Sound from engine when shutting down...

[freekyFX4]

Ok, I don't really think this is a problem, but I just want to make sure. Sometimes, not all the time, but maybe 25% of the time when I shut off my 08 F250 with 6.4L PSD, there is a strange sound. The engine shuts off and there is a sort of "whoomp-whoomp--whoomp---whoomp----whoomp-----whoomp" sound. The sounds get quieter and further apart as something is spinning down. I was assuming it was a turbo, but really didn't know if the turbo would even still be spinning with no load. I usually shift to Park and wait for about 15 seconds before shutting the engine down. It has done this since day one and has not gotten an louder or any more frequent. Everything runs fine otherwise. It's just that sound when I shut the engine off. Thanks in advance for any info.

[rankroddin250]

its probly the fan clutch free spinning after the motor shuts off

[freekyFX4]

Hehe, thanks! Now I will be able to sleep. I had my son turn the key off while I watched the fan spin down, and that is exactly what is making the noise. I didn't realize what a huge fan these things have! Thanks again.

[rankroddin250]

any time

[DavidPhillips]

You need to let the exhaust temp cool before shutting it down. If you have been running hard or towing it could take up to 5 minutes.

[freekyFX4]

Originally Posted by DavidPhillips

You need to let the exhaust temp cool before shutting it down. If you have been running hard or towing it could take up to 5 minutes.

I usually take it really easy coming home for the last few miles of my drive to cool things down. I really need an EGT gauge. I just don't know where to start with that.

[DavidPhillips]

One big difference in this truck from my other one is the turbo boost. It seems to be spinning all the time. Easily hits 20 psi going up a hill at 65mph.

I also try to take it easy as I approach my destination. If I am able to do that I only wait a couple of minutes.

The EGT gauges can be so inaccurate at the lower end of the scale it's hard to trust them. I do however usually shut my other truck down when it gets below 300F.

[metro7100]

Guys the sound you are hearing is the Turbo when the truck is in Regen mode. My truck does the same thing so I took it to the Dealer thinking something was wrong. They advised me when the truck is in Regen the RPM's go up and put the truck under load. When you shut the truck off while it's in Regen it will make the sound everytime.

[gahanna-6.4]

Not to rehash an old thread, but that whoomp whoomp whoomp sound you're hearing is the high pressure turbo variable vanes bouncing open and closed as it relieves pressure back thru the intake. If you watch many truck/tractor pulls you'll almost always hear the bouncing of a wastegate or variable vane turbo as they reach the end of their forward motion at full rpm and back off the throttle quickly.

If the truck is in regen you'll hear it quite often when you back off the throttle while driving as the DPF regen process creates a lot of backpressure on the exhaust system. You can also recreate it by having the truck in park, idle it up to about 1500 rpm and while holding that rpm shut the key off.... whoomp whoomp whoomp.

[powerstrokes only]

Originally Posted by gahanna-6.4

Not to rehash an old thread, but that whoomp whoomp whoomp sound you're hearing is the high pressure turbo variable vanes bouncing open and closed as it relieves pressure back thru the intake. If you watch many truck/tractor pulls you'll almost always hear the bouncing of a wastegate or variable vane turbo as they reach the end of their forward motion at full rpm and back off the throttle quickly.

If the truck is in regen you'll hear it quite often when you back off the throttle while driving as the DPF regen process creates a lot of backpressure on the exhaust system. You can also recreate it by having the truck in park, idle it up to about 1500 rpm and while holding that rpm shut the key off.... whoomp whoomp whoomp.

I agree, my '04 6.0 used to do it too. My 6.4 does'nt do it all the time but quite often. I don't think there is anything to worry about is there?