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My truck has been making a knocking noise upon acceleration. Today the knocking is constant and louder. What could this be? Pistons? Oil sludge? New motor?

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  • Can you add some information? Does the knocking stay in time with engine speed or road speed? Does volume of the knocking increase under certain conditions? How many miles are on the truck? Have you looked for metal shavings in the oil during an oil change? Thanks and Cheers! Commented May 10, 2016 at 21:24
  • Constant with engine. Louder when you accelerate. 197000 miles. Haven't noticed any shavings
    – ablank13
    Commented May 10, 2016 at 21:40
  • See my answer here....mechanics.stackexchange.com/a/29550/16882
    – Moab
    Commented May 10, 2016 at 23:56
  • Shavings will be seen in fast failures, more than likely yours is normal wear of the rod-crank bearings and crankshaft over time, this will show no noticeable shavings. The wear is slow and small particles will be drained with each oil change.
    – Moab
    Commented May 11, 2016 at 0:00

3 Answers 3

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The 3.7 is notorious for having a rocker arm fall off and or lifters collapsing. This is usually accompanied by a check engine light being illuminated.

Use a stethoscope or a long screw driver and try to isolate where the knock is coming from.

If it's coming from a valve cover, remove the valve cover and you're likely to find a rocker laying around. If this is true you need to thoroughly inspect the valve train components.

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  • Knock sounds like it's coming from the bottom of engine
    – ablank13
    Commented May 10, 2016 at 21:47
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    @ablank13 Try removing the serpentine belt to rule out a bad water pump or accessories. But if it's truly coming from the bottom of the engine you're going to need to pull the pan and inspect everything.
    – Ben
    Commented May 10, 2016 at 22:09
  • The early Hemi V8 engines had catastrophic valve train failures also, Dodge quality.
    – Moab
    Commented May 11, 2016 at 0:01
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Remove the valve cover and oil pan and inspect for rod bearing damage. Black or discolored rod caps are good indicators of spun bearings. Then, check the valve train for damage, failed lifters, heavy pitting, etc. If everything comes up good, then I suspect the timing guides or chains.

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what about 2008 Dodge Magnam-v6 ride knock

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  • Welcome to the site. If you'd like this answer taken seriously, you'd explain what "ride knock" is, and how it can be fixed or alleviated. Just saying it exists makes this a very weak answer. Commented Jul 7, 2017 at 18:48

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