Discovered a knock

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I recently discovered a knock coming from my car a couple days ago. When I start my engine everything is fine and dandy nothing unusual, however for some reason I decided to bring my revs up to about 2k while I was still in park getting myself situated to leave and I discovered that as the engine brought itself back down to 800 revs it was knocking. So I slowly reved it again and no knocking was present while I was reving but when I would release the throttle it would knock until it settled at 800 again. I put her in drive since I had to be at work and no knocking while I was driving, I was checking very cautiously as well, radio off, windows down, basically leaning as far forward as I could to here any noise. I couldn't hear anything. Once I got to work and parked it I reved it again and no knocking what so ever. When I was off work and I returned to the car to grab some lunch (about 2 hours after arriving) I started the car everything was like normal, reved and no knocking yet again. Same thing when I left for the day at 5pm, no knocking.

So it seems as though this only occurs when the engine is 100% cold. Once its been run for a while and the engine sits for a few hours but is still warm from the previous drive, the knocking is still gone. Since this happened I check for it every time I get in the car and its done it the past 3 days I've used the vehicle. I normally use it 3-4 days a week.

I did an oil change on March 22 with 10w30 PU and a regular Bosch filter. The temp was in the 70s and even had two days of low 80s at the time, however we've had a lingering winter front come back down for the past week or so and brought temps back down into the 40s for a couple days and now we are back into the 60s, hopefully for good this time. The car was purchased in late January and I'm not sure what oil the dealer used, I'm assuming 5w30 conventional. Is it possible that the 10w30 was the cause and it was too thick for a 30-40 degree morning?

This is a video of what I experienced. This is not me or my car, but a video I found that showed the noise I experienced, for him it is only about 1 second right at start up but that is the noise I am experiencing when the revs decrease as I previously explained. You can hear with him, once he shuts it off and restarts it towards the end of the video there is no noise at all.
 
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Sounds like oil not making it to the lifters. It's not harmful, just annoying. It may persist into the oil warms up a bit.

Since it started pretty much when you changed the oil, I would assume it's that. Lots of cars have their lifters change sounds with different oils. It's usually a matter of experimentation to figure out what's better and what's worse.

Bottom line is there will be no harm done to leave the oil in there. It will probably get better as it shears down.

What kind of car is this on? 10/30 is thick, at least for the dudes around here
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Originally Posted By: antonmnster
Sounds like oil not making it to the lifters. It's not harmful, just annoying. It may persist into the oil warms up a bit.

Since it started pretty much when you changed the oil, I would assume it's that. Lots of cars have their lifters change sounds with different oils. It's usually a matter of experimentation to figure out what's better and what's worse.

Bottom line is there will be no harm done to leave the oil in there. It will probably get better as it shears down.

What kind of car is this on? 10/30 is thick, at least for the dudes around here
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Yes I wish I did not need 10w30. It is for an '07 Charger with the 3.5l V6 and it is under warranty so unfortunately 10w30 needs to be used. Thanks for the input, I was leaning towards this conclusion as well.
 
First what kind of guarantee do you have from the dealer?
I would get it in to them ASAP and let them diagnose it and document the fact that you were complaining of a engine knock.

The noise could be a host of different things from an impending major catastrophic event to a harmless nuisance.
Some engines like early 4.6 and 5.4 Fords sound like a tin can full or marbles when cold,knocks,rattles,ticks,thumps you name it.Ford claims its all normal.

This is going to be near to impossible to diagnose without having the car there and hearing the exact noise from your engine.
Go back to the dealer and give them as much detailed information as you can.Mention you only revved it slightly other wise they might to blame you for revving a cold engine and causing the damage.

Edit: My first thought was lifter/lash adjusters but you want to 100% sure,i would hate for you to just go with that diagnosis and have problems later with the engine.
 
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Originally Posted By: Trav
First what kind of guarantee do you have from the dealer?
I would get it in to them ASAP and let them diagnose it and document the fact that you were complaining of a engine knock.

The noise could be a host of different things from an impending major catastrophic event to a harmless nuisance.
Some engines like early 4.6 and 5.4 Fords sound like a tin can full or marbles when cold,knocks,rattles,ticks,thumps you name it.Ford claims its all normal.

This is going to be near to impossible to diagnose without having the car there and hearing the exact noise from your engine.
Go back to the dealer and give them as much detailed information as you can.Mention you only revved it slightly other wise they might to blame you for revving a cold engine and causing the damage.

Edit: My first thought was lifter/lash adjusters but you want to 100% sure,i would hate for you to just go with that diagnosis and have problems later with the engine.


The dealer only had a 30 day warranty, that has since expired of course. I've got a 5 year/100k mile warranty with AUL on the vehicle though.
 
Even if you have a deductible it would be IMO worth having it looked it and documented if for nothing more than peace of mind sake.
 
With a dial up, I can't get the video.
But a rod knock would not get better as it heats up.
So the valvetrain is quite likely.
 
Decided to go out for a drive today so I thought I'd record my start up. Temperature was 68*. You can hear the knocking that I'm talking about while I'm in the cab, when I'm out looking into the engine bay you cant really hear anything, I think the wind, music, normal engine noise just combined to make one big mess.
 
Doesn't the manual allow any alternative to 10w30? I'd definitely try a 5W, or even 0W, to see if it resolved the problem. The protection provided by a 0W-30, or 5w30, will be no less than a 10w30 oil.
 
Originally Posted By: rshunter
Doesn't the manual allow any alternative to 10w30? I'd definitely try a 5W, or even 0W, to see if it resolved the problem. The protection provided by a 0W-30, or 5w30, will be no less than a 10w30 oil.


It allows for 5w30 only for temps below 32*. It will certainly be getting 5w30 for the winter but until then it has to be 10w30.
 
Do those engines have piston slap issues like the Ford 4.6's would sometimes have? I know the 4.6 in my 02 Mustang gets some piston slap at a certain RPM when completely cold.

Since you have an extended warranty just take it in and have it checked out. Those aftermarket warranty places will usually use anything you might do yourself as a reason not to cover repairs.
 
Originally Posted By: AdRock
Do those engines have piston slap issues like the Ford 4.6's would sometimes have? I know the 4.6 in my 02 Mustang gets some piston slap at a certain RPM when completely cold.


I'm not sure if these engines are prone to piston slap, however you question made me think of something.

These Chrysler 3.5l V6s are prone to oil consumption, ever since I started my own oil consumption study on this engine with the last oil change. It has been 250 miles on the dot from March 22-April 2 and yesterday I had to use 8oz of makeup oil to bring it back to the MAX line on the dipstick. If this consumption stays linear it would be exactly 1 quart every 1k miles.

The point of me bringing this up is this, piston slap is the horizontal touching of the piston to the bore, if there is space for the piston to move, wouldn't that explain where the oil may be going?
 
That sounds too conspicuously like piston slap or rod knock to be anything else.

Much less ambiguous than this:



Sorry for being an [censored] and derailing the thread but what do you guys think about how my engine sounds?

Piston slap, exhaust leak? Or just normal diesel knock/sound?
 
Originally Posted By: maersk
That sounds too conspicuously like piston slap or rod knock to be anything else.

Much less ambiguous than this:



Sorry for being an [censored] and derailing the thread but what do you guys think about how my engine sounds?

Piston slap, exhaust leak? Or just normal diesel knock/sound?

Hey start your own thread! Nah, just kiddin' I gotta be honest, that just sounds like a normal diesel rev. Maybe my ears aren't tuned enough but it sounds normal to me.
 
Originally Posted By: RamFan
Originally Posted By: rshunter
Doesn't the manual allow any alternative to 10w30? I'd definitely try a 5W, or even 0W, to see if it resolved the problem. The protection provided by a 0W-30, or 5w30, will be no less than a 10w30 oil.
It allows for 5w30 only for temps below 32*. It will certainly be getting 5w30 for the winter but until then it has to be 10w30.

Okay, I've just read the manual for a 2007 Dodge Charger and it's only served to reinforce my opinion that Chrysler is home to some of the stupidest recommendations I've ever seen. According to DaimlerChrysler, 5w30 is only suitable when the temperature is not expected to exceed 32F (0C) at any point during the oil change interval. Un-friggin'-believeable...
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I'm only surprised that they don't recommend 20W-50 if the temp will ever exceed 68F (20C) during the OCI. Is it any wonder Chrysler is a perpetual also-ran?
 
I think they're saying obviously 5W30 can only be used below 32F. It is really not as bad as it sounds because 10W30 flows quite well down to freezing. It is a little strange though because 5W30 seems to have as good or better high temperature and HTHS as 10W30.
 
Originally Posted By: mechanicx
I think they're saying obviously 5W30 can only be used below 32F. It is really not as bad as it sounds because 10W30 flows quite well down to freezing. It is a little strange though because 5W30 seems to have as good or better high temperature and HTHS as 10W30.

They actually state that 10w30 should be used unless the temperature will fall below 0F (-18C), and never be above 32F (0C) during the OCI.

*Ring, ring, ring!!!* "Hello, Chrysler? This is the 21st Century calling..."
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