the guy tells me he has owned it for only 2 months with his mother giving it to him. he parked it right when the trans started acting up. so far as i know, the maintenance history is a mystery. I plan on asking him today if the timing belt has ever been replaced. Depending on his answer, I will make him an offer while taking the price of the transmission service and potential timing belt replacement into consideration.

in your guys opinion, what would this car be worth? 106k miles, interior and exterior are very well maintained.

but that is a GOOD running A6 4.2 without the pricetag of a timing belt AND transmission repair

As much as I would LOVE to have a 6-spd in this car, it would defeat the purpose of me buying it. Even with this transmission issue, its pushing it close. Im getting tired of having to fix cars or modify them to be better/faster/cooler. Ive done a 5.3/6spd s10, full built motor, s/c, 5spd 1992 Taurus SHO and a mid 10sec big block 1970 oldsmobile cutlass supreme. Its fun for a while, but then it just becomes a chore :/

And, FWIW, my guess too...
 

Own a 2000 4.2. Lost the tranny summer 2010 at around 110K. Sounds a lot like the description the OP gave of my issue--sudden bang and missed a shift on acceleration when it happened. Then after that consistent slipping in first and I had to baby it to avoid the SAFE mode and get it into the higher gears which still worked fine. Also found out then that ZF made running changes to the tranny innards in late 2000, among other things, to strengthen the same basket. Thanks ZF for learning that via customer breakdowns.

ZF factory rebuilt tranny installed and out the door, with all the later rev. internal improvements, fluids tax and all, was slightly over $4K.

^ This.

OP: Just so we're plain, these photos are likely what the inside of that transmission looks like now:

Clutch Drum A:
http://media.corrado-club.ca/albums/...drum_a_001.jpg

Clutch Hub B:
http://media.corrado-club.ca/albums/..._hub_b_002.jpg

Ask me how I got those photos :( If there are no maintenance records for the car and the tranny is acting up I would expect to budget an immediate $4000 for the tranny and $1500 for the timing belt. If you're smart you'll spend the additional couple hundred to replace the valve cover gaskets and cam seals while you're in there. I'd also set aside another $1500 - $2000 to replace the front control arms at some point in the near future, even if there's no clunking from the front end at the moment.

At 106K miles you're coming into the period where all the major maintenance items need to be addressed. Basically without the presence of records proving they've been done already you can expect to spend your purchase price again on maintenance for any A6 in good condition. In the case of the 4.2L you're looking at you have to add the cost of either a tranny rebuild or tranny swap on top of that. A6's were aimed at the executive market and while depreciation may have dropped their resale values like a stone, the maintenance costs haven't changed... they are expensive vehicles to maintain, especially if you have problems that need addressing like the tranny in your case.

My suggestion is, given that it's effectively dead in the water and needing an expensive transmission job, to either try and pick up this car with a really lowball offer (ie. $1500 - $2000) with the intent of using it as a project to swap a 6MT into or to walk away and look for a better maintained example if you still want to buy a 4.2L C5. The 6MT makes this a completely different car that's much more fun to drive, feels much more powerful as you're always in power band and has all of the transmission reliability issues removed. It's absolutely the route I'd go if my transmission every acts up again. However given the lack of maintenance records you may also be opening yourself up to a vehicle that will nickel and dime you to death with regular maintenance that's been missed or ignored.

this was really helpful. What would be the overall average cost of a 6spd swap?

I would RUN away from this car...especially given your comments on defeating the purpose of buying this car.

There are just too many good 4.2 A6's out there to fool around with one with a known transmission problem.

It's a parts car unless the guy wants to repair the transmission first and then you consider whether to buy it for $4-6K.

PS...that being said, I just put $6K into a new transmission on the S6....the car might be worth $12-14K to the right buyer but it was worth essentially nada with a bad transmission.

just pulled the code from the car. I got a P0730 Incorrect gear ratio. I read up on it and it ranges from people saying that it is low fluid, wrong fluid, bad tranny. Something new that I noticed was that when you put it into any gear, the in dash gear selector does not highlight anything. This guys bottom dollar is $2k

If the car is clean and he can document that the timing belt was done, I'd seriously considering buying the car. Find a good shop and price out a rebuild by a ZF certified rebuilder. If you can get the trans done for around $4k, you are basically buying the car for $6k with a new trans, a fantastic deal.

That means the transmission is in safe mode, P0730 Incorrect gear ratio simply means the TCM can't figure out what gear the transmission is in based on it's slip and speed. It's a pretty common code, but based on what you described above I stand by my statement that parts of that tranny look like the one's in my pictures.