12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

Engine nock at low rpm

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  #21  
Old 06-18-2012, 04:05 PM
dixierebel0213's Avatar
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got a factory lift pump? after i pulled fuel plate in mine it took about 1 month of lead foot to starve lift pump enough to tick loudly at idle to about 1200 rpms then i could not hear it. its mid engine mounted to block so everything carries the sound. loud under hood loud in fender well loud from the front. i put a raptor on with self built filter setup. if you havent already put an airdog on it and get a tork technology ofv truck runs smoother and fuel system will now be supported well enough to run 370s and pump with divertor valves. if it doesnt cure the noise at least the fuel setup will handle a built motor. in my experience melted pistons dont get quieter, bc they just slap harder and faster.
 
  #22  
Old 06-18-2012, 08:49 PM
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yes. i have factory lift pump. but the noise is not a ticking. its almost a rattling noise and its unbarably loud. mid engine halfway back. and i have no loss of power. wouldnt that make u loose power? also. i have no fuel shut off selinoid so i can hold lever down. when i hold fuel shut off lever down and crank my motor it sounds like a 3 nocks real fast until motor turns full rotation back to that point then does it again.
 
  #23  
Old 06-21-2012, 02:45 PM
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when engine is running and knocking put your hand on plunger and see if the noise changes, and you will feel it in plunger. my didnt lose power at first then slowly started from about 2700 and worked its way down. may not be lift pump thats where it sounds like to me
 
  #24  
Old 06-21-2012, 03:21 PM
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this just dawned on me!!! what is the new injection pumps timing at??? anything over 16* rattles and carries on. the higher the timing the more she sounds like she is going to blow. is it harder to start?
 
  #25  
Old 06-21-2012, 04:12 PM
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Timing should not sound like a knock. My p24v is set at 28* and it starts and idles fine...no knock

My 12v i was running at 28* also and again never sounded like a knock.

Sent with a Droid RAZR in one hand and 14,000 volts in the other.
 
  #26  
Old 06-21-2012, 05:43 PM
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agreed defenatly not a knock. just a very different sounding rattle compared to stock. i know i was worried with the first one i turned up.
 
  #27  
Old 06-22-2012, 08:58 AM
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yeah it kinda sounds like dropping loose change into the engine... it really sounds nice when you start putting real big injectors in also like the john deere nozzles that are in mine
 
  #28  
Old 08-19-2012, 03:49 PM
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Found out what it was.. TC bolt snapped off at head.
 
  #29  
Old 08-19-2012, 05:20 PM
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glad it was a simple fix
 
  #30  
Old 08-19-2012, 11:55 PM
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wow never even thought about that being the problem
 
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