Poll: Diesel like noise clutch determinative?

Okay, I have a thread going on 2nd Generation Tacomas entitled "Rattling Type Noise (Diesel Sound)". Have had a number of response demonstrating (if we are in fact all talking about the same noise) that a few 5 speed manual transmission tacos have a mild diesel like noise coming from what appears to be the transmission/bell housing area. It almost sounds like gears turning or a slight rattle. It is noticeable in idle. It is a little more noticable with the A/C on. No one on that thread with a 5 speed has responded that they do not have the symptom.

The issue is that the noise goes away when the clutch pedal is depressed and returns when the clutch pedal is up. Trying to determine if this is a problem that needs fixing, and if so, what is the fix.

Poll Question: Does your 2nd generation 5 speed while idling have a similar noise that goes away when you depress the clutch pedal and comes back when you let up off the clutch pedal?

 

I'll listen close tomorrow, but no noise that I know of. My sounds are a/c clutch kick-in, and rear spring "clacking"

 

yes. hate it sounds broken then when i accelerate its slow making it even more embarrassing haha

 

yep.

 

most of the time the noise you described and when it comes and goes when you say is the throwout bearing.but like i said that's what it is most of the time

 

Mine was really loud in the summer of 08'. Now at 53,000 miles the noise has completley gone away.

 

Mine at 29k miles is loud. Really bad when I'm at a drive through picking up food.... I'll check to see if it goes away with clutch. I know it goes away with RPMs.

 

On my other thread, referenced above (I wish I knew how to link it here), one guy that was having the noise had his throw out bearing replaced, and he said the noise came back the next day.

 

Yes.

This noise happens when the clutch is OUT with the transmission in neutral. It's noticeable at idle and goes away if you increase the revs. Even more noticeable if you run the A/C - but only because that extra load drags the idle speed down a bit. (It's NOT the A/C compressor or accessory belt).

It sounds like loose gears spinning/rattling. I posted in the other thread already, but one thing I forgot to add is that when you push the clutch in, the noise doesn't just immediately "go away"... it's more like it "winds down"... as whatever's spinning slows to a stop. When you let the clutch back out (tranny still in neutral), you can hear it spin up again.

It's definitely something spinning in the transmission. I'm betting it's the input shaft/bearings. It's NOT the throwout bearing - because that comes into play when the clutch is pushed IN.

My only question is - is this something defective or just the nature of this transmission?

 

I also hear this noise - the same thing, A/C on, louder, clutch in, noise goes away. I heard it right away after purchasing the truck, and took it to the dealer right away. The description of problem sounds like a throw out bearing. Went for a ride with a Tech, Service Manager, etc. All heard it, but no answers. They wanted to compare it to another truck on the lot but no other 4 cyl were available. Wanted me to leave it there for a day to check it out again and I never did.

 

It's not the throwout bearing. If it was, you'd hear the noise when the clutch is pushed IN... because that's when the throwout bearing does its job. A guy in the other thread had his throwout bearing replaced and it didn't change the noise at all.

 

I do not believe its the throw out bearing. Its seems more associated to the A/C system to me, and the tech who drove it with me. Get out of your truck and listen to the noise when it happens, if you have not already- you may get a different opinion of what the problem may be. I have gotten used to it, (11,000+ miles later) but it still bothers me, as it does not seem as tight as a Toyota can be. Hopefully we may find out the issue if everyone takes their truck in to check this noise out, and put this issue on the radar with Toyota.

 

Why would the noise stop & start up again when you push the clutch in & let it out if it was anything to do with the A/C system??? All the A/C does is drag the idle speed down a bit - which makes the engine run a little rougher - which makes the rattle a little worse/more noticeable. If you give it a little gas to raise the idle back up just a hair with the A/C on, the noise gets better or goes away completely (just like it does with the A/C off). There was also a guy in the other thread who had his A/C compressor replaced... no effect on the noise. It's not the A/C.

Repeat after me: "It's in the transmission". I'm still betting on the input shaft gears and/or bearings. It may also be perfectly normal.

 

the only time i get the noise is with the ac on.the other day i was in a prking lot in first gear turned the ac on and it made a horrid noise.there may be some connection with the tranny but there is definately an issue with ac.there is no reason it should make that much noise.if the tranny was the problem it would make that noise anytime there was a stain on it ie,starting off and anytime you get on it or lug the motor.

 

Does the noise go away when you push the clutch in? If so, it's NOT the A/C.

 

Not necessarily - because there is a load on the transmission when starting off. The gears are firmly meshed together. If it's just idling, there's no load... there's play in the gears... and they can rattle against each other.

That's really what this sounds like to me. 4-cylinder engines are inherently unbalanced and run rough. These engines have balance shafts to help smooth them out, but they don't help as much at real low RPMs. I think when the A/C load slows the idle down, that rough idle is transmitted into the transmission and the gears of the input shaft sort of rattle back & forth against each other... if that makes sense. I mean... they're meshed & spinning like they should but because of the rough idle, the input force from the engine is sort of pulsing rather than being perfectly smooth - so the gears rattle a bit. That's why the noise goes away when the RPMs go up and the engine smooths out (either because you turn off the AC or just rev the engine. I'm starting to think this really isn't a problem. Of course it could be due to too much play in the bearings and it's the input shaft itself rattling due to the rough input too. If the bearings are truly BAD, then this noise should get progressively worse as the bearings deteriorate. I thing I'm just going to take a "wait & see" approach for now and see if it gets any worse... of if Toyota issues a TSB for it. If there's really a problem, it should fail long before the 60k-mile powertrain warranty expires.

 

it only happens with the ac on,it is still there with the clutch in just not as loud.i'm not saying it is not clutch or trans related you just can't rule either one out for sure.just that mine seems more ac related.i spent 10 years in a shop and nothing surprises me.i've seen alot of weird shit and i we will all just have to wait and see till someone figures it out.

 

Did anyone get out of their truck and listen? I am not sure why, and it makes no sense, but with the clutch in, the noise goes away or decreases with my experiences. But outside the truck, the noises seem to point to the A/C system..

 

The noise in mine goes away completely when the clutch is pushed in all the way. In fact you car hear it sort of "wind down" - and then when you let the clutch back out, you can hear it "spool up". I'm absolutely convinced it's in the tranny.

I have not stood outside the truck and listened to it - but I have been right up beside the brick wall of a fast food joint in the drive-thru line with my window down - and could hear the sound loud & clear as it bounced off the wall. It went away completely when I pushed the clutch in. Came back when I let it out.

It's possible we're dealing with more than one problem and I only have the tranny issue. If you're convinced yours is A/C related, it very well could be a bad compressor or something. But I stand by my opinion that if it goes away when you push the clutch in, it's NOT the A/C.

If you're still getting a little bit of noise when you push the clutch all the way in, try putting the transmission in gear. If the noise then goes away completely, then the transmission is definitely the source. The reason being the input shaft (which is what I think is the source of the noise) may continue to spin slightly with the tranny in neutral and the clutch in (especially if you don't push it all the way in). If you put it in gear, the input shaft CAN'T spin unless the truck is moving - so that will rule it out.

If you're still hearing the exact same noise with the clutch all the way in and the tranny in gear, then the source of the noise is something else.

Also, the fuel injectors make a fairly loud clicking sound that is similar to this. If you're outside the truck with the hood open, you'll hear them pretty clearly. Don't confuse them with this issue.

 

There appears to be a common theme so far. The ones responding with what appears to be the same symptom are 2008-2009 models (manual 4 cylinders) (except one 2005 model on my other thread). I wonder if something was changed in 2008 or if simply there are no 2005-2007 manual 4 cylinders on TW that have seen these threads or care to participate.