Engine exhaust clicking noise 2019 FL Chassis

[redbaron73]

Today I was doing a walk around with the engine running. Not my usual routine, but I had forgotten to do the walk around prior to starting the engine.

At the rear I heard a clicking noise that was on a 1.5second interval. It sounded like a relay engaging, but loud enough to be heard over the sounds of the engine.

I opened the rear chassis battery bay door and was able to determine that it is coming from the exhaust canister, where there is a wire harness entering the top.

I have no unusual temps, nothing showing error, and possibly this sound has always been there, and my break in standard routine is what brought it to my attention.

Has anyone else observed this noise? Any idea what this canister contains that could be making such a routine and noticable clicking?

Another way to describe it is the sound of the ac clutch engaging/disengaging every few seconds.


This is a 2019 freightliner with 450ISL side radiator. 11k miles.

[Ricci]

Hi Redbaron - I have the same ticking. At first it had me concerned but like your's, it has no effect and appears to be part of the package. You can not hear it on the drivers side or from behind. Only noticeable from the passengers side and easier to hear with the bay door open. Sounds like we have twins, even with the different chassis. I'm assuming that it is something to do with DEF injection as it doesn't do it when not at normal operating temperature.



Tom

[redbaron73]

Thanks! It must be an epa2017 item. I Still have a lot of learning to do.

Originally Posted by Ricci

Hi Redbaron - I have the same ticking. At first it had me concerned but like your's, it has no effect and appears to be part of the package. You can not hear it on the drivers side or from behind. Only noticeable from the passengers side and easier to hear with the bay door open. Sounds like we have twins, even with the different chassis. I'm assuming that it is something to do with DEF injection as it doesn't do it when not at normal operating temperature.



Tom

[ChrisFSB]

Originally Posted by redbaron73

Thanks! It must be an epa2017 item. I Still have a lot of learning to do.

Yup, seems to be coming from the area where the DEF tank is located. Same noise on my 2020 DS (FL).

Thanks for posting and the reassurance this is normal.

[MikeyG]

Red Baron:
Me too. Usually only when the engine is cold.
Seems to disappear when the engine is at normal operating temps.
No worries.
Mike

[FLSteve]

redbaron73,

Mine does the same thing.

FLSteve

[Ann n Gene]

Yep, got the same noise on my 2020 NA.

[CaptainGizmo]

Same on my Spartan.

My diagnosis, aka assumption, is that it’s the DEF metering system; injection of DEF.

I just did a Google search and this is all over the net in every diesel imaginable.

[Hmf23]

Guys that clicking noise is most likely the dosing meter for the DEF system. We noticed the same clicking on our newest Fire Apparatus and thats what the shop foreman stated.

[Wild Card]

DEF injection solenoid

[ScotS]

The last two posts are correct. It's the engine after treatment doing it's thing injecting DEF.