Jim Grant's Tech Tips
'97 Volkswagen Jetta TDI, Hard Starting
Q: I own a 97 Volkswagen Jetta TDI. I had engine failure at 80k miles (internal oil line failure) so the engine was replaced by Volkswagen under warranty. Since then, it has a hard starting problem. If it sits over night it takes about 20 seconds of cranking before it will start (in a cloud of white smoke) Otherwise it starts and runs fine. The dealer says there is nothing wrong. Any suggestions?
- Regis C.
A: Volkswagen has their act together when it comes to getting their TDIs to fire up in cold weather. This past winter here in New England (thank you its over) was stupid cold. VWs diesels had no problem starting and running unless there was a problem. The problem youre describing only occurs after the vehicle has set and the engine is cold. A couple systems come to mind under those conditions that might explain your problem. The glow plug system is the main component for lighting the fire in a cold diesel engine. If the glow plugs are not heating up correctly it will cause extended cranking time. Usually VWs computer will alert you to a problem with the glow plug system, but you should never put total faith in computers. The second system I would suggest inspecting is the injection system. The newer diesel engines are a hybrid, a mix of mechanical and electronics for the injection system. But, they can still suffer from old school problems. You may have a leak in the system that is allowing the fuel out and air to get into the system. If air enters, the cranking time is extended while the injection system purges the air. A small system leak will be most pronounced after the vehicle has set an extended period of time. The problem with either of these systems, is once the engine has been started the problems gone until the vehicle sets. So if youre dropping your vehicle off in the morning at the dealership, it is very unlikely the problem will present itself. Plan to leave the vehicle overnight and be there in the morning to demonstrate the problem to the technician. Just realize that after you start the engine the first time the problem is gone. The technician will have an idea of what your problem is, but diagnosis may require installing equipment and waiting until the engine has cooled enough for testing/diagnosis. The actual time needed to diagnose and repair will be short compared to the time needed to allow for the condition/problem to occur.