| [GMCnet] Motor Knocking Part 1 [message #204184] |
Tue, 09 April 2013 18:37  |
Richard Waters
Messages: 4
Registered: February 2004
Karma:
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Junior Member |
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It's been a while since I posted, but I'm a bit frustrated now and think
maybe someone here might have some ideas. I've already consulted with Ken
Henderson, Emery Stora and Matt Colie offline.
We were supposed to leave this past Sunday on a long anticipated, month long
trip throughout the SE US. This would have been our first long trip since
we bought the coach 15 years ago. However, at the 11th hour, the 2-year old
motor, with 10,000 miles on it started " knocking" just when I started it up
to move closer to the house so my wife could start packing it for the trip.
What a bummer! Another GMC trip postponed or possibly cancelled again.
Since then I confirmed with my timing light that the knock sound happens
once with each strobe. So that apparently means a valve train issue or
piston slap and maybe nothing bad downstairs like rod or main bearings.
With only 10,000 miles on the engine I'm guessing it is probably not piston
slap. A collapsed lifter this early in the game? I'm thinking that's not
the problem either.
Yesterday, I checked the top of the engine with a stethoscope, I wasn't able
to locate the source of the noise. Everything on the top seems to sound the
same. I ran the engine and shorted each sparkplug wire one at a time and
also no change. I watched a few YouTube videos about collapsed lifters and
some sound just like mine does.
https://www.youtube.com/watch?v=0iFElc70zXA
I also found a reference Google that suggested the sound could be a loose
flexplate screw. However, I went out with my stethoscope and listened to the
transmission bell housing and couldn't hear anything there except perhaps
the wine of the chain. It does seem the sound is coming from the front of
the engine. I did not physically check the flexplate.
A little background, about 10 days ago, I had Blackstone Labs check my oil.
The report indicated that the oil was positive for coolant, sodium and
potassium. Not a good thing, but the levels were relatively low. I have
the oil checked each 2,000 mile oil change and that's the first time that
happened.
See part 2 for more details
Richard
SE Michigan
www.PalmBeachGMC.com
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