2.8L V-6. I had a S-10 Blazer with that engine. The noisiest, most underpowered piece of crap ever conceived. It lasted 50k. That's when I traded it in for a '93 Jeep GCherokee. (By the way that was the last new GM product I will ever buy). The 4.0L Jeep engine by comparison is probably the best six cylinder ever made modern times.

 

301 Turbo that was used in 1980/1981 Trans Am.

 

The absolute worst GM engine EVER - the 350 gasoline engine converted to diesel.
Bar none. Baaaaaaaaaaaaaddddd.

Second worst - 1st generation Vega aluminum 4 banger. You didn't change the oil every 3,000 miles. You replaced the block.
The Cosworth engine was pretty good for making power.

Wasn't there problems with the earlier Wankel (sp?) engines, too? Seals, I think. Maybe rotor seals.

 

I see no one mentioned the short-lived Cadillac 4-6-8 engine, a good idea that was too far ahead of available technology.
Dono

 

I had a Vega with the 2300 cc, the car burnt alot of oil at 40,000 miles.

I had a budy at a machine shop pot crome moly sleves in the block and shave the head. I built a set of split headers and put on 500 cfm holly 4bbl. This was before tunner cars and 4 bangers but when I was done I could run 17 second 1/4 miles on street tires and this little 4-bangerr was un-stopable stop light to stop light

 

I had a Vega with the 2300 cc, the car burnt alot of oil at 40,000 miles.

I had a budy at a machine shop pot crome moly sleves in the block and shave the head. I built a set of split headers and put on 500 cfm holly 4bbl. This was before tunner cars and 4 bangers but when I was done I could run 17 second 1/4 miles on street tires and this little 4-bangerr was un-stopable stop light to stop light

 

I own one presently. It's in a 91 Olds Cutlass Calais. You're right, they're not much for power (110 rated) and they're VERY noisy. The timing chains have issues. They are pretty cheaply built, too. VERY thin head decks, thin head castings (no porting), weak crankshafts (5200 RPM max and 150 HP max), and heavy.

I can [could] easily reach 90 MPH with mine. It consistently gets 30 MPG with the 125C (3T40) transmission, and all on 3.5 cylinders. I say "could" because I have to remove it this weekend and rebuild. It finally pooped the bed. It still runs, but I think I have a broken piston. It's got 160K on it and I think more crankcase vapors come through the breather than exhaust out the tailpipe. My air filter lasts about 2K miles before it's completely soaked.


I'll get it put back together and see what she does. She was a neglected, worn out pile when I got her for free anyways.


Bad GM engine? 2.8/3.1/3.4/new 3.5


Cody

 

I had the Olds 350 diesel in an 80 chevy half ton. As a prior owner I cant testify to what a POS it was.
Another bad idea was when they put the integrated intake manifold/cylinder head on the 250 straight six. They took a great motor and ruined it. I haven't seen one yet that the head didn't crack on, the one I had included.

 

i dunno my cavalier has 114,000 miles and 3 engines.

runs like a raped ape but doesn't last long...

well mostly because i run it like a raped ape too.

 

I've forgotten all about the Cadillac 4-6-8 engines, those were horrible engines.

 

I personally would have to agree with many on here that the 2.3 vega engine would have to be the worst, some mentioned the 350 diesel but it atleast had some redeaming qualities, basically forged steel crank, very good rods, and 4 bolt main block so you could take the heads off, change the pistons, and build a respectable race engine out of the bottom end. As far as I could ever tell the vega engine only had one redeeming quality it was light so not hard to throw away, and bieng alum you could actually get some scrap value out of it.

 

That was an actual Chevy motor, a cross between a 283 and 327. It was a 327 crank in a 283 block.

 

i personaly despise the olds 307, less power than your average v6, same milage as your average 350. some people say their super tough, i dont belive that, im on my second and its blowin blue smoke with only 100 000 kms. and they all came with the feedback quadrajet that never worked right. the quad 4, the 350 diesel, and the vega 4 cyl are crap piles but thats a given

 

i personaly despise the olds 307, less power than your average v6, same milage as your average 350. some people say their super tough, i dont belive that, im on my second and its blowin blue smoke with only 100 000 kms. and they all came with the feedback quadrajet that never worked right. the quad 4, the 350 diesel, and the vega 4 cyl are crap piles but thats a given

 

I'm hearing a lot of negative on the olds 307. We had one in a 1982 Delta 88.. Mated to a 2004R trans. This thing would eat supercharged bonenvilles light to light.. I know I was there when the little brother did it... The thing pinged like hell all the time (base timing was 25 degrees or thereabouts), and got ~28mpg on the road... This was all with 183k miles on it.. Little brother totalled the car at ~190k, but it still ran good. The Chevy 305 gets my vote for worst, it was a weak engine. The 350 diesel was a good engine as long as you didn't drive it in town much.