Hissing Noise Behind Rear Driver Side Tire

I second the problem as snakes....

Seriously, evap is source. Can you hear it while driving?

 

nothing to be fixed. the truck does it automatically. it is normal

 

@hiPSI I cant hear it while driving. The sound isnt loud enough. Only if you're standing next to it you can hear it.

 

@Dkurtz42 so it should constantly be making that noise?

 

I get this is a normal operation
Im more curious about when it occurs and reasoning

 

@a400ryan not sure. My question is, is it supposed to be running everytime? If so I didnt notice it before.

 

There is an evaporator cannister that is constantly venting, cap off, cap on it still vents.
Edit: I am never around my truck while it running. I am in it. I just went out to driveway and mine has a faint hiss when standing right beside the full tube. Like so faint I can move a few feet and lose the sound. I'm not worried about it.
Although it could be my flux capacitor venting banana fumes. Either way, not concerned or even curious lol. It's like listening to your food digest in an absolute quiet room. Who knows what the hell is going on in there...

 

@hiPSI lol thank you! I guess I'll monitor it and see how it goes.

 

You can rule out flux capacitor if you measure Jiggawatts. Gotta test it at speed though, 80+ mph.
Warning though: don’t kiss your mom.

 

I think it’s normal I wouldn’t worry

 

I have the same thing on my 18 AT just noticed it happening yesterday. Temps just dropped into the teen's last few days, could that be a factor?

 

Yes. Gas expands and contracts

 

lol.

 

Normal. Noticed this the first time while airing up my tires after a bit of wheelin. Was a bit freaked out but all my research points to normal.

Also, everyone is wrong about this being a snake problem. IMO, its clearly a rodent problem. Do you have a lot of rodents in your area? You can kill the snakes but theyll just come back unless you eliminate their food source. Kill the rodents and solve this hissing problem for good. May god be with you.

 

I know it’s a old thread, but just found it now, since I started noticing the same sound on my 2020 TRD Sport. Freaking out thinking was some leakage.

So the conclusion is: It’s normal or not?

 

Normal

 

Check for one of these ..

 

I'll trade you for my kazoo rear diff noise.

 

It’s the Tacoma fairies cracking open some cold ones. Totally normal.

 

Reviving old thread. The noise definitely hasn't been there forever. I just did a 2000 mile trip through Baja and noticed it while airing up my tires. Started driving home and the hiss gets louder with speed. At first there was a faint smell of gas so I thought it may be some vacuum leak at the gas tank. Brought it in to Toyota (2018 still under warranty) they couldn't pin point it but did notice it was louder than another Tacoma they had. They dropped the gas tank, didn't find any leaks or issues and suggested it might be the rear diff. Dealership offered to replace rear diff under power train warranty but I was planned to regear anyway.

Since the sound happens when the engine is on and car is parked it doesn't seem like it can be the rear diff anyway.. there wouldn't be any pressure or heat if it's not moving? The only thoughts I had were if the breather was super clogged and it was sucking air through a tiny clogged hole... Either way it really sounds like it's coming from above the fuel tank.

I didn't see any fluids and couldn't feel any air on any hoses (or see any areas where dirt moved)