Questions and Answers

Jetta Thumping And Stalling Q. Hi, hoping you can help me. My question is: two days ago, my Volkswagen Jetta started making this loud rhythmic thumping or knocking sound. It sounds like it's coming from the front of the car, and it doesn't make the noise while idling or just revving the engine.

When I speed up, the sound gets faster, and same when I slow, the noise slows. The really weird part is it doesn't start thumping until after I have been driving for about 15 minutes. I took it to my mechanic but they said they test drove it, and got no such knocking sound (they obviously didn't drive it long enough) Please help!!!!!!!

Also, If I'm allowed to ask two questions. I also have a problem with my Volkswagen Jetta stalling out in stop and go driving. If the highway is bumper to bumper traffic for 15 minutes or more, my car will start to idle fast then slow to the point of almost stalling. It repeats this revving for a few moments then inevitably stall out completely.

Then the engine will turn, but it won't start. I have to let it sit for about 10 minutes, then it starts no problem. Please help me, as I really love my Volkswagen Jetta otherwise.

1987 Volkswagen Jetta
4 cylinder
Manual transmission
130,000 miles
Carburetted

George

A. Well, since the noise changes with vehicle speed and not engine speed, that puts it in the drive train. In this case the Constant Velocity (CV) joints or the front wheel bearings. What I would do is make arrangements with your mechanic for you to come by and take him for a ride when it makes the noise.

As for the stalling when hot, It sounds like an ignition module, But first we have to check for fuel and spark when it dies. When it dies pull a plug wire, stick an old spark plug in and lay it on something metal so it has a good ground. Crank the engine and see if there is spark. If not, then it's an ignition problem.