Join Date: Nov 2003
Location: Houston Texas USA
Change the timing belt
I want to reiterative what another poster said about changing the timing belt and (more importantly) the tensioner. You are way over due for a new belt.
The timing belt failure mode for these engines, is different than most toothed belt engines. The failures typically don't occur at high RPM or high loads.
They occur when the motor is first started in the morning, or other strange events like when the car is parked in gear, in a parking lot. Another car bumps your car slightly, and then takes off. You come back, turn the engine on, the belt skips and the valves collide.
What happened was that when the car was bumped; the motor was turned in the wrong direction, putting slack into the belt.
When you then started the car the belt was lose enough to jump.
There are lots (and lots) of threads on this board about V6 timing belts and tensioners. Here's the short version.
When your car was built it had what is called a "Hydraulic Tensioner". These worked very well but tended to leak oil.
Alfa then replaced the "Hydraulic Tensioner" with a new kind of tensioner called a "Mechancial Tensioner".
The mechancial tensioners did not have the oil leak issue but introduced the new problems mentioned above; not providing enough belt tension.
This led to a Mr. Tom Zat designing, developing and selling a third kind of tensioner called the "Zat Tensioner".
This was a simple all mechanical style tensioner, that replaced the Alfa mechanical tensioner, but maintained adequate belt tension at all all times. Unfortunately Mr. Zat no longer makes or sells them.
The timing belt tensioner is located under, and is hidden by the plastic timing belt covers. If you know what to look for you can figure what tensioner you have without removing the plastic timing belt covers.
Okay, figure out what tensioner you've got.
A. Original unmolested hydraulic tensioner - Very rare to find this, but if you do; open a bottle of Champagne, pass go, collect $200 and order a rebuild kit and a new bearing. Replace the belt, rebuild the tensioner, inspect the bearing and replace it if necessary.
B. Zat tensioner - Also rare, but the same result as "A"; open a bottle of Champagne, pass go, and collect $200. Inspect the bearing, and if it's okay, leave it alone and just replace the belt.
The bearing is currently available. It was unavailable for several years, so even if your bearing is good, buy a new one and stick it in your part's stash / horde (hoarding parts is an unfortunate necessity of Alfa ownership). The Zat tensioner uses the same bearing as the original hydraulic one.
C. Mechanical Tensioner - The most likely scenario. Do not pass go and do not collect $200. Instead call up the all Alfa junkyard, called "APE" (Alfa Parts Exchange) and see if they will sell you an original hydraulic tensioner. Fit this to your engine.
You'll need to modify it to run in the "dry" configuration, and you'll need the rebuild kit and a new bearing.
Alternatively you could just purchase another mechanical tensioner, install it, a new belt, and cross your fingers.
The "Mechanical Tensioner" has being the subject of much heated debate on this forum. Some people swear by the "Mechanical Tensioner" , most people (myself included) swear at them. I won't have them in my cars.
Well that's enough for now.