GM's best engine: 3.4 or 3.8 ?

I was quoted once with GM's engine that was (one of it's) most reliable, best choice overall ( considering reliability, power, gas mileage, etc) I can't recall if it was the 3.4 or 3.8 engine, (or maybe even the 3.1)

If i was to guess it would be a 3300 or a 3800

pat...

Why would you recommend the Caddy 472, when the Caddy 500 produced more power, and had better cyl. heads?

Quid quid latine dictum sit altum videtur.
(That which is said in Latin sounds profound.)

Gee , I would have thought it would be the Cadillac 4100 or the Vega 4 cyl.

Of the three you mention, the 3.8 is the *only* one by a *VERY* large margin that qualifies as one of GM's better efforts. The 3.1 and 3.4 are garbage.

I could never understand why these 2.2s and 2.5s have so much more pin noise than other similarly designed engines. Anyone have an answer ?

Must be a pre 1999 car.

The 3.1L engine from 1999 onward are prone to a problem known as piston slap. Mine only lasted 46,000 kms before GM had to put a new engine in my car.

If you are sticking with V6s, surely you can't go wrong with the 4.3?

Lol... no. He means why is the 3.1 and 3.4 junk?

My 13 year old 3.1 has over 200k miles and it still leaves black marks when you want to.

"Daniel J. Stern" wrote

Well, that one is coming back in the trucks.
But, I'm sure that GM's implementation of the system will be much better this time around.

Rough idle, increased oil consumption, less power, sounds really noisy at start up.

In my case, the pistons were still "slapping" 5 minutes after the engine was started.
Dunno. With mine, the slapping gouged two of the cylinder walls.

"Victor Smith" wrote

It's hard to think of one GM vee engine that doesn't eventually leak oil or coolant from the intake gasket.

1995 seems to be the year that the problem started with the VIN K 3800. One option would be to buy a supercharged
3800. Even in the GenII format, the supercharged version doesn't use the plastic intake.

Are you sure its piston slap? Chrysler 2.2 and 2.5 engines are known for a lot of wrist-pin noise (also harmless), but less so for piston slap.

Approximately 8/23/03 06:23, PAROADHOG uttered for posterity:

My bet is the old stove bolt inline 6.

yeppers...1994 Pontiac Grand Am.

I had the same information, quoted on rec.autos.tech some time ago, which said the 3.4 was the best ever.

All the V6's, from 2.8, 3.1, 3.4, 3.4DOHC, and 3.8 have some drawbacks.
I think that most of the problems can be solved or avoided if you are going to rebuild.

The 3.8 or 3800 is pretty good however. I have no information higher CID
V6's.

Ok, Ian. I've never had problems with 2.8's (mfi) or 3.1's I've purchased for me and my kids (but I better talk to my son who's running a 3.1 and recently told me he's losing coolant).
I'm chalking it up to luck.
You got me scared now, because I'm about to pick out a used
LeSabre for my road car. A 3.8, natch.
What year models *don't* suffer chronic intake leaks?

HAH! Well.... there too.

But really, she's still as strong as the day I got 'er. A bit more loose in the suspension and feel for the "Pontiac performance", but she'll go like mad (trashed motor mounts and all)

"JazzMan" wrote

The Fiero's v-6 was a bit different from the average
2.8 engine. I think the only other car that got that style of 2.8 with upper and lower plenums were the Pontiac
6000 STE's.

But they did leak coolant into the engines occasionally.
I worked on Fiero's non-stop from the time of their inception to the early 90's. It was not as common of a repair on the Fiero's, but then there weren't as many of those engines running around as the base throttle body injected 2.8's.

No matter, they had enough other screwups on the
Fiero to make up for not many intake gaskets leaking.

I have a neighbor with a 3.1 and there is 297,000 miles on the motor.
FACTORY MOTOR, NOT REBUILT. It runs like a champ. It leaks oil out of the valve covers, but no noises or anything. And these are true hihway miles.
and hour and a half drive to and from work every day for 2 years.
Anything will last if you keep up with the oil changes and other routine maintenance.

Ooh! No! The Oldsmobile Dieselized 350...NO! WAIT! The Cattle-hack
V8-6-4-0!

They made a best engine?

My pick:
The 283 V-8.

I've been reading about all of the problems with the GM 60° V6 engines, but I'm confused. I'm a fan of Fieros, particularly those with the
2.8L V6. The newest of these cars is now 15 years old, and examples of these with mileage under 100k miles are fairly rare. Mine currently has 154k miles on the chassis and 33k miles on the engine. As a member of a forum with over 7k members I feel like I'm fairly attuned to the
Fiero community at large, so I see first hand what kinds of problems the 2.8 engines tend to have. Rod bearing failures are common in high mileage engines, particularly ones with a history of poor maintenance or abuse. Ignition modules blow left and right, distributor pickup coils and ignition coils are right behind. Cam lobes wear down, but remember, these engines are pre-roller lifter designs, so that's to be expected to some extent.

But the one thing that doesn't happen, and I have never in all my experience seen happen to either myself or any one of the other Fiero owners that I'm aware of, is intake gasket failure leading to coolant in the oil. I've seen blown head gaskets (rare) that result in coolant consumption, I've seen leaky water pumps, but never even one intake gasket failure. Why is that? I know many people who have installed the 3.4 block and heads into a Fiero, utilizing the Fiero's intake manifold and gaskets. They don't have any history of leaking, and this is a swap that's been going on for at least 7 years that I know of.

What is it about the Fiero V6 installation that is different enough that the 100's of failures that would be expected from a 7k sample size simply don't happen? Is it the iron heads? Aluminum intake manifold instead of plastic?

Sometimes I worry about my intake gaskets leaking, but I'm comforted by the fact that there is no history of my engine experiencing premature ingake gasket failures.

It's no better then a 3800. Plus, you can't get a
4.3 in a Lesabre.

I think its one of those things where there's sort of a cliff you can fall off of. Just the right amount of piston clearance, and all is quiet. A few thousandths looser, and its noisy as heck but not damaging (happens to any piston with forged pistons when cold, for example, and is why almost no maker uses forged pistons except in high-performance applications). A few more thousandths, and the noise doesn't sound any worse but the cylinders and pistons get chewed up much much faster.

GM's best engine: 3.4 or 3.8 ?

To return to your original question, none of the engines you mention are particularly unreliable. But the 3800 is by far the best of that stable. The 3400 will last a lot of miles, but those miles will be more pleasant with the 3800. It only has about 20 horsepower more than the 34, but it delivers a much stronger torque curve. Reliability and milage are not significantly different between them. But the "fun factor" is with the 3800. (if you want "real" durability, find an old Chysler slant 6)

I think you're right. I mixed up the 2. Thanks.

My '90 Grand Prix has had piston slap (I assume) since I got it. I used to think it was just the sound of the oil pump working. But I read about the slap and assume that is what's happening in my grand prix.

Honestly, I can't believe piston slap doesn't harm anything. But I've read about it being harmless in more than one instance. Granted, one instance was in a small engine repair manual (Briggs and Stratton).

Olds 350, Buick 455, or Cadillac 472.

Of the current engines, the 3.8 comes closest to the old v8s.

<Fiew that was a long discussion. Thanks for our input.

There's also the fact that the sort of driving he does is *ideal* for keeping any car going - plenty of time to warm up, few stops and starts and apparently no long periods of sitting inactive.