Niels550

Is anyone getting meaningful numbers on their OBD scanners of the front differential temperature?

I was getting something crazy like -260C and replaced the sensor. New sensor made no difference, still the same crazy number.

Im curious if this is normal or that I may have an issue with either my DME or TCU.

997Berlin

Hi Nils,
I stumbled across your other thread and was hoping you'd find the cause. I have the same issues with my front diff and I am seeing -470 degrees Celsius. Even with a replacement sensor. As you pointed out, it stops after switching to sport mode. I suspect the diff clutch being the problem.

Niels550

I have replaced the front drive with a used one (low mileage) and have exactly the same problem.

The crazy temperature readout can only be because that’s what the DME sends to the OBD scanner. I’m curious if this is “normal”.

997Berlin

I have bought a replacement part (snout including clutch pack) and my hope was that it would be it. Mine started with an oil change of the clutch.

Could someone verify the front diff temp reading on their car, please? I don't think the problem is the temp.

Cheers
Al

V-TT

Al,

What exactly did you purchase, you stated “snout & clutch” - can you please share some details? I was under the impression we could only replace the ENTIRE front diff.

Niels550

Is anyone getting normal / sensible / plausible temperature indication of the front diff oil temperature?

I know my sender is most likely good - a brand new one made no difference..

So I’m trying to figure out if this is simply the DME outputting a crazy number because the actual diff oil temp is irrelevant until it exceeds a defined threshold, at which point the clutch will disconnect power to the front diff.

Or, whether I have a problem with my DME or PTM controller?

997Berlin

Sorry for the delay. I purchased twice actually. It is the snout looking side of the front diff. The part that houses the AWD clutch and that connects the drive shaft coming from the gearbox with the front diff itself. I assumed the same as Niels that the culpritt might be the AWD clutch.




Cheers
Al

V-TT

Where did you buy just the snout? And may I ask why?

Ljt

Hi 997Berlin,

My front differential suddenly had a clonking noise and my mech suspects it's the front differential clutch pack. Can you provide more information how do you purchase this part used or new. Thanks a lot.

LJT

Niels550

Ljt:

Have you tried disconnecting the front wheel drive to see if it actually is the front diff? You can easily do this by pulling the handbrake up one click - this causes the front clutch to disconnect power to the front diff.

And as for where you buy a front drive assembly? Either new from Porsche or any of the P car parts sellers look for them advertised by people who dismantle crashed cars and sell the parts off. You cannot buy the clutch pack as standalone. Bosch (who manufacture the clutch pack) will not talk to anyone. And same design clutch pack by Bosch is used in Hyundai Santa Fe’s amongst many other other cars.

I have what may be similiar problem to you… I get a “thunk” noise when say I’m doing 60mph, take my foot off the gas to coast for a few seconds and then when I put my foot gently back on the gas to resume 60mph, I get the “thunk”. This only ever happens in AWD … if I disconnect the front drive either electrically or by removing the Cardan drive shaft, the problem is gone… it’s a as smooth as silk.

So far not a single person has been able to suggest a fix… to date, I have had the Tiptronic rebuilt (twice), new torque converter, new TCU, new PTM controller, a low mileage second hand front drive assembly, all new engine and transmission mounts and suspension rubbers… all to no avail.

Cheers

niels

Ljt

Niels,

Thanks very much for enlightening me on the matter. Appreciate your knowledge and I can feel your frustrations going through all the fixes but still did not really solve the issue at hand. I had the front diff. replaced with a used unit, but didn't really solve the problem, however adding another clunking noise coming from the back diff. this time at very low speed without depressing on the gas pedal. I suspected the replaced diff. unit was also faulty.

Initially my mechanic hoisted the car and rotated the rear wheels but both front two wheels were not turning at all. Based on the observation he concluded that the front diff. was broken. That was the reason we narrowed down the issue to a front diff. problem. Not sure if we have barked up the wrong tree. Nevertheless, when the replaced used unit was installed, all wheels did turn.

By the way, do you think there is a different in the differential units between a 997 Turbo to a 997 Turbo S? Both units look similar but with different P/N in the US. Apparently, it indicated fitment for cars from 2012 onwards. Mine, a 2006.

Niels, from your experience what do you think is the most likely culprit, i.e. the snout clutch pack or the other half of the differential that is causing the issue?

Many thanks

LJT

Niels550

LJT

First thing… I am no expert.

Have you tried driving with front drive disconnected?… 3 ways to disconnect … (1) Physically remove the Cardan shaft or (2) Pull the E1 (from memory) fuse or (3) pull the handbrake up one click.

That may help narrow down the source of your problem.

In my case, I think the problem is electronic / electrical / software and I don’t know where to go to diagnose it. Yesterday, I put in a new PTM controller and so far there is a huge improvement. So fingers crossed this was the fix.

There is an old saying.. The Ministry of Hammers thinks every problem is a nail. Meaning most mechanics are used to changing big components which wear or fail and that is all they focus on. The guys who worked on my car are great but they refuse to accept or just don’t understand that electronics play a huge part in the way the car works.

I cannot give you any advice other than to first ensure that all engine transmission and diff mounts are in good condition. Then look at all the suspension mounts. Then look to make sure the steel chassis cross brace you can see u der the engine is bolted really tight.. according to specs. This has been a source of clunks for some people.


I don’t think it’s your clutch. I chased down Santa Fe forums to see if anyone had issues with their clutch pack.. only one guy ever who spent a lot of time in soft sand. Meaning, that Bosch clutch pack is pretty bullet proof. Guys on this forum track their 997 turbos regularly and none have reported failures. It may be your diff.. and I believe they are rebuildable. In the USA, there’s bound to be some shop which can rebuild the front diff.

Good luck, let us know how you progress.

Ljt

Many thanks, Niels. I'll do what you suggested. I agree with you mechanics just like to replace parts, and hopefully fix the problem. Parts for our cars are not cheap. I will report back when the problem is fixed, hopefully and quickly.

Regards

LJT