Taco sounds like a sprinkler

So last weekend I replaced all of my vacuum lines on my 01 3.4 Tacoma. I’ve had it about a year now, there’s always been a slight vacuum leak noise but I’ve never been able to find it, never any idle problems or anything that would come from a vacuum leak so I just left it. But as I’m prepping to replace my trans due to dreaded pink milk shake, I’ve been going through and doing a tune up on a lot and decided since the vacuum lines are original and cracked at the ends why not replace them with silicone. Well right after doing this, there is now a very prominent vacuum leak, no codes but it’s audible from the cabin. Truck starts fine and runs fine, but after about a day driving to work I noticed it had an almost sprinkler like sound,Tss tss tss tss if that makes sense, while driving, my guess is exhaust manifold leak since it sounds like it’s going with the combustion of the engine. Also as I accelerate it sounds like there’s a line just open, which there isn’t I’ve triple checked every single line, even ones I didn’t touch. My first thought was maybe my IAC needs some love and is having to force air through a clogged system. Haven’t had a chance to tear into my throttle body yet but I disconnected air cleaner hose and my throttle body could use a cleaning but there aren’t any gaps, just a little dirty. I don’t see the correlation from what I’m hearing to how my truck is driving. I haven’t had any issue with anything except gas milage. I have almost always gotten 15.8 give or take .5 or so. But after doing my vacuum lines I got 14.6. Truck runs fine, other than audible noises I now hear after doing my line, which I know aren’t normal. I had a 98 supercharged 4runner before my tacoma, I’m fimiliar with 3.4s but I am not able to find out what it is. My sister also has a stock 3.4 99 4runner and hers sounds pretty normal. Any help would be appreciated.

 

I would start by cleaning the MAF sensor.
Then after that do a reset of the ECU by removing the battery cable overnight

A dirty MAF will effect all types of stuff.

Clean the bulb and the two resistors.
Use the correct cleaning spray with the ignition off or keys out of the ignition

 

The MAF is only a year old, I had to change it when I bought the truck. I haven’t checked it yet though, I guess it wont hurt to give it a clean.
I would assume that it wouldn’t be the cause of anything I’m hearing, or the fuel milage issue since everything showed up the day after I changed vacuum lines.
I’ve only found one forum that someone says they had the same sound but no answer to what it was, so I will keep the thread updated as I dive into it, for anyone else who may have the same issue. Might try to get a video and post a link

 

From your description it sounds like an exhaust leak, maybe an exhaust manifold gasket that’s leaking on one cylinder.

 

Without hearing the noise, I think you could hear a leak around the brake booster when its running so you may have already ruled this out. If not, since the noise is audible from the cabin, I would disconnect the vacuum line that goes to the brake booster and plug up the end with some metal object. I usually have a some tool around that serves as a vacuum tube plug. You won't have power brakes, but it might rule out a leak that is associated with the brake booster.

When I find a vacuum hose that has split open on the end from age and I need to stop the leak immediately, I use silicone repair tape. I've fixed or enhanced risky hoses with a good wrap of silicone tape until I can get an OEM replacement. I think the tape is sold in most hardware or parts stores as "Rescue Tape. The tape does not contain glue and must be stretched during installation. It puts a silicone coating around an aging/cracking rubber hose as a temporary fix until you can get a hose replacement.

https://youtu.be/hvXLc590ocQ

 

This is a great idea. That stuff is awesome but hadn't thought of wrapping up those little split vac hose ends with it. Easy way to help further diagnose stuff without buying a bunch of unnecessary vac hose.

 

For sure. I actually used it for just that last weekend. You can see where I use it to fix the weird shaped vacuum line that runs behind the brake booster in this video. Then to provide extra protection on another line that runs into the rubber air pipe. Its great for wrapping old worn electrical conduit and reconditioning the injector wiring harness.

See if you can spot the locations where I use it in this video.

https://youtu.be/MtFbMO6CoZs

 

That’s a good idea, didn’t think of that. But from what I can hear it sounds like it’s coming from the passenger side, almost right behind the throttle body, which makes me think IAC but it sounds like an exhaust leak from the almost “revolving” sound as it goes in timing with the revelation of the engine. I’ll try to get a video of the sound and post it up today or tomorrow.


I am going to try to do a smoke test this weekend, will post some photos of a rigged up smoker, and post the results. Hoping it’s not an exhaust leak, or perhaps my valve clearance.
I have noticed a tick, louder than the normal 3.4 valve noise, coming from about the middle of the valve cover on the driver side. But I’ve heard it for a couple months now and nothings been effected so far, and nothing else has shown up until doing my vacuum lines, so hopefully It’s not my clearance and need to do a HA on the valves. Even though I need to do my leaky valve covers.

man that’s one of the cleanest 3.4s I’ve seen haha. I noticed you had it on the hose from the air cleaner, that’s one hose I still need to replace, But so far I think I ruled that one out as being the source.

 

I couldn't get my eyeballs to look for anything else as the all the clean shiny stuff was far too distracting

 

Didn’t have a chance to get to my throttle body and do the smoke test but I recorded a video of what sounds like a clearly open vacuum leak, didn’t hear the sprinkler sound this time, it usually only shows up after about 5minutes or driving.

https://youtu.be/SwNLsximOJs

I didn’t have any of this before doing my lines but I haven’t gotten to the ones connected to the IAC yet since I’m waiting for the hose to come in, so maybe it could be one of those.

also, question on exhaust leaks, this may sound stupid but could an exhaust leak cause excess moisture in the exhaust? I’ve noticed in the past maybe month or so that there seems to be more water than I’ve ever seen from it, not like it’s dumping out but more than it used to and more than my old 4runner. I smelled it and has no trace of smelling like coolant nor is there any smoke. Just excess water it seems, my muffler now has a small hole rusted in it and is leaking water. This only showed up in like the past month. Maybe I just never really realized this before but I can’t help but want to fix it haha

the pic is after about 2mins of cold idle, water started dripping, same with muffler

 

i loathe weird sounds never heard before
mine are pancaking anymore it seems
frustrated...

 

I watched the vid and heard the noise, what is that from? A belt and idler pulley or a pulley on a component???

 

I don't know about the year model differences, but my 99 model has a vacuum line that is hidden from view. I have it highlighted below. Just something to check.

 

Water dripping out of the exhaust after start up is normal...nothing to be concerned with unless it does it excessively after being warmed up for several minutes

 

I don’t know what it’s from, that’s what I’m trying to figure out haha, i put my ear up to the throttle body and it sounds like it’s coming straight from the back of it towards the cabin. Sounds like an open vacuum line sucking in, but because it only does it when the throttle is opened I feel like it’s my IAC either clogged or something forcing air through gunk when accelerated causing it to be louder.

I took my timing belt cover off when I changed my radiator and all of my pulleys and tensioners looked as they should. I tried to give them a little jiggle, no play, but hard to say with the tension of the belt on them

I am doing my water pump and timing belt when I do my trans just because I have no clue when the PO did it but everything is still in decent shape.


My throttle body has that same line, I’ve checked them all and they all are intact. I couldn’t get the vacuum hoses off of the other two on the sides and I’m waiting for replacement hose so I can just cut them off instead of fighting them

 

Oh, my hearing sucks pretty bad, so I could be way off. Just sounded kinda like a whirring or something

 

That’s what I figured, all this other shit on my truck is making me find problems that don’t exist haha

 

I don't think its your hearing. I think cell phone microphones like to pick up high frequencies over lows. My videos seem to have a high pitched whine and noise that I don't hear in real life. I've had this problem with other engines and phone microphones.

 

OP do you have a stock intake system? Can you post an image of your engine bay?
To me it sounds like a rush of air when all of a sudden something sees the vacuum as you open the throttle plate.. meaning if that's the case, it could be on the way in

 

Well that makes much more sense. And makes me feel better lolol
I am actually deaf in my right ear from surgeries and left has about 60-70% hearing, many times I'll watch a vid to listen for something to help and I don't hear anything like what they describe so I just shut up
And I do know I don't hear high frequencies very well at all