Gear whine while turning when cold

[robertd]

'99 2.5L Boxster, 5 speed, 73K miles

Car is new to me (9 months) with an unknown service history. I've been slowly fixing all the stuff I read about here. Thanks for all the great tips and advice :)

Anyway, every morning at the beginning of my 20 mile commute I back out of my driveway, drive 2 blocks to the end of my street, stop, turn right, drive 30', stop again and then turn right again- all without breaking 30MPH. A couple of weeks ago it decided to start getting cold here in middle Tennessee. Coincidentally (or not), when I made those first 2 slow right turns the first sub-freezing morning I heard a pronounced gear whine coming from the rear of my car (sounds like rrrr rrrrr RRRR RRRRRR). The sound was so jarring and unfamiliar I was sure a stick or something was rubbing a tire and pulled over for a dirty knees road-side inspection. No luck and the "grrrrring" sound has persisted each morning since.

I have found that if I am very gentle with my throttle application I can prevent the noise from happening. I have also found that I can not reproduce the sound when I get to work and get all my co-worker car guys out into the cold parking lot for a little pre-work diagnostic session. My first suspicion was a dry or worn differential that was "warming up", thus eliminating the noise after a short drive. Unfortunately there is no "differential" listing in my Bently Manual ;) Any suggestions as to where I should start my search or is this normal??

PS- I've been a Porschephile for 20 years. This is my "starter" Porsche and I'm definitely hooked!! Thanks for making such a great resource!

Edited November 13, 2007 by robertd

[wvicary]

Welcome to the forum. I've no idea what the noise is..... does it only occur turning right and never left?

[Loren]

:welcome:

Like many rear engine and mid engine Porsche's the transmission and differential are a shared unit.

I think I would start by replacing the gear oil with Porsche approved gear oil. As you say you've owned the car 9 months so unless you know what gear oil he/she put in then it is a possibility.

There is a DIY here. Be sure to pay particular attention to the Boxster specific instructions.

[robertd]

Welcome to the forum. I've no idea what the noise is..... does it only occur turning right and never left?

Why would I want to turn left? That would make me late for work ;)

I can create the noise when turning right or left but only when cold, while turning sharply at low speeds and applying moderate power.

[robertd]

:welcome:

Like many rear engine and mid engine Porsche's the transmission and differential are a shared unit.

I think I would start by replacing the gear oil with Porsche approved gear oil. As you say you've owned the car 9 months so unless you know what gear oil he/she put in then it is a possibility.

There is a DIY here. Be sure to pay particular attention to the Boxster specific instructions.

Thanks, Loren. I will order up the tools and lube today in hopes of tackling it this weekend. Two weeks ago I did an oil change and replaced the front motor mount. I scoped out the tranny while I had the car in the air in anticipation that this was what was needed. I will report back the results afterwards.

FYI, here's what my old motor mount looked like :D

Edited November 13, 2007 by robertd

[robertd]

Sorry for the delay with the update. I ordered the parts back on Nov 12 and they've been sitting in my garage waiting for me to have a free Saturday. Today was the day! Good thing, too because the whining has gotten progressively worse (and less temperature dependent) over the last few weeks. The good news is my average gas milage went up 3MPG as I have nursed the car back and forth to work ;)

I got the car in the air...

...removed all the parts in the way and got down to draining the gear oil.

The stuff that came out had the consistency of the 0W40 I put in the motor. No idea what it was but it wasn't right. There were some expensive looking metallic particles stuck to the drain plug...

...and some glinty stuff in the drain pan (panning for gold anyone) but nothing too major (I hope).

After rigging up a pressure filler from my MityVac I was able to get 2.4qts of Swepco 201 80/90 in the transaxle and only about 15ozs on myself.

I cleaned about 2 pounds of oily dirt off the transaxle fins and buttoned everything back up. The initial test drive in 50° weather produced no signs of gear whine while turning or accelerating from a stop (which it was doing yesterday in the same weather). The shifter feels a bit stiffer but that's OK since it was pretty sloppy before. Hopefully all is good. Sounds like we're going to get another cold snap here in TN soon so I'll let you guys know if the problem is truly fixed.

Proud of all my hard work I decided to treat the Boxster to its first bath in a month. "She's purdy paw. Can we keep her?"

[robertd]

Several cold mornings in a row this week (11° yesterday!). Gear whine is gone :) The Swepco takes a a while to get up to operating temperature so the gearbox is a bit balky for the first few minutes. Once it warms up all is good. Now I just need to replace my sloppy shift linkage <_<

[WC13]

Several cold mornings in a row this week (11° yesterday!). Gear whine is gone :)

robertd,

I am experiencing this exact same thing. I was planning on taking care of it this weekend or next. About how long did it take you to complete this project?

Thanks!

[Chris_in_NH]

I am experiencing this exact same thing. I was planning on taking care of it this weekend or next. About how long did it take you to complete this project?

I have this exact same problem too with my '97. It has been happening for years. Usually only when it is very cold out, and mostly when turning right. I have described the problem to others as sounding like one of those zip-cord toy cars where you pull the zipper-cord quickly to launch the car.

I just changed my transmission oil about a month ago (it took about 2 hours as the fill plug on my '97 was a bear to unscrew) and hoped that the noise would go away, but it didn't. I am going to check the motor mounts and shift linkage when the weather gets a little warmer. The good news is that this has been happening for at least the last 5 years (that I remember) and my car is still going strong, and on the original clutch, for 130K miles.

I hope we can find an answer to this. It is puzzling.