Suspicious noise

I've noticed a strange noise that continues to get worse. It sounds like a sublte vibration "growl". It occurs mostly when I come off the clutch when I'm in reverse and when I go forward from a stop in first gear. I don't hear it at any other time.

I have a 2007 Tacoma, 6 speed. A buddy of mine told me it could be the throw out bearing. The truck has 98K miles on it. Any idea what it is?

 

Its possible it could be the throw out bearing. A throw out bearing is a part of the clutch system that temporarily disengages the engine from the manual transmission while shifting. Typically when they go bad it will cause the engine to stutter a little bit due to the fact that its not disengaging entirely so even though you're not in gear any more or you have the clutch in, the engine and transmission are still engaged.

I don't know the life expectancy of the 6-speed clutch assembly and depending on how you drive it will dictate that as well. At 98k miles its possible the throw out bearing is starting to go bad.

I had this go out on a 1992 S10 Pickup. If I coasted to a stop sign with the clutch in and left it in gear (2nd) it would cause my engine to stutter and at one point it would stall it if I didn't put it in neutral. I was roughly at 100k miles on that truck when this started to happen just as an example. Ended up changing the clutch and throw out bearing and was good as new.

 

I'm supposed to take it to the dealership tomorrow. I appreciate the reply.

 

U joints are worth a look before ripping out the transmission.

 

Well, the dealership said that the transmission was "going out". I took it to a local reputable mechanic who specializes in transmissions. He said it was NOT the transmission. It was a noise coming from the engine compartment and couldn't determine what it was. He said it could be a loose connection or vibration. He recommended that I continue to drive it. It may stop, continue or get worse. So, back to usual with a noise....

 

Throwout bearing going bad sounds more like a cricket chirping than a grinding or growling noise.

How many miles on your clutch?

 

98K miles... and it only makes this noise when coming off the clutch in reverse and out of first (when in the most torque).

 

Well...that is a bit short of the average clutch life expectancy but they usually only last around 100-150k miles, depending on how you drive and what kind of stress you put on it. It may be getting close to time for a new clutch. The clutch job will replace the pilot bearing, throwout bearing, clutch disc and usually they resurface the flywheel and your issue might exist somewhere within there. If you haven't changed the gear oil yet then that could be something to do, check for any metal particles in the old fluid.

Any other strange symptoms? Difficulty getting into gear, shaking when letting off the clutch, clutch slipping, etc.?

 

If the noise you're hearing goes away as soon as you put pressure on the clutch then it could very well be an issue with the throwout bearing, or possibly a cracked flywheel. Either way, if it's one of those you'll want to replace the whole clutch assembly anyway as it all has to come apart when they drop the transmission to replace one or the other.

 

There were no metal shavings in the oil. I have no slippage or shaking at this point. However, sometimes.. not often I will hear that chirping sound you were talking about. I will continue to monitor it and if it gets worse, I suspect it will be easier to detect what the problem is.

 

Chirping that goes away when you touch the clutch is a sure sign of a bad TOB, if its bad enough maybe it's also causing the other noise you're hearing. Mine was loudest when I would coast in gear, soon as I barely touched the clutch it would go silent.