When I shut down my truck after it's been running for a while, I often get this buzzing sound coming from somewhere up front, like the engine bay or right at the base of the windshield where those air ducts are, or something... it lasts about 2 seconds, and starts higher pitched and it goes to lower pitch, like something is slowing down. I don't know what it is or how to fix it. Any ideas?

 

Usually the EVR solenoid bleeding off vacuum.

Harmless.

Steve

 

Kind of annoying though, and the truck didn't do that when it was new. Anything I can do/clean/replace to fix it?

If it was what you mentioned, does that mean that if I don't have my environmental control system on at all, like the blower motor not running, that it will not make the sound? Or will it make it regardless?

 

my truck makes that noise.

 

You can pull the EVR solenoid's cap off and clean it and the little filter on top.

Of cousre, you need to correctly identify the source first. I just gave you the indentification of the most likely suspect. It's up to you to actually LOOK UNDER YOUR HOOD!

Steve

 

Steve, your knowledge in this section is amazing. What are your credentials?

 

yeah, i've always wondered what's under that big flat piece of metal i look over while driving

seriously though, thanks for the starting point. i don't think being able to identify EVR solenoids is exactly common knowledge though. i actually have no idea where it is, what it looks like, or what it does.

 

I'm like Yogi Bear... "Smarter than the average bear!"

I've made my living analyzing and repairing complex electro-mechanical systems for thirty years. I got fed up with auto dealerships about ten years ago and decided I would be self-sufficient in servicing my own vehicles, so I applied my professional experiences to automotive systems. Now it's just a hobby and a time-kill activity.

Steve

 

Well, locate the EGR valve itself. It's a flying-saucer-shaped unit that is connected between the intake and the exhaust. Locate the single vacuum line on it, then follow that vacuum line to it's other end. Now you've found the EVR solenoid.

See if the noise is coming from it when the engine is turned off.

Steve

 

I can do that. I'll give it a shot and let you know what happens!

 

I located the filter and yes it seems that is where the noise is coming from. Can that little black plastic cap thing come off so I can clean inside? What should I do to clean it all up or fix it so it doesn't make the noise anymore?

 

And if the noise is coming from the EVR ( Steve's not your average bear - That cracked me up man )-

Anyways - easy way to confirm the EVR is humming a tune is by putting your hand on top of it while it's making the noise - It vibrates

 

My truck made a buzzing sound similar to what you have described. A new pcv valve made mine go away.

 

Noisy PCV valve usually show up during engine operation. After the engine shuts down, there isn't enough vacuum left to make it buzz.

Steve