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[Solved] 1989 Pontiac Firebird Formula 350 WS6 (5.7L V-8) eats alternators, why? How to fix ?


Topic starter

We are the original owners of a 1989 Pontiac Formula 350 5.7 L V-8 , tuned port injected, Firebird WS6 with about 150,000 miles. The front end of a Firebird in these years has no grill opening, rather an air dam on the bottom to direct air through the radiator. The car has gone through about 7 altnernators and we have no idea why they are failing. I suspect the althernators may fail due to high underhood temperatures?

The car is all stock and has a stock temperature thermostat. The temperature of the engine has always climbed in standstill traffic, I suspect becuase there is no grille opening. I cant recall if it did this when new.  The alternator failures have been fairly regular including somewhat early on in the car's life.  The car was a daily driver until about 1996 and has been garage kept since.

We do not use the car much since we have other cars and this makes the car unreliable. We would like to give it to our college age daughter to use as a dily driver, however, we dont trust the alternator situation. 

1) Why is the alternator failing (likely reason)?

2) How do we diagnose cause?

3) Is there a permanent fix to this issue? 

4) Is there a plug and play fix for this?

5) Any thought on overheating in traffic also welcome ( dual electric fans from factory, assume these need to be checked, they have been replaced once) ,

Saw a kit for an iceberg  in JC whitney with larger cooling fins for back of alternator years ago. Also looked at some expensive althernators which promised long life, and plug into facotry harness, but when delivered you had to cut the fatcory harness.

Thanks in advance , please help us make our baby reliable. If we missed any details please ask ,if you have any other advice feel free to offer. Thanks

4 Answers

Not going to burn out that fast on a car you're not using much from heat. More likely the electrical system has a problem corrosion somewhere battery terminals that are just so old they don't pass electricity right and they overheat from too much resistance then the alternator burns out I check all that first

Thank you. I'll check it out thank you. It probably wasnt corrosion when the car was newish. I'm also thinking of replacing the radiator with plastic tanks with an aluminum radiator. The plastic tanks can split and cause mass destruction.


Definitely an electrical problem. GM electronics become extremely frail as they age.

Thank you.


Change the battery

ok thanks ordered a new optima red top 75 series.

Topic starter

oh shoot, well too late, the new battery is on a truck on the way to my house as we type, Ill watch the video thanks. unfortunately I bought three batteries three years ago for three cars i seldomly use, i forgot to leave them on trickle charger.

The lead acid battery diehard silver in my 1990 caddy was shot and would not change after letting sit. even though it was only used a few times

The autocraft agm (Not spiral) battery in the 1989 firebird was shot and had 1.9 volsts and woudl only charge to 4 , it was 1 year old on shelf when they sold it to me. 

The Optima red top spiral agm in my 1967 firebid turned over the engine with no effort despite sitting with no trickle charger for 2+ years. I charged it and it si fine.

I find when i leave them all on troickle chargers then the gfci trips or something and the circuit in the wall quits working and the outlets are dead. This could also be becuase i added several flourexcent lights to the ciruit?  

What is a good battery to buy then? Or should i just keep them all on trickle chargers. Optima sells a charger which they says can recover deeply discharegd batteries. Are my batteries likely "deeply discharged" or do they have a bad cell. Is the expensive optima charger worth it? 

I have two battery tender brand chargers and on auotzone trickle charger. Should I leave these on the batteries full time?  i would guess so 



This post was modified 3 days ago by Sagewyn

Interstate, ACDelco, etc.

thank you