If your TDI is not reaching full engine temperature and the air coming out of the vents is not very hot even on the hottest setting, it may be time to replace your thermostat. Luckily, replacing the thermostat on an ALH is a straightforward affair.
In this video Corey completes a fluid and filter service on an 01M 4-speed automatic transmission in a Mk4 Jetta TDI ALH. The 01M automatic transmission was first introduced in 1995, and was used on many VW models until 2006.
In this video Corey from IDParts.com replaces the alternator on a Mk4 Jetta TDI with the ALH engine. This will be the same procedure on a Mk4 Golf TDI and New Beetle TDI with ALH engines, though the New Beetle will have less room and may require more disassembly.
On the ALH engine the injection pump timing is measured using a scan-tool, like a VCDS tool. Procedure Turn on the vehicle and open VCDS Click on 01-Engine Click on 04-Basic Settings In the group field, enter “00” and “GO” button A new window with a graph will appear Select the Mk4 ALH Engine in ...