,
From 1999.5 until 2005, VW offered the TDI engine in the MKIV Jetta and Golf, with the Jetta coming as a sedan or wagon. These models will be the easiest used TDI to find in North America and are more comfortable than the previous generation TDIs. From 1999.5 through 2003, the MKIV models featured the code ALH engine, which produced 90HP and introduced a Variable Nozzle Turbine (VNT) turbo among other changes. Problem areas include vacuum lines causing limp mode (no hose in the ECU anymore, however), clogged intake manifolds, and sticking VNT vanes.
2004 introduced the “Pumpe Duse” (PD) engines making 100HP. The newer PD engines did not suffer from vacuum line failures and clogged intakes as often, but can be subject to accelerated cam wear due to poor oiling of the camshaft, so it may be worth your time to pull the valve cover to inspect. Any PD TDI serviced at a monkey lube or where the owner cannot verify the use of a VW 501.01 equivalent oil, should be treated with extreme caution.
All MKIV models suffered from Dual Mass Flywheel (DMF) issues, and if the car exhibits excessive vibration at idle, but the tach shows a stable idle, expect to replace the clutch and flywheel immediately. The four speed automatic offered through 2003 is generally considered garbage as it is not only unreliable, but also not rebuildable. However, the 5 speed automatic offered in later models is considered reliable. If equipped, check the sunroof drains to ensure they work properly, as interior flooding can result from clogged drains. Timing belt replacement intervals started at 80,000 miles, but a long-life 100,000 kit was later offered, and the automatic versions originally came with 60,000 mile timing belts due to their larger 11mm injection pump. The ALH MKIV Jettas and Golfs generally attain the highest fuel economy numbers of the TDI family – between 40 and 50mpg – due to better aerodynamics, VNT turbo, simpler fuel system, and lack of Diesel Particulate Filters (DPFs) found on newer models. Expect to pay between $1500 and $10,000 for MKIV models, with four door Golfs and Jetta Wagons priced noticeably higher.
 |
| The MKIV TDIs were offered in two and four door hatchbacks as the Golf, and Jetta Sedans and Wagons (pictured above). Four door Golfs and Jetta Wagons with a manual transmission are less common than their Jetta Sedan platform mates, making competition to purchase one generally stiff. Expect prices to match or long lines of buyers for clean examples. Photo courtesy of Chris Lane. |
 |
| Pierre Bigras’ clean MKIV Golf TDI that is no stranger to the track. Photo courtesy of Pierre Bigras. |
From 2006-2006.5, VW switched to the MKV chassis for the TDI Jetta. These models offered 100HP engines very similar to the PD MKIV Jettas, as well as an optional DSG 6 speed automatic. All MKV TDIs suffered from possible accelerated cam wear, so verify the use of a proper 501.01 oil, and also suffered from DMF issues. Timing belt intervals for these cars are 100,000 miles, and the DSG fluid can cost as much as $900 to replace if you pay someone, or $150 or so if you do it yourself, so keep that in mind when deciding between a manual transmission and the DSG unit. MKV chassis cars generally return 38-45mpg.
