Q –  When I start my 1990 Carrera up in the morning, it clatters like someone has poured marbles in a blender. It scares the heck out of me but the noise goes away after just a few seconds. It only happens when the car has been sitting for a long time. I am afraid that I will damage the engine. How serious is this?   Mike

That is an obnoxious noise isn’t it? And yes, you should be scared. Noises like that usually get worse not better if you ignore them.

The first thing is to catch that symptom “in the act”. Since it only happens for a few seconds, an overnight stay will be needed and it will take two people to find it, one with a stethoscope at the ready and the other turning the key. Listen to the left side of the engine, just behind the distributor.

Odds are that you have a leaking camshaft chain tensioner on the left chain box. There are two tensioners, right and left and thankfully, the left one can actually be seen and touched (unlike a lot of things on your car).  And the left one is the only one that I have found to fail.

The tensioners are supplied with oil pressure when the engine is running.   When you turn the car off, they are supposed to stay filled with oil. But the tensioner on the left bank is mounted upside down and sometimes the oil leaks down. When you first fire the engine up, it takes just those few precious (and disconcerting) seconds for the tensioner to “pump up”.

The part is reasonably priced and the labor isn’t bad either. It is a small price to pay to save your engine and your nerves. –MC