1998 OLDSMOBILE 98 Engine And Engine Coolingcooling System Problems

MY 1998 OLDSMOBILE REGENCY WAS LOSING COOLANT. I COULD NOT SEE A VISIBLE LEAK. THE CHECK ENGINE INDICATOR LIGHT CAME ON, SO I TOOK THE VEHICLE TO BE SERVICED. THE MECHANIC FOUND THE UPPER INTAKE (PLENUM) TO BE LEAKING THE COOLANT INTO THE ENGINE (CYLINDER #3.) THE LEAK WAS CAUSED DUE TO THE FACT THAT THE INTAKE PLENUM IS MADE OF PLASTIC. I INTEND TO SEND OLDSMOBILE A COPY OF MY BILL WHICH WAS $533.32. WHY WOULD A COMPANY MAKE A PART SUCH AS THIS OUT OF PLASTIC? BY THE WAY, MY INDICATOR LIGHT IS STILL ON, SO I WILL NEED TO HAVE A DEALER CHECK IT OUT, AS THE ORIGINAL MECHANIC CAN FIND NO REASON FOR IT REMAINING LIT. *NM

I OWN A 1998 OLDS REGENCY WITH 62000 MILES ON IT. THIS CAR HAS THE STANDARD 3.8 LITER V-6 WHICH HAS BEEN IN PRODUCTION FOR PROBABLY 30 YEARS. I NOTICED RECENTLY THE COOLANT RESERVOIR LEVEL WAS SLIGHTLY DOWN AND ADDED COOLANT TO BRING IT UP TO LEVEL. TWO WEEKS LATER MY ENGINE TEMPERATURE WAS SLIGHTLY HIGH SO I CHECKED THE RESERVOIR LEVEL AGAIN. THE RESERVOIR WAS DRY AND I COULDN'T SEE ANY COOLANT IN THE RADIATOR. I CALLED THE LOCAL DEALERSHIP, ADDED DISTILLED WATER AND GOT IT THERE. WHEN I ARRIVED THERE WAS COOLANT LEAKING OUT OF THE INTAKE MANIFOLD. THE DEALER INFORMED ME THE NEXT DAY THEY HAD TO REPLACE THE UPPER AND LOWER INTAKE MANIFOLDS AND GASKETS AT A COST OF $1050. I QUESTIONED MYSELF AND THE SERVICE MANAGER HOW AN INTAKE MANIFOLD COULD GO BAD. HE INFORMED THAT THE UPPER MANIFOLD WAS MADE OF PLASTIC. I TALKED...