Slight knocking sound on cold startup

[Tangent]

I have a 2016 Ram with the 3.6 with 120K.

Recently, there is a slight flapping or light knocking sound coming from under the hood on cold startup. It only lasts about two seconds, then is gone.

It runs and drive like it was new, so I'm wondering if it's an exhaust issue, since that all heats up quickly.

 

[ramffml]

Without audio we're all just guessing. Two suspects are exhaust and maybe a poor oil filter that is letting oil drain back down from the engine/lifters.

 

[jws123]

Your most likely just hearing the noisy 5.7 mds lifters its normal on startup.

 

[OC455]

Your most likely just hearing the noisy 5.7 mds lifters its normal on startup.

He said he has a 3.6L V6....

 

[jws123]

He said he has a 3.6L V6....

Pre sure it didnt say before assumed 5.7 unless I miss read.

In that case best bet is to upload vid of the noise.

 

[Tangent]

Thanks guys! now it's quit doing it. weird.

 

[Jeepwalker]

Lot of my vehicles do that ...and have been for years ....lol

 

[Dodge 1500 4X4]

Lifters, cam bearings, mains and rods bleed down, sometimes the bypass valve in oil filter can't hold pressure or bypass valve is going bad, doesn't the 3.6 have just a canister oil filter?

 

[PoMansRam]

If it persists, bad rocker arms aren't unheard of on the pentastar, or stretched timing chains if not well maintained or super high mileage. I think there's 5 chains on these buggers.

There isn't any exhaust manifolds on pentastars. The exhaust outlets are cast into the cylinder head. The catalytic converter assemblies bolt directly to the aluminum cylinder heads. Cool design actually. Never heard of an issue with it.

 

[Zorin]

Here's a nifty tale from the shop for you, on two different cars that relates to you.

First car - my 2002 Ford Mustang GT. Slight rattle at start up, and while cold, a slight rattle right before I shifted to 2nd. You would SWEAR it was either timing chain tensioners, or a questionable rod bearing. Noise went away COMPLETELY after the engine got some heat in it, not even fully warm.

Second car - 2016 Chevrolet Suburban with the 5.3L engine. Cold start, made a knocking at idle for roughly 3 minutes. Take it out, and it makes NO noise at all, except right between 2000 and 3000 RPM if you had your foot in it. The fact that the foot was in it proves that it is NOT a rod bearing, as those won't knock under high load.

Problem with both cars after targeted diagnostics - water pumps were making racket, and then shutting up after expanding with a little heat.

Check that out GOOD. Water pumps can make odd noises at various times, and lead a guy astray unless he knows what to look for.

Tim

 

[AJNY]

Use Redline Oil and Royal Purple Filter. Not sure if you can use 5w30 on your engine though. I use this combination in my 5.7 no lifter noise upon startup. However, the service manager at the dealer told me a lot of the V6 engines have lifter noise.

 

[Dale_K]

I have 3 vehicles with the 3.6 Pentastar, a 2012 200 convertible, a 2018 Ram and a 2020 Charger and all of them make a light tapping on a cold start. It only lasts a second and I've stopped worrying about it. I'm pretty sure it's due to the oil draining back into the pan.