Noise question

My truck with 17,000 miles has recently began making a valve rattle/ diesel engine noise while accelerating usually around 35-45mph or so that last a few seconds. It doesn’t do it every time but pretty consistent. It seems to have started a couple months ago. I know these 3.5 are noisy but any ideas what this could be and if normal? Thanks

 

Could be the Atkinson cycle

 

I wondered about that. It’s always been noisy while idling and I assumed that was the Atkinson cycle just not sure why I’m just now noticing this noise while driving

 

Try a tank of premium gas.
If you shift down a gear does the noise go away?

 

It usually only last a few seconds then goes away while under a load, slight hill or accelerating. I thought about premium gas but I don’t hear a lot about others on here having to use premium so not sure why mine would need it. I may try that just to eliminate that.

 

The 3.5 V6 has 11.8.1 compression ratio so it loves premium.

 

The stated conditions sound exactly when knock would appear.
(spark knock, octane knock, ping - folks call it different things)

Try a tank or 2 of premium from a national chain: Mobil, Exxon, Valero, Sunoco, etc.

Agree, these are very high compression engines, the computer is what allows running 87 octane without knock.

Also, every now and then you have an engine that "doesn't like" brand A fuel but runs fine on brand B of the same octane. Not scientific but it does seem to happen occasionally.

 

Is there any damage that can occur by allowing this rattling/ping to continue?

 

Since the truck is still under warranty I would stop by the dealership service center and have them check it out and document it.

 

Spark knock has no good side effects, only bad - in extreme cases it can burn/melt pistons.

As stated previously this is a very high compression engine, usually the engine management system "hears" the knock and adjusts fuel & ignition to prevent it.

So there is the underlying question: why isn't the computer doing what is required?

Try a few tanks of premium fuel from a different national brand and see what happens.

 

I concur with a name-brand gas. Could be my pea-brain playing games with me but I swear Chevron gas seems to run
better in the Truck than Costco .... seems to get better gas mileage and more umph as well. I stay away from 7-11 type
stuff from now on it's either Chevron or Shell. In fact it's on my to-do list to pump some in today. First of the month, all
bills are paid, credit-card balances are zero - my license to fill it up. I don't run premium just the 87 stuff.

Run a tank or two and see if it behaves better.

 

I run Shell 93 all the time in my 22 SR5. People here say otherwise but I have no transmission studder, quick acceleration and better gas milage. In my defense, it's stock 2wd with stock 245 tires and no hills where I live.

 

OP, if you decide to use 93 octane it will take the second tank before you get the full effect. The computer has to adjust fuel air mixture and ignition timing for the higher octane fuel.

Once you go 93 you won’t go back. My truck performs just like 099 describes above and any top tier 93 is good I use Chevron or Shell.

 

87 all day , everyday since i bought it in 2020. id suggest buying a tesla

 

My 2022 started to do this after my 25000 mile service last month. Makes me wonder what the hell they did to my truck! Or I am suddenly getting shitty gas everywhere

 

I fill my tank with Leaded fuel and if i cannot find it, i add some diesel to my low octane.
runs like a dream!