old 03-09-2016, 07:24:43 AM
Viking66 Viking66 is offline
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Default Re: Onan MDKD Repairs

Hi All.

Issue: Genset will run Only if I hold the fuel control open solenoid full in. The second I let it go it quits.

I have been messing with this beast more and more each day and I think the Stop Solenoid may be the culprit?????

I have been checking the circuits and continuity of the wires for the Control and even changed out one of the Relays (K14) just to test my theory that it wasn't bad. I tested the Circuit Breaker and found that it was not working, so I installed a fuse to keep that connection together for now.

I do not want to spend $40.00 or so bucks on a new Solenoid and have it not be the culprit. I can touch both the + and Aux with 12v and the Solenoid activates. When I hit the start switch the Solenoid pulls in, but releases as soon as I let go of it.

Any ideas are Greatly Appreciated!!!

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Old 03-09-2016, 07:30:07 AM
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Elden DuRand Elden DuRand is offline
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Default Re: Onan MDKD Repairs

I'm not familiar with your generator but can tell you that the solenoid is okay if jumpering it makes it pull-in.

If the control circuits are working okay, you could have a tripped overspeed sensor, a bad temperature sensor or a bad oil pressure switch. On a lot of generators, these items are connected to the run circuit and will cause the engine to stop unnecessarily if they go bad.

The Onan experts here can tell you more.
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Old 03-09-2016, 02:51:28 PM
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Default Re: Onan MDKD Repairs

If you disconnect the solenoid + wire you can test it by moving the injection pump arm. With the arm in the off position the resistance between the + terminal and the - terminal will be around 1 ohm or so, when you move the lever to the on position at the very bottom of it's travel the resistance will jump to around 13 ohms indicating that the aux contacts have transferred. You may have to adjust the plunger a bit to get the aux contacts to make. If the resistance goes up to some value higher than 13 ohms or thereabouts the hold coil may not have enough power to keep the solenoid pulled in. If the solenoid checks out as above then the problem is elsewhere. Cheers Dan
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Old 03-09-2016, 07:27:39 PM
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Default Re: Onan MDKD Repairs

Two pics...2000 words....LOL

Bad is what I am thinking????
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Old 03-09-2016, 09:37:54 PM
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Default Re: Onan MDKD Repairs

I would want to check the meter against a known resistance value if you can before condemning the solenoid. The field coil is around 12 ohms so maybe pull the rear generator cover plate disconnect one terminal of the field and check that. If your readings were offset by 3 ohms down each I would say they might be OK. What reading do you get when you touch the meter leads against each other. You should get less than an ohm if you get higher than that I would change the battery in the meter first and re check. If you can cross check with another meter like a Fluke that would be best. If you are still getting the same then it seems likely that the solenoid is weak. Cheers Dan
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Old 03-09-2016, 09:53:23 PM
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Default Re: Onan MDKD Repairs

If I'm understanding you correctly, start solenoid pulls in during start cycle, but deenergizes when you release the start switch. wire marked A11-CB12 line must have 12 volts on it during run cycle. Hold solenoid in by hand as you have been doing and check for 12 volts on that wire as it runs. if no voltage problem is upstream.

Sorry, meant fuel solenoid pulls in during start cycle.

Wire A11 CB12 Line is attached to fuel solenoid.
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Old 03-10-2016, 06:43:42 PM
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Default Re: Onan MDKD Repairs

No voltage to A11 CB12
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Old 03-10-2016, 08:12:34 PM
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Default Re: Onan MDKD Repairs

You need service manual 981-0502,it has wiring diagrams and start stop seguence explanation.
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Old 03-10-2016, 09:09:50 PM
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Default Re: Onan MDKD Repairs

Quote:
Originally Posted by akirkland View Post
You need service manual 981-0502,it has wiring diagrams and start stop seguence explanation.
That service manual is here.
http://www.twinslan.net/~n0nas/manuals/onan/
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Old 03-10-2016, 09:27:20 PM
akirkland akirkland is offline
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Default Re: Onan MDKD Repairs

A number of things must happen when this generator starts in order to have 12 volts on this wire to the hold in coil on the fuel solenoid. Oil pressure, ac output, relays must energize, as mentioned in an earlier post a safety could be giving you trouble. The manual will help walk you thru it. It also shows where some of the safeties are located and what they look like.
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Old 03-10-2016, 09:49:53 PM
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Default Re: Onan MDKD Repairs

Thanks.

I do have the manual, and the wiring diagram. It does put out AC Power, I checked that when I first got it running.

Wired the Control Power Latch together to see if it may be the cause but it wasn't.

I will check the Oil Pressure Sensor tomorrow and see what happens then. I switched out the K14 Relay and can feel it click, so that shouldn't be the issue.

I will keep hammering away.
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Old 03-10-2016, 11:18:48 PM
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Default Re: Onan MDKD Repairs

It would appear that K12 is not energizing. Check hi temp shutdown switch, must be open. Oil pressure shutdown switch is normally closed, open when running. Overspeed switch open. High temp exhaust switch open. Make sure cb12 breaker is not popped out.
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Old 03-11-2016, 10:24:33 AM
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Default Re: Onan MDKD Repairs

Verify that wires are correct as per the wiring diagram. If your safety shutdowns are working properly, and you have a new K14 relay that works, which it apparently does since fuel solenoid pulls in during start cycle. Check Ac terminals on A11 board, must be at least 90 volts ac when running. You have already jumpered S6 oil pressure switch, and you have found no bad fuses or tripped CB12 breaker, it sounds like you may have a defective A11 control board
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Old 12-06-2017, 07:34:23 PM
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Default Re: Onan MDKD Repairs

Been a few years since I opened this thread, but I think my DJE at my Camp may be toast...Not putting out AC, so I decided to look at this Genset that is currently in my Garage.

I am thinking that the High Coolant Temp Switch may be bad.

I went ahead and pulled it from the Genset and cleaned it up. As it sat it was open. I got some water boiling and put the end that goes near the Thermostat into the water for a good 2 minutes and it was still open.

Am I testing this correctly?

Thanks as always!!!
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Old 12-06-2017, 09:41:37 PM
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Default Re: Onan MDKD Repairs

I'm not sure but, I think it's more in the 300 degree range.
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Old 12-07-2017, 07:25:39 AM
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Default Re: Onan MDKD Repairs

Nothingbutdarts...you are correct that is it higher than boiling point. I looked over the schematic and it shows as a NO type switch, so instead of in the water I stuck it in the flame on my stove and sure enough it closed.

I have the Oil Pressure Switch grounded since it is a NC Switch.

I am now thinking it may be the A11 Control Board that is giving me trouble. Not sure of any way to check it besides swapping it out, but that is either a $100.00 dollar adventure from ebay, or a $159.00 adventure from Flight Systems.

Thanks for any and all advice on this matter!!
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Old 12-07-2017, 08:35:08 PM
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Default Re: Onan MDKD Repairs

If your oil pressure switch is "closed" ( or continuity) with NO oil pressure, then it must be "open" (NO continuity) with the engine running. If the wire is grounded with the engine running, the engine will SHUT DOWN. I.e, with NO oil pressure the switch is closed, grounding the safety circuit. Test by completely removing the wire from the switch and taping it. Check the switch when the engine is stopped; should have continuity (NC, as you stated), When the engine is running, the switch should be OPEN or no continuity. If it does not go open, then the switch is faulty, or you have no oil pressure. Most schematics and wiring diagrams show components in the de-energized position; no power applied, including any pressure or temperature signal. Any exceptions will be noted on the diagram. zuhnc
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Old 12-09-2017, 07:24:16 AM
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Default Re: Onan MDKD Repairs

I checked the Oil Pressure Switch, the High Temp Switch and the Control Power Latch Switch 6 and all read out good on my Multi meter.

I am going to put things back together and see if it will stay started.

If not, I will pull the wires from the NO type switches and tape them just as a double check to see if they are actually working.

My main goal for this is to convert it from a Marine to a Land version. I think my DJE at my Swamp Camp has bit the dust (No AC output) and i will be needing another unit out there.

I found out that the Exhaust Manifold is $152.00 Ughhhhh I think I can use the one from the Marine version, just no coolant going through it and an adapter to install a regular style exhaust.

Just trying to work things out
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