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What do the Exhaust valves do and why do they keep running after the truck is off?

N

Ninety-9 SE-L

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Ever since my truck was new, I would notice a high-pitched sound and clicking happening around the rear axle. I figured it had something to do with emissions equipment.

It doesn't really bother me, but after I turn off the truck and lock the doors, I noticed that sh*t is happening down there for a good 3-5 minutes.
Even if I hop in my truck to get something turn it on (without engine start), and then I hop back out, the process starts over again.

Today, I decided to crawl under and see what's making the noise and I found these, on on each side just clicking, whining, clicking, whining:
i4yRujR.jpg


Some internet searching and I confirmed they are what they look like, butterfly valve actuators, or more specifically Exhaust Valve Actuators.
I assume they have something to do with the EGR system.

I'm just really curious why they're so busy when the truck is completely off and locked.
I don't know if they're opening/closing continuously or if they're just constantly re-checking their position, but it seems that if they're working so much, they're bound to eventually wear out and fail.
 
Found some info here: 8 million exhaust sensors

The exhaust system is very different from the Gen-2 trucks. There isn't a muffler in the system, only a couple of resonators by the exhaust outlet tip's. The DPF, SCR, DEF injector valve etc. all seem to be newly engineered parts, with one of the biggest visual items being the pipe for the post DPF ERG gasses being taken after the DPF filter.

The valve in the exhaust pipe downstream from the SCR seems to be some sort of electrically driven rotary actuator which I imagine opens or closes a flap valve in the pipe. I don't know at this time what it's use would be other than to give some backpressure to the SCR for some reason. I'm sure we'll find out as time goes on.
Click to expand...
It is a throttle plate to increase exhaust backpressure to make it easier to flow egr from after dpf back up to the engine for rebreathing.
Click to expand...

I still don't know why mine is still making noise long after the truck is off, I may ask over there.
 
Ninety-9 SE-L said:
Found some info here: 8 million exhaust sensors




I still don't know why mine is still making noise long after the truck is off, I may ask over there.
Click to expand...
So does mine occasionally, as did my Gen 2. It is possible (and what I always thought) that temperature has something to do with it since if you're not monitoring your regens you can turn off the truck with 1200+° emission components.
 
I'd understand if it was a temperature thing, but it's just a pair of butterfly valves, I don't really understand why they need to continuously actuate (or whatever they're doing) for 5 minutes after the truck has been shut off.

A great example from a few minutes ago. I've been parked at work all day, my engine hasn't run since 7am. I just went outside on my 2nd break to crack my windows. I put the truck in ACC so the windows would work, then I quickly cycled the button through Run, then Off. Closed and locked the door. I could hear those actuators a-going, they're probably still doing their thing as I write this.
 
DieselFuelOnly said:
One more emission part to fail, mine is squeaking like a SOB.
Click to expand...
I've been reading up. Someone on the 1500 diesel forum got rid of the squeak. The solution was to open up the plastic cover and spray some lithium grease inside.
www.ram1500diesel.com

Squeak at idle near rear end

Hey everyone, I've got a 202 Rebel that I'm hearing a squeaking noise that sounds like it's coming from the rear end when at idle. It happens after engine start and seems more prevalent when in gear at low rpm. Any ideas?
www.ram1500diesel.com www.ram1500diesel.com

They work exactly like an electronic throttle body, all of the serviceable parts are under the plastic cover. It's unlikely the shaft/plate will fail and if they do, you got bigger problems.
 
I've got the gas 5.7, and hear plenty of similar noises. I'll have to take a peek later today.
 
Pcustoms said:
I've got the gas 5.7, and hear plenty of similar noises. I'll have to take a peek later today.
Click to expand...
We don't have those on the gas engines. You're most likely hearing the cabin vents closing. Should happen about 30 seconds after you turn the truck off.
 
Currently have a jeep gladiator ecodiesel. My understanding is that noise is the def fluid being moved back into the def holding tank
 
Ninety-9 SE-L said:
I'd understand if it was a temperature thing, but it's just a pair of butterfly valves, I don't really understand why they need to continuously actuate (or whatever they're doing) for 5 minutes after the truck has been shut off.
Click to expand...
Could it possibly be some type of a cleaning cycle?
 
Well that backpressure valve for the low-side EGR has been in trucks on the road for 2.5 years now and so far I haven't seen a report of a failure. Maybe that's still coming but I haven't seen it just yet.

When it does fail it's going to be expensive to replace probably. The entire design of the exhaust system on those is poor. The bracket up front at the DPF commonly fails due to vibration and heat.
 
My actuator is now squeaking everytime I go from idle to throttle, when i shut off the engine, and even when i open my door after the engine is already off. Truck is 2020 with barely over 50k km. Dealer gold tier warranty won't cover it.

Is there an easy way to delete this part only? Will the truck freak out if i cut it out and straight pipe the section?
 
Gold plan should cover it?? But open the actuator cover and spray some lithium grease in. I had a squeak at shutdown and followed seadog’s recommendation in the link to the other forum.
 
I don't know these systems on the Eco-Diesel, but all Diesel trucks that use DEF and EGR make lots of post shutdown noises. The DEF lines are purged and is usually the culprit when folks ask about the clicks and chirps. The EGR valves cycle, etc. My HD is a cranky noisy little b*tch most times.
 
When I get home tonight I will look it up in the service manual and see what the description it gives. Kinda curious.
Tom
 
What do you need? Mine covers all the engines for 2020
Tom
 
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