5 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHC4S front diff
Leading reported evidence
Replace seals so it doesn't leak
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Discussions that contain suggestions
1
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Suggestion · Original poster
At a minimum i plan to change the seals so it doesn't leak.
Leading evidence: 'Replace seals so it doesn't leak' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace seals so it doesn't leak' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion · Original poster
I have a 2003 C4S with 35k miles and am changing the transmission and front diff oil.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion
They can be rebuilt for about $1100 and used ones should be 1/3 that cost.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
5 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261027T171335Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I have a 2003 C4S with 35k miles and am changing the transmission and front diff oil. The transmission oil looked good and didn't any issues. When i removed the panel under the front diff i noticed some greasiness around the diff but haven't had any drip in my carport. I drained the oil and it definitely wasn't as clear as the transmission oil. The drain plug also has quite a bit to metal around the magnet. At a minimum i plan to change the seals so it doesn't leak. Do i also need to have the diff rebuilt? It isn't making any noise yet.
I�d drain that oil down then put some fresh stuff in and see how it behaves. It�s easy to change out if it comes to that, but probably not necessary at the moment. In fact I�m sure a few folks will chime in and say just take the front diff out and leave it that way... It�s SOOOOOOO much better that way...
My front diff began leaking and making a very noticeable whining sound when off the throttle before I bought a low mileage used one from a RL 996 turbo owner who had removed it to go RWD. You will know when its time for replacement. They can be rebuilt for about $1100 and used ones should be 1/3 that cost. New ones are just stupid expensive and not a realistic option. Best of luck.
That metal residue on the drain plug doesn't look bad for 35k miles, especially if it's the original fluid in there. Change it and you'll be fine. Changing the axle seals is a good idea though since they're pretty inexpensive and easy to do.
Thank you for the feedback. I still am not sure if the differential is leaking. Although it was pretty greasy under there i drained right at 1.5 liters out of there so am just refilling it for now and will keep an eye under there. I did notice one of the boots on the CV joint was split so have ordered inner and outer boot kits and will replace this weekend.
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