"Rattling" type sound during acceleration...?

[fkovalski]

I get a "rattling" type sound during acceleration. It literally sounds like a spray paint can being shaken real fast... almost "machine gun-like" sound. The sounds seems to sounds as if it is high up on the dash board behind the radio.



The rattling seems to happen during acceleration, then it tends to go in and out as I maintain speed at around 2,000 RPM. Truck the one in the sig with 84,xxx miles.



Anyone else experience this? Any ideas on what it is?

 

[C.Solomon]

Sounds like maybe timing rattle
almost detonation type sound?

 

[HBarlow]

That can be and often is caused by a failing FCA (fuel control actuator). It is about $150 from a Cummins dealer or Geno's. A small black device attached to the side of the injection pump with three small metric allen screws IIRC.

Replacing it without extensive troubleshooting and proving is a good bet because most owners report eventual failures of their FCA. A common failure item.

 

[GCroyle]

Is this noise related to the RPM and load? I might have this noise, accelerating in 4th and 5th makes the noise especially at higher RPM just before shifting and then shifting to 6th RPM drops, load is applied and noise goes away.



Anybody got an issue number writeup on FCA's?



Interesting.

 

[HBarlow]

One of the symptoms experienced when an FCA is failing is what sounds much like ignition timing and low octane caused pre-ignition or valve rattle in a high compression gas motor.

 

[Prairie Dog]

I don't put many miles on my truck (76k now) but I just got back from a week long trip and I thought that noise was just the NV5600/clutch noise but on the other hand, it seems like it has gotten a lot louder and is showing up more often. Especially if I'm lugging it a bit.
If it's just timing rattle would it go away if I put the Smarty Jr, back to stock?

 

[Bob4x4]

If you do not have timing issues check your Rail pressure. Extreme rail pressure will cause rattling that sounds much like a gasser on very low octane gas

 

[Prairie Dog]

If you do not have timing issues check your Rail pressure. Extreme rail pressure will cause rattling that sounds much like a gasser on very low octane gas

Are there failure modes that can cause it to be too high? I thought it always failed by going low but I don't have much experience in these things. .

 

[fkovalski]

I had in to the dealer... they said this rattling is normal. I brought o their attention the FCA. They say they deal with very high volume numbers of Cummins diesels in their shop and have never had this as an issue.

 

[Prairie Dog]

Dealers like this are priceless because they make it clear that they have no idea what they're talking about. So at least you know where you stand.

At 2000 RPM's my engine is almost silent - certainly nothing that would be described as a rattle or machine gun type sound.

FCA failures are common. You can read endless posts regarding the symptoms and how this part corrects the problem.

They clearly have very little experience with, or knowledge of the Cummins IMO.

 

[cerberusiam]

The next time you hear the rattle push the rpms up to around 2500 and see if quits. Cold my rattles like crazy unless I push the rpms. Backing the timing down helps but doesn't completely eliminate it.



Its the nature of a diesel to have that type of injection rattle and as the injectors wear they tend to get noisier. The other thing you want to check is the fan support bearing and the upper idler pulley. When these go bad then will setup a rattle at idle and low rpms that is close to an injector rattle in sound.



I chased the same thing for a long time trying to track down the noise and it ended up being the fan support bearing. Spin it by hand it makes noise and feels rough it is bad. Changed that out and a LOT of what I thought was injector noise disappeared. The rest is just normal combustion noise I can control with timing.



Could an FCA cause it? Maybe, anything is possible. However, a failing FCA usually manifests with surging, dead spots, rough idle, etc, if it is getting bad enough to really impact the fuel delivery.

 

[JJPage]

I get a "rattling" type sound during acceleration. It literally sounds like a spray paint can being shaken real fast... almost "machine gun-like" sound. The sounds seems to sounds as if it is high up on the dash board behind the radio.



The rattling seems to happen during acceleration, then it tends to go in and out as I maintain speed at around 2,000 RPM. Truck the one in the sig with 84,xxx miles.



Anyone else experience this? Any ideas on what it is?

Have you got a fueling box on your truck? When my original TST was faltering, my truck would rattle like crazy, not so much while accelerating, but just after. Like if I took off from a stop, everything was normal until my speed started catching the fuel I was applying, then it would sound like an AK47 going off under my hood.



At first it just did it before I reached operating temperature, just before the TST totally crapped out, it did it all the time. Since Mark @ TST rebuilt my fuel box all has been fine.

 

[JMarketos]

I generally agree with all of the above.
One other ancillary possibility- by any chance do you have a mechanical boost gauge installed ? Sometimes the diaphragm in the boost gauge will rattle when under significant boost (mine does).

 

[fkovalski]

OP here... Thanks for the input, I will follow up to some of the questions & comments:

Is this noise related to the RPM and load? I might have this noise, accelerating in 4th and 5th makes the noise especially at higher RPM just before shifting and then shifting to 6th RPM drops, load is applied and noise goes away. ...

I notice the rattling not under any real hard load. It occurs mostly when applying the accelerator in a "maintaining speed" situation.

One of the symptoms experienced when an FCA is failing is what sounds much like ignition timing and low octane caused pre-ignition or valve rattle in a high compression gas motor.

Yes, it kinda' sounds like you describe!

... Its the nature of a diesel to have that type of injection rattle and as the injectors wear they tend to get noisier. ... .

This is what the dealer alluded to.

... However, a failing FCA usually manifests with surging, dead spots, rough idle, etc, if it is getting bad enough to really impact the fuel delivery.

I have none of the symptoms you describe... But did have a distinctive rough motor at 900 and 1800 RPM. The dealer recommended running a bottle of "Diesel 9-11" in the fuel. I did this and the roughness has subsided considerably.

Have you got a fueling box on your truck? ... .

I do not. The engine is totally stock.

I generally agree with all of the above.

One other ancillary possibility- by any chance do you have a mechanical boost gauge installed ? .

I do not.



I will read up more on the FCA issue as mentioned. Does anyone have a link handy that they can point me to?



Thanks,

-frank.