G60 Problems
GT G60 | History | Technical | G60 Variants
The G60 supercharger has quite a bad reputation as being unreliable, this is not wholly undeserved, as most of the problems usually end up destroying the complete supercharger, I will divide the problems into the following groups; belt, apex seal, bearing, oil seal
Belt
The small timing belt on the left hand side of the charger has a very important job, it connects the two shafts which allow the displacer to "spin" inside the charger casing with 0.1mm accuracy, if this belt fails (breaks) the main shaft will keep turning but the balancer shaft will not, causing the displacer to "hit" against the walls of the charger casing destroying both usually putting a small hole in the side of the outer casing. It would be unusual for a belt to fail on it's own, even on hi-mileage chargers, this is more commonly the result of the displacer "dragging" inside the charger, this is usually caused by one of the following;
Apex Seal
The Apex Seals' job is to seal the airflow between the displacer and the outer casings. These are very low wear items and tend only to fail if a poor quality air filter is used allowing dust into the charger which mixes with oil from the PC Valve forming an abrasive paste which quickly wear away not only the apex seals but also the "rubbing faces" of the casing and the displacer, if this is not caught in time eventually the displacer itself comes into contact with the casing damaging both and causing the charger to "drag" which puts undue strain on the belt. It is also possible for the worn apex seal to become loose inside the charger, again causing severe damage, but this is very uncommon. FYI the apex seals on the outlet side of the displacer wear quickest.
Bearings
There are five bearings in the charger, two sealed ones for the balance shaft, which I have never seen fail, and three bearings which run on the main shaft, one in each casing and a roller bearing in the displacer, all of which are lubricated by the engine oil. The original pulley case bearing has a plastic cage which under extreme circumstances can shatter causing it to lock-up, a bearing with a metal cage is used by certain rebuilding companies to eliminate this problem. The outlet casing bearing, also a roller bearing, seems to be reliable under all but the most arduous conditions. The high speed needle roller bearing in the displacer is the most highly stressed bearing in the charger and is rated at 13,000 rpms, the only uprated bearing that I am aware of is specially made for a rebuilding company and they will not sell them seperately.
Oil Seal
There are five oil seals in the charger, all of which are on the main shaft, the main two to worry about are in the displacer, when these leak the cause oil to pool inside the charger which then interferes with the close tolerances between the diplacer and casing causing drag, again putting pressure on the belt.
Preventitive Maintenance
There are two things that keep a G60 alive clean air and clean oil. I would also change the small belt every 50,000 miles and the send for a rebuild once you detect ANY loss of boost or visual oil leaks. An oil coating inside the tubes is normal and should only be considered a problem if larger quantities appear which are slightly different in colour and texture to that found on the tube walls.