One of the biggest problems with 60-degree engines not running properly tends to be the engine grounds getting dirty and losing proper contact.  

While tracking down a problem with my 1990 Grand Prix STE (3.1 MPFI, and 440T4), I decided to go ahead and clean the 2 engine grounds.  The procedure for cleaning these 2 grounds is very similar to cleaning them on the 3100 SFI, and the 3.4 DOHC as well.

Of the 6 engine to transmission bellhousing bolts, the front 2 (directly over the starter) are used as the grounds.  Over time, grime, oil, transmission fluid and other nasty stuff builds up on them and can lead to problems.

Here is what they looked like on my 1990 Grand Prix STE before I cleaned them.  This is only the top one of the two, but as you can see, it is REALLY dirty, and the bottom one was worse.

To do this, I chose to remove some things to make access easier.  I removed the BATTERY CABLES, AIR CLEANER, DRIVERS SIDE TORQUE STRUT (DOGBONE) DRIVERS SIDE COOLING FAN, EXHAUST CROSSOVER, and THROTTLE DETENT CABLE (440T4, and early 4T60 only).  This gave me room to not only do the work, but to see what I was doing.

This is the ground with everything removed.  As you can see it is REALLY nasty under there.





I used a combination of ENGINE DEGREASER and CARB CLEANER to get the dirt off.  I sprayed on the degreaser, and would wait a few minutes, then spray more.  Once that can was empty, I used the carb cleaner to get the degreasers thick residue off.  In the end, I had some really clean mounting points.  I also used the carb cleaner to clean the ends of the wires.

Here are the clean mounting points.

I then reattached the wires to the clean points.

After everything was reattached, I reinstalled everything and tested it out.  Some of the minor issues that I had were fixed after cleaning them.