JoesCayenneS

Hey guys,

Months ago, I would hear a very faint grinding / rubbing sound every once in a while while making slow right hand turns. It seemed to happen more when I had someone else in the car.


Yesterday, the noise got way worse, grinding and squeeking sound when making right hand turn. At that time, I noticed I picked up a screw in the tire and the tire was low (maybe happened the night before). It had 15lbs..and I went to go fill it up to spec, and the noise went away.

Bushings? CV? Bearings. What would be effected by the lower ride height of the one tire? I do feel the noise through the wheel when I heard it.
Sounds fine now.

I'm just looking for ideas before I go to the indy. I am pretty handy, just need to know what I'm getting into.

Thanks,

Joe

deilenberger

Actually - the the higher rotational speed of the deflated tire. You're making the limited slip differential work much harder, and if the fluid is getting old - it will get noisy. Grinding/squeeking sound like the differential.

Fix - change the fluid.

BTW - friend with a new Caddy Escalade was blowing through center diffs every 6,000 miles. He asked me after the 3rd one if I had any ideas. I asked if the tires were all the same diameter? Turns out the rear tires had been replaced for some reason when the fronts had about 1/2 wear on them. That was enough difference in speed to burn out the center diff. He suggested this to the dealer - the dealer replaced the front tires - he's gone another 20,000 miles now without a problem.

With full-time 4WD you have to keep the tire diameters within manufacturer's specs.. and I'm sure Porsche has those spec's listed somewhere.

Edward 96 Viper GTS

what is the correct tire pres for 275/45/19 p zeros? front? rear?
tia
ed

red95993

The sticker on my door says 38 front, 42 rear for average loads, 38 front, 49 rear for five people and full load for 19 inch rims. I usually run 35/38 for a better ride...what does the door sticker know!

JoesCayenneS

Wow, that makes great sense. It did seem to happen when it gets hotter out, which would explain the fluid being old and dirty. I'll get that fluid on the front diff changed today.

I'll keep you posted!

Thanks,
Joe

JoesCayenneS

Hey guys, well I drained the old fluid. It was nasty and smelly.

Added new Mobil 1 75-90w LS fluid. At first I thought it fixed it. Car drove great.. soon enough after 15 minutes, hot day.. the noise started again.. Only when turning right with foot on accelerator. I can feel it in the wheel and it sounds like scraping (almost like the belly cover scraping..but its not).

No noise turning left, or going straight. No noise first 15-20 minutes of driving. I can't see the new fluid braking down and heating up that fast. How about PS fluid? Could that cause problems? I did add a small amount of Lucas PS additive.. (thought I had power steering whine..but its just a normal Cayenne)
when I first got the car (30k miles ago). My South Flordia P mechanic is MIA and I didnt want to chance a new Mech until I had an idea of what this is..

Sorry to rant..

Thanks,
Joe

SCOTITUDE

wheel bearing or cv joint

JoesCayenneS

Well, I'm taking it to the indy tomorrow..

Been thinking about diff failures..transfer case failures and I started thinking about low fluid situations..

Coolants pipes broke 1 year ago today (my Birthday weekend )

Leaked all over.. I did the repair, but still had a small leak for a week or two. Fixed all the coolant leaks, new coolant tubes, all good.

Well, last oil change we thought we saw a RMS leak. Looked like Oil, but could have been dirty Red oil. After doing more research, it looks like it could be a Torque converter seal? Could the slowly leaking fluid cause the driveline grinding I'm hearing while cornering in 90F temps?

If so..I'm thinking around $1k I heard (and I get new Trans Fluid/ Filter)..which is better than a diff!

Thoughts before I go to the Indy? I'll let you know what they $$ find out.

Joe

SCOTITUDE

torque converter seal is residual damage from leaking coolant pipes.
been thru whole front diff with same symptoms as you have. i put in newer unit. its not fun. it was one of the noises but not the grinding noise. solved minor issue. ptech advised front diffs do get noisy as they get old but only fix is a new unit. if your front wheels are tight during a bearing test id go axles/cvs.

JoesCayenneS

Scott,

Any way I can keep the transmission topped off as a temp fix to not cause any internal damage? I know there is a fill hole..

I figured all that nasty coolant did a number on my seal. It was all over.

I'm just trying to figure out what to fix first without causing the most damage.

Thanks,

Joe

SCOTITUDE

leave the diff for dead last, there is nothing inside that can really go bad.
is the seal actively leaking? clean it all up and subsequently shows signs of leaking?
if yes then u have to change the seal. i think its a tranny out job. and shes a monster box. not good.
if your going to spend some $ get it done.
have tech check front bearings. no wheel vertical movement. hold wheel 12 and 6 oclock. try to move in and out. spec is no movement. (just in case u didnt know. ) if they are tight id go to axles. if you wanna be sure and do a while ur in there just pull off all front susp and do bearings and axles. you have to pull off same parts. just go further and do the bearings.
id do the seal first. u dont wanna end up replacing a trans or have to constantly get under the p!g to fill it up.
bearings axles make noise but arent gonna explode and cause any damage. they just gonna make noise.
i had axles rebuilt locally. iirc, $100ea, with new cv's . bearings were like 150/set? labor should be 4-6 hrs?
maybe a G for whole job?
seal job i cant advise. never did one.

JoesCayenneS

Just to update.

Noise was coming from the rack area. I topped off the fluid, ran it for a bit. Sucked out fluid from under cap, added again. Noise never came back. Hot days, people in car...no more grinding in wheel! Then, I stupidly did the process again and now it's back. I am thinking I have some air in system..or possibly a bad PS pump? No leaks from the PS system..

I will bleed the system and make sure it's topped off. Now I know it a PS noise.

Still doesn't fix the tranny seal ..

Oh well.. Learning more about it everyday. Thanks for the suggestions.

Joe

pokerjarvis

How do ya add tranny fluid?

Frutti_pig

Bump.

Any more answers on above question. Also is there a life expectancy on the tranny fluid?

Cheers
FP

Just found the below info while searching the forum, but when do you need to change tranny fluid?

"The transfer case does take ATF. I swapped out my front & rear Diffs with Redline 75w-90 gear oil and the Transmission & Transfer case with Redline D4 ATF. The Diffs fluid seemed to be fairly worn, as their have been a few Diff failures I can understand, stock fluid may not be up to snuff. The Tranny & Transfer case fluid didn't seem too bad as far as smell & clarity. With the Tranny fluid that is a complete drain and removal of the pan to replace the Pan gasket, I let it drain overnight and it took about 8~9qts.
For the Transfer case (.75~.85 litres) the manual calls for an ATF meeting Esso LT 71141 spec which the Redline D4 and many others Synthetic ATF's do. For the Tranny the book says Esso JWS 3309 fluid,(8.5~9.0 Litres) which once again overlaps many of the new and better Synthetic ATF's such as the Redline D4. Amsoil and others also have Synthetic fluids meeting this requirement as well Toyota, and Mobil has a fluid they specifially call the 3309 which many believe is the OEM fluid, I just personally believe a full Synthetic like Redline is better. I think as long as you use a good top name 3309 fluid with a new filter you will be doing your tranny & transfer case a favor in the long run as the fluids do break down, and prolonging the life of our vehicles with a little maintenence is what we here are looking for. If your looking costwise, the Mobil is definitely cheaper than a full synthetic."