| Own an Alfa for any length of time and you'll find that there are a few experiences you'll always have in common with other Alfa owners. Some are pleasant, like the wide-eyed stares as you motor past a crowd of people. Others, like unexpected mechanical problems, are not. What might surprise you is that many of those mechanical problems have their roots in seemingly unrelated areas. A perfect example of this is the relationship between your Alfa's engine and transmission mounts and other components.  Unlike many other aspects of the Alfa Romeo Spider design, the arrangement of the engine and transmission mounts is not unique to the marque. The triangulation of two engine mounts roughly midway down either side of the block, with a single transmission mount aft of the gearbox, is commonplace on longitudinal drivetrains. With Alfas, problems arise when these mounts begin to fail. Neglected mounts can lead to expensive and time-consuming repairs.
The job of any mount is, of course, to stabilize the engine and transmission in the appropriate position and also to isolate the inherent vibration from the rest of the chassis. The mounts support a great deal of weight, while also being subjected to torque, heat and in many cases, stray gas and oil. These factors cause the rubber to degrade rapidly. As it softens, the position and stability of the engine-transmission unit is compromised. One of the most common indicators of failing engine mounts is the "explosion" of the engine cooling fan blade and shroud. When the mounts are soft, the engine not only sits lower than intended, but also rocks from side to side as throttle is applied or retracted. The fan is mounted to the water pump at the front of the engine, while the shroud is mounted to the radiator on the chassis. If the engine drops low enough or rocks wildly enough, the blades contact the shroud and both shatter on impact. Worse yet, the resulting debris can punch holes in the radiator core and ruin it as well. Eventually, the path of destruction could result in the coolant escaping, the engine overheating and the head gasket failing, but usually the fan failure is dramatic enough to get the driver's attention fairly quickly. Electronically-injected Spiders are subject to a somewhat less dramatic problem, the repeated separation of the airflow meter hose from the plenum or the meter itself. As a poorly supported engine rocks, the hose gets over-extended and pulls away from the plenum or the meter, which causes the engine to stop running. A similar strain is applied to the radiator hoses, though it is generally not enough to cause a failure. The exhaust system also can fall victim to bad mounts, since it is attached to the engine, the transmission and the chassis and isn't isolated from engine vibration at all. The exhaust system, which is nearly as long as the chassis itself, can exert a tremendous amount of leverage on the manifold, hangers and its own components when its position varies from what Alfa's engineers intended. A cracked exhaust manifold and the premature failure of exhaust pipe hangers can often be attributed in part to bad mounts. It's also not unusual to have contact between the floor pan and the exhaust when the engine rocks as torque builds. At the aft point of the triangulation, the weakening of the transmission mount allows the gearbox to drop in the rear, raising the front of the engine while binding the drive shaft. This stress can lead to the failure of the rubber flex disc that joins the driveshaft and transmission, as well as the failure of the support and bearing between to two halves of the shaft. This usually manifests itself as vibration or a loud thumping noise from underneath the car. This contributes to excessive U-joint wear, which, if left unchecked, can ultimately ruin the rear half of the driveshaft.  It's also worth noting that a loosely supported engine can cause troublesome throttle variation, particularly on cable-actuated linkages. The engine’s movement can tighten or slacken the linkage, allowing the throttle to open or close independently of the driver's input. That’s not likely to cause failures or expensive repairs, but it will detract from your driving enjoyment.
The next time you schedule some quality time with your Alfa, you might want to give the mounts a close inspection. Finding a problem early might save you from a big headache (and a bigger repair bill) later. The less time your car spends in the shop, the more it spends on the road. And that, after all, is where it belongs. |
