TECH TIP FOR JULY, 1997

SOMETHING HAS COME UP A COUPLE OF TIMES IN THE PAST MONTH AND I THOUGHT THAT IT WOULD MAKE A GOOD START FOR THIS MONTH'S TECH TIP.

WE KEEP GETTING ALTERNATORS (USUALLY LATE GM OR FORD) WITH THE COMPLAINT THAT THEY ARE STILL WORKING BUT HAVE A LOT OF BEARING NOISE, BUT WHEN WE CHECK THE ALTERNATORS THEY HAVE BAD RECTIFIERS. IN MOST CASES, WITH PARTICULARLY THESE TWO ALTERNATORS, A SINGLE BLOWN DIODE WILL ALLOW THE ALTERNATOR TO CHARGE ENOUGH TO TURN THE  IDIOT LIGHT OUT, AND SHOW A VOLTAGE OUTPUT THAT IS ALMOST CORRECT (14.?) BUT THEY WILL HOWL AND NOT PUT OUT SUFFICIENT AMPERAGE TO MAINTAIN THE SYSTEM OVER THE LONG HAUL. ALTERNATORS CAN MAKE TWO NOISES, ONE IS A TRUE BEARING NOISE AND THE OTHER IS AN ELECTRICAL NOISE.

UNFORTUNATELY BOTH NOISES SOUND JUST ABOUT THE SAME WHEN UNDER THE HOOD OF A CAR, THE SIMPLEST WAY TO DETERMINE IF THE NOISE IS BEARING OR ELECTRICAL IS: THE SHUT THE CAR OFF AND DISCONNECT THE PLUG TO THE REGULATOR. RESTART THE CAR AND IF THE NOISE IS GONE THEN YOU HAVE AN ELECTRICAL NOISE, BUT IF IT'S STILL THERE YOU HAVE A BEARING NOISE. SINCE THE COST TO REPLACE THE MAIN RECTIFIER IS USUALLY MUCH HIGHER THAN BEARINGS THIS TEST WILL LET YOU FOREWARN THE CUSTOMER ABOUT THE POTENTIAL COSTS INVOLVED IN THE REPAIR.

ANOTHER THING THAT I SHOULD BRING UP, WITH THE ADVENT OF THE MULTI GROOVE SINGLE BELT SYSTEMS WE HAVE FOUND THAT NOT ONLY WILL THE BELT SLIP AND NOT SQUEAL, BUT IT ALSO TRANSFERS NOISE BETTER THAN THE OLDER SYSTEMS. IT'S ALMOST AS IF IT ACTED LIKE A GUITAR STRING AND TRANSFERS NOISE UP TO THE ALTERNATOR WHICH IS USUALLY THE MOST FREE SPINNING DEVISE AND THE ONE WHICH IS CLOSEST TO THE TOP. THIS MEANS THAT THE BAD BEARING IN THE WATER PUMP'S NOISE CAN BE EASILY TRANSFERRED TO THE ALTERNATOR. ONCE THE TENSION IS RELEASED FROM THE BELT IT IS SOMETIMES VERY DIFFICULT TO IDENTIFY WHAT CAUSED THE NOISE.

AT TIMES IN THE PAST I HAVE QUOTED AN "AMERICAN REBUILDER" WITHOUT NAMING HIM. THE GENTLEMAN IS MR. MOHAMMAD SAMMI, WHO WRITES ARTICLES FOR THE A.P.R.A. NEWS LETTER, THE "ELECTRICAL CONNECTION". THESE ARTICLES PROVIDE A GREAT DEAL OF THE INFORMATION THAT I PASS ON TO YOU.

IN A RECENT ARTICLE MR. SAMMI BROUGHT UP THE SUBJECT OF FORD STARTER RELAYS IN A WAY THAT NEVER OCCURRED TO ME BEFORE. IN THE OLDER POSITIVE ENGAGEMENT FORD STARTERS, THE RELAY WAS USED TO TRANSFER ALL THE POWER TO THE STARTER THAT IT USED, BUT ON THE PERMANENT MAGNET GEAR REDUCTION STYLE WHICH HAVE A SOLENOID MOUNTED ON THEM, IT TRANSFERS ONLY THE POWER REQUIRE BY THE SOLENOID.  THIS WOULD SEEM TO MAKE THEM LESS PRON TO FAILURE BECAUSE THEY ARE HANDLING LESS POWER, BUT ACTUALLY IT APPEARS THAT THE REVERSE IS TRUE. WHEN THE RELAY WAS HANDLING HEAVY POWER, THE CURRENT FLOW WOULD BE ENOUGH TO BURN OFF ANY OXIDATION BUT THE LIGHTER SOLENOID CURRENT CAN NOT DO THIS AND IN FACT MAY CAUSE THE EROSION OF THE CONTACT FASTER THAN IN THE OTHER APPLICATION. "CLICKING" PROBLEMS IN THE PMGR STARTERS MAY NOW BE CAUSED NOT ONLY BY THE STARTER, BUT BY THE SOLENOID, THE CORRODED WIRING AT THE SWITCH TERMINAL, BUT ALSO BY THE RELAY ITSELF. BECAUSE IT "LOOKS GOOD" DOESN'T MEAN THAT IT IS GOOD.

MR. SAMII IN THE SAME ISSUE ALSO POINTED OUT THAT SOME MANUFACTURERS HAVE GONE AWAY FROM THE FUSIBLE LINKS TO THE "JUMBO" ATO STYLE FUSES FOR SYSTEM PROTECTION. HE STATES THAT ON 1992 DODGE DAYTONA WITH A 3.0L ENGINE, CHRYSLER USED 2 OF 60AMP JUMBO ATO FUSES IN PARALLEL TO PROTECT THE CHARGING SYSTEM. IF ONE OF THESE FUSES WERE TO BLOW FOR ANY REASON THE SYSTEM WOULD CONTINUE TO FUNCTION UNTIL THE OUTPUT OF THE 90 AMP ALTERNATOR REACHED ABOVE 60 AMPS AT WHICH POINT THE SECOND FUSE WOULD BLOW AND THE SYSTEM WOULD SHUT DOWN BECAUSE THE ALTERNATOR WOULD NO LONGER BE HOOKED UP TO THE BATTERY. IT HAS BECOME CRITICALLY IMPORTANT THAT TECHNICIANS CHECK FOR AND CHECK THE CHARGING SYSTEM FUSES WHENEVER THEY GET NEAR A CAR, PROBABLY AS PART OF THE REGULAR MAINTENANCE THAT ALL YOUR CUSTOMERS DO .

LAST MONTH I TOLD YOU ABOUT THE "INTERNATIONAL AUTOMOTIVE TECHNICIANS NETWORK".  SINCE I JOINED I HAVE REVIEWED ABOUT 700 PROBLEMS AND ANSWERS AND IT HAS BECOME VERY CLEAR THAT THE ACQUISITION OF A LAB SCOPE IS BECOMING CRITICAL TO THE DIAGNOSIS OF MANY OF THE CURRENT AUTOMOTIVE SYSTEMS. FOR EXAMPLE, ON 89 & UP GM TRUCKS, AN OTC4000 "ENHANCED" CANNOT COMPLETELY SCAN THE O2 SENSORS, WHILE A LAB SCOPE CAN. THINK OF IT THIS WAY, IF WITH A LAB SCOPE YOU CAN SAVE WASTING HOURS OF TIME CHECKING OUT A SYSTEM, EACH HOUR SAVES YOU NOT ONLY THE SHOP/COST AND TECH/WAGES BUT ALSO THE LOSS OF REVENUE FOR WORK NOT DONE WHILE YOU WERE WASTING TIME FOOLING WITH THIS "UNSOLVABLE" PROBLEM. DOESN'T TAKE MUCH OF THIS TO MAKE THE SCOPE PAY FOR ITSELF AND BECOME A PROFIT CENTER.