TECH TIP FOR MARCH, 1994

IN A PREVIOUS TECH TIP WE ENCLOSED DIAGRAMS OF THE "CLOCKING" POSITIONS OF AN ALTERNATOR. UNFORTUNATELY WE DIDN'T TELL YOU THE EASY WAY TO CHANGE THEM (WITH OUT DISASSEMBLY &/OR DROPPING THE BRUSHES).

FIRST TAKE THE FAN AND PULLEY OFF, THEN STAND THE ALTERNATOR ON THE THREADED PORTION OF THE ROTOR AND TAKE OUT THE THRU BOLTS WHICH HOLD THE TWO HALVES TOGETHER. WITH ALTERNATOR STILL STANDING ON ITS ROTOR, TAP THE FRONT HOUSING DOWN THE ROTOR SHAFT UNTIL IT RESTS ON THE WORK BENCH.

WITH THE FRONT HOUSING ON THE BENCH, SWING IT AROUND UNTIL YOU ARRIVE AT THE DESIRED POSITION, THE PULL THE HOUSING UP THE ROTOR SHAFT UNTIL THE TWO HALVES ARE BACK TO©GETHER. REPLACE THE THRU BOLTS, & THE FAN AND PULLEY.

FROM THE FIRST TIME THAT YOU STAND THE ROTOR ON ITS THREADED PORTION UNTIL YOU HAVE REPLACED THE THRU BOLTS, THE ALTERNATOR REMAINS RESTING ON ITS THREADS ON THE BENCH. IF YOU LIFT IT UP THE ROTOR WILL PROBABLY FALL OUT, MEANING A WHOLE LOT MORE WORK.

FROM BLACK BROS. AUTO ELECTRIC IN  HAMILTON, COMES THIS NEXT PIECE OF ADVISE. ON MOST G.M. CARS USING THE 307CI (5.0L), "Y" ENGINE, THE WATER PUMP IS DRIVEN BY THE AIR/P/S PUMP, AND THE WATER PUMP IN TURN DRIVES THE ALTERNATOR. THIS LEADS TO THE CONDITION WHERE THE ALTERNATOR BELT IS TIGHT, BUT THE ALTERNATOR IS NOT FUNCTIONING PROPERLY BECAUSE IT'S NOT SPINNING FAST ENOUGH.

THE CULPRIT IS THE DRIVE BELT FROM THE AIR/P/S PUMP, WHICH IS WORN OR LOOSE AND IS NOT TURNING THE WATER PUMP FAST ENOUGH. IN WINTER YOU WILL NOTICE ONLY THAT THE ALTERNATOR ISN'T WORKING UP TO SNUFF, BUT IN THE SUMMER YOU WILL PROBABLY FIND THE CAR OVERHEATING AS WELL.

THE "SINGLE BELT" SYSTEM ON CARS & TRUCKS HAS CREATED A NEW SERVICE PROBLEM, WHICH CAN CAUSE YOU EMBARRASSMENT OR MAKE YOU EXTRA MONEY. MOST OF THESE SINGLE BELT SYSTEMS HAVE AN "AUTOMATIC TENSIONER" TO KEEP THE DRIVE BELT PROPERLY TIGHTENED. THE CURRENT RULE OF THUMB SEEMS TO BE "IF IT MOVES, IT'S OK!"

UNFORTUNATELY THIS IS NOT THE CASE. MULTI GROOVE BELTS MUST BE MUCH TIGHTER THAN THEIR V BELT COUNTERPARTS, AND IF THE TENSIONER DOESN'T MAINTAIN THIS PROPERLY, PREMATURE ALTERNATOR FAILURE IS INEVITABLE!

IF THE TENSIONER IS PARTIALLY SEIZED OR THE INTERNAL SPRING HAS WORN OR HAS SLIPPED OUT OF ADJUSTMENT, EVERY TIME THE ENGINE CHANGES RPM, A LOOP IS FORMED IN THE SLACK OF THE BELT, AND SINCE THE ALTERNATOR IS THE MOST FREE SPINNING PIECE DRIVEN BY THE BELT, EVERY TIME THE LOOP REACHES THE ALTERNATOR, THE ALTERNATOR EXPERIENCES A SPLIT SECOND CHANGE UP OR DOWN IN RPM'S FOLLOWED BY THE REVERSE CHANGE A SPLIT SECOND LATER.

IT'S A BIT LIKE PLAYING THE CHILD'S GAME "CRACK THE WHIP" WITH THE ALTERNATOR BEING AT THE CRACKING END, ALL THE TIME. THIS "CRACK THE WHIP" EFFECT IS REALLY HARD ON BEARINGS AND EVENTUALLY ON THE WHOLE UNIT, WITH BEARINGS EXPERIENCING PREMATURE FAILURE WHICH CAN LEAD TO THE WHOLE UNIT SEIZING UP SOLID.

OVER THE LAST COUPLE OF MONTHS WE HAVE HAD TO WORK ON 2 ALTERNATORS OFF CADILLACS WITH THE 4.3L ENGINE, WHICH ARRIVED IN THE SHOP COMPLETELY SEIZED. IN BOTH CASES THE CARS WERE ON THEIR WAY DOWN THE HIGHWAY WHEN IT HAPPENED AND THE ENGINES STALLED INSTANTLY. FORTUNATELY BOTH DRIVERS WERE ABLE TO GET THE CARS STOPPED SAFELY, BUT THEY WERE LEFT STRANDED, HAD TO BUY A NEW ALTERNATOR, A NEW BELT, PAY FOR INSTALLATION, AND PAY TO BE TOWED OFF THE HIGHWAY; AND IN BOTH CASES THE AUTOMATIC TENSIONERS WERE NOT FUNCTIONING PROPERLY.

WE ARE TRYING TO GET SPECS FOR THE TENSION REQUIRED, BUT HAVE NOT HAD A GREAT DEAL OF SUCCESS SO FAR. ONE THING IS FOR CERTAIN, IF YOU CAN MOVE THE TENSIONER WITHOUT THE USE OF A RATCHET OR WRENCH TO PRY WITH, IT IS TOO LOOSE, AND YOU ARE NOT DOING ANYONE A FAVOUR BY LEAVING IT THAT WAY.

ON THE SUBJECT OF MULTI GROOVE BELTS, GATES CANADA LTD., SAYS BECAUSE THESE BELTS MUST BE TIGHTER THAN V©GROOVE, THEY SHOULD BE CHANGED, AS A "REGULAR MAINTENANCE" ITEM EVERY 60,000 KM. FROM OUR OWN EXPERIENCE, WE WOULD POINT OUT AGAIN, THAT IT IS PERFECTLY POSSIBLE FOR MULTI GROOVE BELTS TO SLIP, AND NOT SQUEAL.

NOT CHANGING THE BELTS WHEN REQUIRED, DOESN'T DO YOUR CUSTOMER ANY FAVOUR, IT JUST SETS HIM UP FOR A BREAKDOWN IN THE FUTURE, AND IT TAKES MONEY OUT OF YOUR POCKET. IF THE CUSTOMER DIDN'T WANT HIS CAR SERVICED PROPERLY WHY DID HE BRING IT TO YOU?