Rollover Noise / Rattle

[07Wolfie]

Took my '07 Jetta 2.5 5-speed (50K mi) into the dealer a few weeks ago for a thumping/vibraton during clutch engagement. Problem was correctly diagnosed as faulty dual-mass flywheel, flywheel was replaced and problem fixed. However, when I picked it up, I noticed a new noise: when hot idling in neutral with the clutch engaged (pedal up) there was an audible rattling/clattering coming from the transmission. Push the clutch, the input shaft coasts to a stop and the noise stops. Worried that something had gotten into the input shaft bearings and that I was hearing bearing noise, I took it back to the dealership. They replaced the entire transmission with a new (VW remanufactured) trans, and I just picked it up again last night. As soon as it warmed up, I could hear the exact same rattle/clatter while idling in neutral.
I did a little googling, and learned that this noise is pretty common with manual transmissions and is known as rollover rattle...it's caused by gear meshing at low speed under no load, and is generally regarded as benign. The Bentley shop manual for my car does mention that if the transmission housing is not precisely aligned with the block using alignment bushings it will cause this noise, along with troubled shifts (which I have not experienced). I have 2 questions for the collective BITOG intelligence:
1. Should I worry that this noise is caused by slight misalignment of the transmission to the block, and if so, is there a chance that misalignment could cause any other problems that would justify my trying to get the transmission alignment "adjusted"?
2. There are quite a few stories on the interwebs about upgrading MT fluid having a positive effect on gear noise, and I figure this is a no-lose prospect. I'll drain out the OEM G52 lube and dump in some Redline MT90...is there anything else that guys have had success with in quieting down rollover noise? Clover honey, molasses, glue, Lucas

?

Thanks in advance.

 

[d00df00d]

Originally Posted By: 07Wolfie
1. Should I worry that this noise is caused by slight misalignment of the transmission to the block, and if so, is there a chance that misalignment could cause any other problems that would justify my trying to get the transmission alignment "adjusted"?

According to what you posted, the Bentley manual says a misalignment will cause the noise, but it doesn't say a noise necessarily means misalignment. Moreover, as you pointed out, it says a misalignment will also cause shifting issues, which you don't have. I'd say you're fine.

Whether the noise indicates a problem seems to depend on the car. For mine, it's completely normal. For my old '95 Maxima, it meant something was failing. It sounds like your car falls into the "it's normal" camp.


Originally Posted By: 07Wolfie
2. There are quite a few stories on the interwebs about upgrading MT fluid having a positive effect on gear noise, and I figure this is a no-lose prospect. I'll drain out the OEM G52 lube and dump in some Redline MT90...is there anything else that guys have had success with in quieting down rollover noise? Clover honey, molasses, glue, Lucas

?

AFAIK, the only way a fluid swap would affect that noise is if the new fluid is significantly thicker. I wouldn't advise going much thicker than OEM fluid just to get rid of a benign noise. Thicker fluid generates more drag and runs hotter. However, feel free to experiment with fluids in the correct viscosity range.

 

[aquariuscsm]

The noise is completely normal. It`s just the internals of the transmission spinning. Every manual car I`ve owned has done that. As to the fluid,don`t go thicker. It`ll cause shifting issues. I`ve tried that before.

 

[CBR.worm]

Lots of manual transmission (and bikes) make noise in nuetral with the clutch out.

My car makes so much noise it will probably scare off any potential buyers unless they are familiar with these vehicles. It has not gotten any worse since new and is still embarrasing.

 

[mattd]

also could be T/O bearing related.

 

[07Wolfie]

Update: For what it's worth to anyone, I'll post the apparent cause and resolution to my rollover noise. Yes, some rollover noise may be normal, but in my case it only became apparent after the transmission was worked on at the dealership. In fact, it was apparent in 2 separate transmissions after being worked on by the same tech...got me thinking about a common point of failure.
The VAG 5-speed manual transmission in my Jetta has been around in one form or another for quite a while, but it's installation in the MKV A-platform cars required it to be rotated approximately 15 degrees from it's designed position. This means that the "fill" plug is now below the actual fluid level when the transmission is properly filled. VW addresses this with a new and complicated filling procedure that involves completely draining the transmission from 2 separate points, removing the reverse sensor, using funnels and plastic tubes and containers graduated in milliliters and all manner of things that sound like a lot of trouble. Alternately, if you're a VW tech in a hurry, you can just fill it from the old fill plug until fluid comes out and call it good. Unfortunately, this leaves the transmission almost half a liter low on oil, and it turns out that this can cause a relatively loud rollover noise (and God knows what other long-term problems...)
I drained out 1.3 liters, refilled with the proper 1.7 liters, and the rollover noise completely disappeared.

How many times have you said to yourself, "THIS is why I perform my own maintenance."?

 

[scott37300]

Glad you took the time to figure this out. Pretty sad that the dealership doesn't even know the correct filling procedure and possible did damage to 2 transmissions by underfilling.

Did you call the dealer and let them know that you fixed what they couldn't and ask about possible long term damage to the transmission?

 

[07Wolfie]

I didn't call them yet... Not sure if there's an effective way of doing it without getting brushed off as a picky customer or without getting the tech in a bunch of trouble. Plus, I may need to go back there for more work and I don't want to burn any bridges.
On the other hand, I feel guilty for the next guy. Karma is often a female dog, right?

 

[The_Jeff]

Call the VW zone office, they'd be happy to hear about it.

Demand respect or you won't get it. I wouldn't care about having "friends" at the dealership.

 

[d00df00d]

Originally Posted By: 07Wolfie
Not sure if there's an effective way of doing it without getting brushed off as a picky customer or without getting the tech in a bunch of trouble.

If they brush you off as a picky customer for realizing that your transmission was incorrectly installed, you call VW corporate.

If the tech gets in a bunch of trouble, don't forget that he's the one who made the mistake.

 

[scott37300]

You have the TSB of the new filling procedure for your car right? Go in and ask to talk to the service manager and nicely explain to him the situation. I think as long as your not coming across cocky and acting like you know more than them(even though it seems like you do!) they should at least listen to you. Just explain what you found out and that you drained it and it was low. You filled it properly and it solved the problem 2 transmission replacements couldn't. Explain how the problem wasn't there until the first time the mechanic replaced the fluid and was still there after the second time they replaced the fluid. Then you fill the fluid the right way and it's gone. They can't really argue with what VW recomends as the right way to fill it.

Just explain your not there to point fingers, just want to let them know so it doesn't happen to anyone else and ask what damage if any that might have caused.

 

[07Wolfie]

Thanks for the input, guys, I appreciate it. You make great points and I think I'll try to get touch with the service manager via email.