Found here at
Buying a used mk1 TT
There are a few things one needs to look for when buying a mk1 TT. The most important thing is to check as to whether or not the timing belt has been serviced. The factory service interval is stated as being 100,000 miles, but it is well-known that the 1.8T’s timing setup is THE major weak point of the engine (specifically the hydraulic tensioner), and that it should be changed by about 60,000 miles; original plastic waterpumps also were known to fail. If you are looking into buying a TT with less than 60,000 miles get the belt setup serviced, otherwise its nice to get it done if higher in mileage and service records are unknown. The reason replacing the timing setup is so important is because the 1.8T is an interference engine and if the tensioner fails you can expect to need a rebuilt head or engine. It will cost about $300 DIY or $900 at a shop for a timing belt job, but in either case that is cheaper than a new engine.
Other small problems persist in mk1 TTs, though generally 2000-2002 are more finicky than the 2003-2006 model years. The glovebox latch is problematic, as they can get stuck because the mechanism fails, or the entire latch can simply pop off. The fixes are pretty easy (such as using a nail for a latch axle). The manual transmissions can have some grinding issues but they are almost always solved with new fluid and realignment of the shifter cables. The DSG has its own reputation, but the majority of issues come from early DSGs, and they can also be flashed to improve performance.
Another issue is rust on the two roof strips, but not the actual roof, which is part of the double-galvanized unibody; taking care of the rust only requires removal of the roof strips and a respray. Finally, other common problems are squeaky suspension bits or interior panels; if you hear a strange creak when you hit a bump, you probably need new bushings, and squeaky panels can be quieted with sound deadener.
► Various things to check when looking at a used TT coupe or roadster
- Driver seat left bolster for excessive wear
- Under the front and rear bumper for damage from curb stops
- Door sills for damage from people climbing in and out of car
- Speaker grills and bottom of door card for same damage
- Correct function of windows, lights, blinkers, hatch/gas release, locks
- Missing lines on gauge info display, correct gauge function, etc
- Correct function of the radio, all speakers and 6 disc changer
- Working glove box latch, functional softtop
- Complete toolkit and spare tire parts
- Solid hoses/connections in engine bay
- Condition of the battery in the spare well on a 3.2