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Onan 12MDJC-3R/2268D Serial #16c859299 White Smoke


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  #31  
Old 01-05-2018, 02:43:47 PM
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Default Re: Onan 12MDJC-3R/2268D Serial #16c859299 White Smoke

If you are using the original pump , with the original block and the original shim then you should not need to remeasure or change the shim. I am thinking you are 1 tooth off. It has happened to me before though not on an Onan , made bigtime smoke. Give it a try with the method from the manual. The shim is the gasket. Cheers Dan
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  #32  
Old 01-05-2018, 02:49:30 PM
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Default Re: Onan 12MDJC-3R/2268D Serial #16c859299 White Smoke

AWESOME DAN,

I will pull it and turn one tooth to line up and try it, I will tell you, I can pull this apart real fast now, maybe even blindfolded. LOL

Thanks Dan, until I start her up have a great weekend everyone, I should get to it this weekend, I will keep all posted with the outcome.

Thanks again all
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Old 01-05-2018, 03:25:38 PM
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Default Re: Onan 12MDJC-3R/2268D Serial #16c859299 White Smoke

Proper shim thickness will be stamped on the block near the injection pump mounting. It is in thousandths; i.e, 0.0xx. The "gasket" to prevent oil leakage is the o-ring on the pump. Remove the flywheel cover and follow the procedure to determine the proper "button" for correct timing. The pump is driven off the camshaft, so any movement of the flywheel is NOT magnified at the pump drive, rather reduced and may not be discernible. You CAN flow time the pump, no micrometer needed, and it is very accurate. Follow the procedure in the manual to the letter, change "buttons" (NOT shims, they only control gear lash) as appropriate and, if injectors and compression, valve lash, etc., are correct you should not have any white smoke, except, perhaps, on startup when cold. zuhnc
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Old 01-06-2018, 04:58:51 AM
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Default Re: Onan 12MDJC-3R/2268D Serial #16c859299 White Smoke

The shims on the JC are for gear lash not timing. Use the flow timing method. That is the best way. It is better. In the field we didn't have time for the mic method. That was more for setting up a new unit system. The flow method was much better. Clean the shims that came off with it and put them back on. The flow method takes longer but it will give you a true position of the system.
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Old 01-06-2018, 08:53:34 AM
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Default Re: Onan 12MDJC-3R/2268D Serial #16c859299 White Smoke

My retrofit Generac governor goes to full speed immediately on the Mercedes diesel I have on my set. I used a shut off switch to the governor board power to start at an idle speed. CK
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Old 01-08-2018, 10:04:49 AM
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Default Re: Onan 12MDJC-3R/2268D Serial #16c859299 White Smoke

Ok everyone, I had a little time and I mean a little time this weekend (its over already?) and did check valve clearance all good, rechecked and set inj pump to line up with PC marking on flywheel/pin hole on IP side and its a hair before PC mark on FW. We still have white smoke, I got it running again and it seemed like it started a little bit easier/quicker than the times prior adjustment to IP, when running I cracked #4 fuel line a little and had a tiny steady stream almost fast dripping from conection point and smoke let up a little but started to run rough, I tightened it back up and motor smoothed out, I dont remember If I told everyone but this motor runs smooth from what I can tell...I did not have time to flow time it, from what I have read in the manual 974-0750 Thanks again Billy J Shafer , I will be timing it using the #1 fuel line only correct? this is checking the 1st one and I am assuming all shall follow accordingly in its sequence and excatly as manufactured from ONAN in time as the #1. My question is, are there 4 buttons on this thing and do I need to check the button thickness on all 4 of them in the same way as #1 fuel line? reason why I am asking is I did not check it yet but I have a suspicion that #2 and #4 lines are pumping to much into cylinders or nozzles are set to high (of flow) into cylinder causing excessive fuel thus wet and white smoke.
after all above mentioned, I pulled exhaust manifiold and still #4&2 very wet ports...
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Old 01-08-2018, 01:36:19 PM
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Default Re: Onan 12MDJC-3R/2268D Serial #16c859299 White Smoke

How long are you letting the engine run when you start it up each time?
I believe there is only one button.
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Old 01-08-2018, 03:31:02 PM
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Default Re: Onan 12MDJC-3R/2268D Serial #16c859299 White Smoke

There is only one timing button. The camshaft has four lobes, one for each cylinder. Follow timing procedure in the manual. It is easy to have the camshaft 180* out. I believe, if the camshaft is in its proper position, the #1cylinder camshaft lobe nearest the injection pump points down and out. If all is correct, it might take 10-15 minutes for everything to come up to a decent temperature, assuming the thermostats (2) are not stuck open. zuhnc
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Old 01-08-2018, 03:44:52 PM
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Default Re: Onan 12MDJC-3R/2268D Serial #16c859299 White Smoke

Has anybody ever seen the 4 lobes on the cam worn down?
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Old 01-08-2018, 03:54:53 PM
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Default Re: Onan 12MDJC-3R/2268D Serial #16c859299 White Smoke

About 5 minutes+, it gets pretty hot, which is my next challenge. this used to be a marine cooled setup, it came with a manifold that bolts to both heads and has a thermostat elbow for connecting to hose/radiator.last time i ran it about 6 minutes and started to over heat, I shut her down before any damage. I dont know if when I bought this set he had the dual head manifold I will call it, and it has 1 thermostat on it, I replaced it with new one. currently not in it , I might have some air lock going on in it.
But my question is, I understand what your saying about letting it get to warm up, but what would that have to do with 2 out of 4 cyklinders wet on exhaust ports causing white smoke?

---------- Post added at 11:54:53 AM ---------- Previous post was at 11:51:31 AM ----------

well if its 180* out I wont be on the compression stroke right? I have verified its on compression stroke, I had the glow plug out and felt it compresing coming out as I was coming close to PC on flywheel. does this make sense for NOT being 180* out?

Please confirm

Steve
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