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Old 05-30-2007, 11:37 AM   #1
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Default Valve clatter

Almost since the engine was new (and before nitrous injection) every so often immediately at startup, I get a loud what sounds like a multi valve clatter. This summer it is happening more often. Anybody else with a Northstar has this condition? It only happens for like a second.
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Old 05-30-2007, 11:55 AM   #2
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Same here Venom. I notice it only for a few seconds as well.
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Old 06-01-2007, 08:54 AM   #3
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I will check mine out and get back to you. Like mthe new pic!
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Old 06-01-2007, 09:02 AM   #4
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Same here never really noticed but I will listen a little more intentive
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Old 06-01-2007, 06:17 PM   #5
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yup i have the same... but mine isnt just one start up...


I think the new engine is on order... gotta love warranty.
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Old 06-02-2007, 01:06 AM   #6
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Done some researching through the Cadillac forums and came up with that it sounds like what they describe as "cold carbon rap". Rather than steal another forums text I am linking here to a nice read on the problem. The only solution seems to be a good injector cleaner and some real WOT'* after the engine is hot. After reading the thread I realized without my license my car hasnt seen much upper RPM exercising lately. Northstar tolerances are so close that they build up carbon very easily.

http://www.cadillacforum.com/m_2400/tm.htm
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Old 06-03-2007, 08:12 PM   #7
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Quote:
all without creating a spectical of yourself and attracting the attention of cops. You can do it on most any freeway and stay within the 70-75 MPH range allowable. Once a week like this will keep the engine cleaned out and healthy and is DEFINITELY recommended for the Northstar in particular.



I do notice after a good **** run she is quieter and sounds healthier. I will sometimes coming off the Highway shift in to 2nd to create what he refers to as over run.. But on a engine as sophisticated as the LD8 is this really necessary ?
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