Rumble after shut down

[pvasilje]

OK, I'm driving my brand new 2008 6.4L truck. I drive it 10-15 miles and then let it idle for a couple of minutes before turning off the key. It makes a somewhat obnoxious rumbling sound for 5-10 seconds right after turning the key off. I've been lead to believe that this is my turbo winding down. Has anyone else had a similar experience? The truck was not under load, driving easy and idled for a couple of minutes before shut down. Does this sound like the turbo winding down and should it be doing that in this situation? A 7.3L diesel that I owned for 11 years never did anything similar. It really is an obvious rumbling sound.

[dzchey21]

Pretty sure your just hearing the turbos. One turbo is a variable vane turbo so it spins a little faster at idle than the average turbo.

[forcefed6.4ford]

just the turbos. Nothing to worry about.

[babryan]

If it is kind of a sucking/rumbling sound it could be in active regeneration. Mine does this when in regen and i let of the accel and when I shut off the engine. If you have all updates you should see a message on the display "cleaning exaust filter". If you don't have all updates, you will need to go into the diagnostics display and the last status will read "cleaning exaust filter".

[DavidPhillips]

The sound is heard more if the truck is at high idle. At low idle I don't think it should be making as much noise as your saying.


10 seconds is an extremely long time for a turbo to be winding down.

[jimd1050]

Yeah, my '08 does it too... but it's more like 3 or 4 seconds. It does sound obnoxious though!

[pvasilje]

Thanks guys. It could very possibly be less than 10 seconds. It may have seemed longer to me because it was so obnoxious. Very possibly could have been 3-5 seconds. It does sound like we're talking about the same thing though. David, I'm not sure what you mean by high vs. low idle. After stopping I let it sit for a couple of minutes to cool down the turbo as I always do (I don't have an EGT gauge to tell me when it's cool enough so I play it safe.). I would assume that it would be in low idle.

[pvasilje]

It definitely is obnoxious. My wife is unually oblivious to anything going on with the truck. Even she looked over at me the first time we heard it and wanted to know what in the world was that??

[DavidPhillips]

The old programming would idle high if it was in regeneration mode. This would cause a lot of the noise to be heard. However if it is cold enough to set a high idle or the truck is hot enough to set a high idle then the noise would be the same.

It must be something making yours different than mine, at normal idle around 725 RPM I don't hear it at all. If you want to see what I'm talking about turn it off at 1400 RPM.

[billybadd]

Mine does it too. Almost sounds like a girgle?