dodge 4.7 liter V8

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Originally Posted By: GT Mike
Carbon knock is a possibility, but since it seems to dissipate as the temperature increases, that might not be the most plausible explanation.

I shudder at doing a top engine cleaning on an engine with an inverted long-runner plenum such as this engine has due to the fact that any liquid could puddle up in the bottom and get suddenly get sucked into one cylinder. I'd rather live with a little knock than hydraulic a cylinder. Unless someone has a fool-proof method, I'd be interested in listening...


Note that in our case it was quite loud at cold start and quieted down quickly as it warmed up... sound familiar?

2 cups of Kreen in the gas quieted down our GM V8's in just a few minutes when we figured out we had carbon build up. I definitely do not like putting any liquid into a 'dry' manifold these days for the exact reasons quoted.

Many of the common gasoline additives can help with carbon knocking, but it is tricky to be sure if you have it!
 
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Originally Posted By: grease_monkey
I have a 4.7 liter V8 with a cold knock, that lasts 30sec-50 sec uppon start up when engine has been sitting for 6 or more hours. I was told that it was a typical mopar knock. and that nothing can be done about it. i know my engine is clean and free from sludge. i was told that it was the hydraulic lash adjusters has anyone ever had this issue on the 4.7 V8?


grease_monkey,

It does appear to be a normal occurance cuz it happens to my 4.7 liter engine too. For me it usually happens when my motor sits in the garage for a couple days. After that it's pretty quiet when started. Personally I wouldn't worry about it unless it goes for over a minute or two at the most.

Durango
 
could be a lash adjuster, air purge solenoid, or broken exhaust manifold bolt.
 
For what it's worth, we have a 2008 Ram with the HO 4.7L at work. It sometimes sits for days at a time, but we've never had any knocking noises from it. In fact, I think it may be my favorite of all the "small" V-8s I've driven. Right now, it has Formula Shell 5W-20 and a bulk oil filter from a Jiffy Lube oil change last year.
 
It seems like 2005 was a problem year for these engines. My dad has a 2006 that he bought brand new, and it's always had a diet of Mobil 1 5w30 with only Mopar filters. It's got a tiny bit of timing chain/valve train rattle on a cold start, but no audible piston slap, or any other unusual noise.
Another buddy of mine just got rid of a 2005 Dakota because it had a nasty cold start knock. I listened to it and it was considerably louder than mine, but it too went away once the engine got up to temperature.
I'm wondering if it has something to do with the fact that 2005 was the first year they started using EGR valves on these engines. Perhaps carbon from the exhaust gasses getting recirculated back into the plenum found its way onto one or more piston tops/ring lands? Just a stab in the dark.

One other thought on piston slap... It seems as though the break-in method when an engine is new is definitely a contributing factor on how it's going to be when it's got say 100k on it. The ones that were just bumbled around town and/or given a very easy, gentle break-in tend to have piston slap and other noises when they've got some miles on them. The ones that were ran hard when new almost always are nice and quiet later on in their life.
That being said, after about the first ~500 miles, I told my dad to drive his truck like he stole it. At 75k, it's still as nice and quiet as the day he took delivery. He still drives it like he's on the way to a fire too.
laugh.gif
 
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