TECH TIPS FOR NOVEMBER, 1998

FIRST, IT HAS BEEN A LONG SUMMER OF SATURDAYS OFF. BUT, NOW LIKE ALL GOOD THINGS, IT MUST END. WE ARE BACK ON WINTER HOURS INCLUDING SATURDAYS FROM 8:00am TO 1:00pm. THANKS TO MY CUSTOMERS FOR THEIR PATIENCE DURING THE SUMMER, THE SATURDAYS WERE A NICE VACATION.

SEVERAL MONTHS AGO I WROTE ABOUT THE NEED TO CAREFULLY CHECK THE AUTOMATIC TENSIONERS ON THE NEW CARS. THIS IS REALLY IMPORTANT WITH THE GM CARS BECAUSE IF YOU DON'T THE BEARING BEHIND THE FAN WILL FAIL AND THE ALTERNATOR WILL BE JUNK. ON ALL CADILLACS WITH THE 4.1L ENGINE THIS IS OF PARTICULAR IMPORTANCE, I THINK THAT THE BEARING IS TOO SMALL FOR THE BELT LOAD IN THE FIRST PLACE, BECAUSE MOST OF THE TIME WHEN WE TAKE ONE APART THE ROTOR SHAFT HAS BEEN DAMAGED BY THE BEARING.

THE FINAL WORD ON THIS IS, JUST BECAUSE IT MOVES, DOESN'T MEAN THAT IT IS CORRECT. I KNOW THAT THE TENSIONERS AREN'T CHEAP BUT NEITHER IS ANOTHER ALTERNATOR, NOT TO MENTION HOW IMPRESSED THE CUSTOMER WILL BE.

AS A FINAL KICK AT THE CAT, ON THE iatn, A TECHNICIAN REPORTS HAVING A CUSTOMER COMPLAIN ABOUT A HUMMING NOISE ON THEIR 1994 ACCORD. A FAIR BIT OF TIME WAS SPENT ELIMINATING ALL THE NORMAL THINGS INCLUDING THE ALTERNATOR, IT WAS NOTICED THAT THERE APPEARED TO BE AN ACCUMULATION OF BELT MATERIAL ON THE FRONT OF THE ALTERNATOR. THE CUSTOMER TOLD HIM THAT THERE HAD BEEN A TIMING BELT FAILURE AND THE PROBLEM SEEMED TO START AFTER THAT WAS FIXED. IT TURNED OUT THAT THE TENSIONER WAS NOT RELEASING CORRECTLY AND A NEW TENSIONER FIXED THE NOISE PROBLEM. IT ALSO FIXED AN UP-COMING ALTERNATOR FAILURE!

ANOTHER TECH REPORTED A 1990 CHEV G-20 W/5.7L, WHERE THE ALTERNATOR FAILED 3 TIMES IN 4 MONTHS. ALL SYSTEMS WERE CHECKED WITH NO APPARENT VOLTAGE DROPS AND IT WAS FINALLY FOUND THAT THE WIRING HARNESS HAD RUBBED THROUGH WHERE IT CROSSED THE TOP OF THE A/C. IT SEEMS THAT UNDER THE CORRECT CONDITIONS IT WOULD SHORT OUT AND CAUSE THE ALTERNATOR TO FAIL.

SOME OF THE OLDER VEHICLES CAN PRESENT PROBLEMS BECAUSE WE DON'T WORK ON THEM AS FREQUENTLY AND HAVE FORGOTTEN THE LESSONS OF THE PAST. A 1968 PONTIAC FIREBIRD W/350cid EXHIBITS A VOLTAGE VARIATION OS 14.0 TO 15.5 AT IDLE OR AT SPEED, WITH OR WITHOUT LOAD. A NEW BATTERY, ALTERNATOR AND REGULATOR FAILED TO SOLVE THE PROBLEM. IT WAS FINALLY TRACED TO A POOR GROUND CONNECTION.

MOHAMMAD SAMMI, WHO I MENTIONED IN LAST MONTHS TIPS, HAS RE VISITED A PROBLEM THAT SOME OF THE FORD CARS AND TRUCK HAVE. FORD NOW USES A PMGR (PERMEANT MAGNET GEAR REDUCTION) STYLE STARTER WHICH HAS A SOLENOID MOUNTED ON IT, JUST LIKE A REAL STARTER SHOULD. THIS STARTER HAS BEEN A PROBLEM BECAUSE OF CORROSION AT THE TERMINAL WHERE THE SWITCH WIRE CONNECTS TO THE SOLENOID AND FORD HAS ADDRESSED THIS.

NOW THERE APPEARS TO BE ANOTHER CAUSE OF " CLICKS BUT WON'T START. WHEN THE CHANGE WAS MADE TO THE PMGR STARTER, FORD RETAINED ITS FENDER MOUNTED START RELAY (WHAT WE USED TO CALL A SOLENOID), ONLY NOW THEY USE IT AS A MAG SWITCH TO ACTIVATE THE SOLENOID MOUNTED ON THE STARTER. THE PROBLEM APPEARS TO BE THAT WHEN THE RELAY WAS USED TO SUPPLY POWER TO THE STARTER, THERE WAS ENOUGH CURRENT FLOW TO BURN OFF ANY ARC CONTAMINATION. WITH THE RELAY NOW ONLY CONTROLLING THE SOLENOID, THERE IS NOT THAT CURRENT FLOW AND THE RELAY MAY NOT ALWAYS MAKE PROPER CONTACT. THIS LEADS TO A "CLICKS BUT WON'T START" OR AN INTERMITTENT "WON'T DO ANYTHING"

THESE RELAYS ARE MOSTLY ON THE FIRST YEARS OF THE PMGR'S BUT YOU SHOULD CHECK ON ALL FORDS, 1991 ON, FOR THE PRESENCES OF ONE. IF ONE IS PRESENT, AND YOU ARE CHANGING THE STARTER, CHANGE THE RELAY. I DON'T CARE IF IT "LOOKS GOOD" YOU CAN'T SEE INSIDE, SO CHANGE IT!