12.7 60 series no start
03-17-2025, (Subject: 12.7 60 series no start ) 
Post: #1
12.7 60 series no start
Have a 12.7 Detroit series 60 DDEC IV that had the bull gear bearing go out. Stripped out air compressor gear and chipped teeth on crank gear. Engine would still start and run, but no throttle due to fuel pump being driven off air compressor. Cam gear wasn't affected and stayed in time. Replaced bull gear and crank gear, timed all gears per manual spec.
After everything is assembled engine doesn't start or fire. It produces insane copious amounts of thick white smoke while cranking. Everyone is saying its a timing issue, however i double checked everything including pin on cam to verify it wasn't pressed into the cam. replaced srs and trs sensors. tried spare ecm, no change.

Any ideas??
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03-17-2025, (Subject: 12.7 60 series no start ) 
Post: #2
RE: 12.7 60 series no start
just a guess, I am not a detroit guy...
cam timing 180 degrees out?.


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03-17-2025, (Subject: 12.7 60 series no start ) 
Post: #3
RE: 12.7 60 series no start
Thinking out loud, are you able to see in DDDL if the Sync Reference Sensor (SRS) Recieved is reading Yes/No when cranking? Otherwise, ohm out the injector harness at the ECM for a possible injector harness shorted out to the cylinder head. Lastly, I believe the Timing Reference Sensor (TRS) is shimmable if you don't have enough sensor gap. If you could find a known good waveform for the SRS and TRS you could hook up an oscilloscope to both of them and rule out sensors not reading properly.

Edit: Thinking about it too, the crank sensor has no missing teeth, so an oscilloscope would be able to confirm signal integrity but wouldn't be able to verify timing in spec.
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03-17-2025, (Subject: 12.7 60 series no start ) 
Post: #4
RE: 12.7 60 series no start
Definitely sounds like a timing issue to me from my experience with them. Time to get a dial indicator out and check cam timing that way. Its the only way to be sure timing is correct, I had one that with all the timing marks lined up on the gears timing was wrong, moved the cam gear one tooth over and it measured out perfect and ran like a top.

Also, just because the cam gear stayed in time doesn't mean it couldn't have jumped on the crank and had valves make contact and mess some up enough to cause issues.
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03-18-2025, (Subject: 12.7 60 series no start ) 
Post: #5
RE: 12.7 60 series no start
Well turns out when Jr yanked the gear housing off it ripped the wires out of the srs plug and they were swapped in the plug when he repaired it
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03-18-2025, (Subject: 12.7 60 series no start ) 
Post: #6
RE: 12.7 60 series no start
Swapped the 2 wires and she fired right up
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 Thanks given by: hhow55




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