With all the engine problems the 3800 impala has had thus far, it got me wondering. Why is the 3400 engine viewed as somehow inferior to the 3800? I bet most 3800 owners never drove one and only base their opinion on internet hype.


So far, my 3400 has only needed plugs, wires, and oil and filters. Never needed a single gasket replaced, except the throttle body gasket due to cleaning. With the FWI, it runs even better... dare I say comparable to the 3800, but more smooth... No ticks, no rough idle, no drone.
It just runs. I can even pass at 80+ up a very steep incline. The best part though, if I keep my foot out of it, I can pull 30+ mpg (when my cat wasn't clogged). I switched to full synth oil at 127,xxx and haven't had a drop of oil leak in the 4k+ since. I'm not gentle to this engine either, I'm much harder on it than she is on the 3800. In my experience, the 3400 engine has been bullet proof. Other parts on the car not so much (brake lines, ign cylinder)

The 3800 has needed: upper intake gasket(2x), lower intake gasket, plenum gasket (Ithink), coolant elbows, multiple water pumps, throttle body gasket, MAF sensor, multiple starters, multiple oil level sensors, and it's going to need an alternator soon. It's also magically "using" a quart of oil per change, with no external leak. The 3800 very mildly faster, probably so it can make it to the mechanic quicker

The gaskets were likely due to red coolant, however the 3400 had red coolant for 40k more miles, with the original, without a problem.


Basically, I'm wondering why the 3800 is generally more highly revered, while it has so many potential weak points? A trusted mechanic (ex gm tech) has told me it's pretty rare for a 3400 to have gasket issues. He's seen a ton of 3800s having gasket issue.

I'm not trying to start an engine fan war, if that's even a thing. I'm honestly wondering.

The 3800 just shut off on her while riding on a 4 lane, which could have been fatal. It's down again with a rough idle/no start issue. I'm almost ready to convince her to sell the thing and get a monte (5.4, 3.5, or 3.4)

 

Don't have a answer to your question, as I didn't car shop for my Monte. It drove into my driveway and offered to me first and I couldn't pass it by.
I have had the gaskets done, have the mystery oil issue, and a intermittent starting issue.

I don't think you are starting a engine fan war, this was a well written statement to start a discussion. I hope others will engage in it

 

Luck of the draw, the 3800 is a bulletproof reliable engine and the 3100/3400 are right there too with being good engines. Sometimes you can run them forever with basic maintenance, other times they become needy.

 

People look down on the 3400 because it's not as big as a 3800. Most, if not all, of the high HP w-bodies run 3800s. You can just get more power out of it, especially with the limited aftermarket for the 3400. I will say that although my 3800 is tons faster than my old 3100, the 60* sounded SWEET.

Reliability though? Comparable, in my opinion.

 

I have worked on many 3800 and the 3100/3400 engines. All of them have lower intake gasket issues. And don't believe the hype about Dex cool, the root cause of the lower intake gasket failure is nylon gaskets, even the trusty green stuff causes those babies to fail. I've done LIM gaskets on both the 3800 and the 3100/3400. I find the 3800 easier/quicker to do.

I have love for both engines. I have my '04 Monte with a 3800 and my '04 Grand Am with a 3400. And I've done modes for both cars. My ex-wife also had an impala with a 3400. The 3400 is great in the N-bodies (smaller/lighter cars and can give stupid quick acceleration). In the wbody, I feel the 3400 holds up nicely, but the 3800 puts out more power and torque and handles the larger/heavier car better.

Most 3800's are bullet proof and basic maintenance, they last. But like anything, you can have that one that was bad luck. As for some of the recalls on the 3800, I believe the valve cover issue is simply that it's old and like anything it can have problems. The valve cover and gasket design used on the modern 3800 has existed since '93 or longer.

Performance companies worked with the 3800 more because of more options. Such as GM has a supercharged 3800, so it can be boosted from the factory and that can impact mod plans (the 3400 to my knowledge was never boosted from the factory). Plus the 3800 is actually based of the Buick v8 from the 60's (the 3800 has been around decades, sometimes it was simply a 3.8, such as the 3.8 in the Buick Grand National is part of the heritage to the 3800).

The 3800 for quite some time was ahead in HP and torque over the 3100/3400. As I recall GM was planning to end the 3800 in 1999, but consumer demand kept it going. I speculate GM was finding the 60* engines were finally catching up in performance (as the 3100/3400/3500/3900 I believe are all based off the same block design).

I prefer the 3800 over the 3400 in general. I like it better. But there is NOTHING wrong with a 3400. I feel both have very good reliability and reasonable performance.

 

I agree with Jason hands down. Main reason I prefer the 3800 though is what 3400 ever made 594whp like my 3800 currently is? And my 3800 is still not maxed, going to try and hit 700whp possibly this winter.

 

I believe the first 3800 that I was in an Oldsmobile in 1987 touring Sedan that a friend of mine owned it was fast and he had very good luck with it.
When it was time to replace the car that I had for business work I found a 1990 Oldsmobile got it when it had 45K on it and I drove it to 389K then the computer went out and the service tech I used said probably not a good idea to replace the computer.
I found several more that had the 3800 in it and with normal maintenance it lasts and lasts.
I have had the 3400 in Pontiacs and they do well also. I have a 3400 in the Pontiac Torrent that I own and it has not performed as well as the others I have had. But the main driver is my wife so I will have to say there is a 50/50 issue there?


The 95-97 Monte Carlos had the 3400 in them, most of them had minimal issues but the big complaint I had heard about was the location of the alternator and it took more labor to pull and replace.
I agree with all the other replies your gonna get a bad one now and then.

 

Both are excellent engines in my mind - I've had many of the 60* engines 2.8, 3100, 3400 and multiple of each (save the 2.8). I have also had several 3800s and variations to it: L26, L36, L67. I've had these setups across multiple platforms - w, f, n, and across decades - 80s, 90s, 2000s cars.

Anyway, as far as mpg - I can average 32 or 33 mpg on my 04 GPGT (3800 Series III N/A) and I got a crazy 38mpg but that was some serious hyper mileling down I-45 all HWY - feather pedal, not accelerating at times and allowing the car to coast up (slight) hill, allowing the downhill to pull the car, note that this was all done safe and few cars on the road so I was not a hazard - Also this is not typical driving habits for me - just went to see what I could get.

My 05 Impala 3400 can get an average of 33-34 highway as well. I have modest driving habits and I am generally 'nicer' to my vehicles than the average gun-it-off-the-line people I see driving.

*All mileage is calculated via miles driven to gas in the tank and I typically fuel at the same fuel station and pump.


As with any driving you can seriously alter mpg based on driving habits/conditions.

As far as maintenance, there are some things easier on the 3400 (things like water pumps) and some things easier on a 3800 (t-stat).

 

Sounds like you got a bit unlucky for maintenance on your 3800. I've had 5 cars with a 3800 (currently still own 2 of them), and have had very little maintenance cost on any of them. The worst maintenance I had to do was an upper intake manifold replacement on my 03 Impala, but I think even that was only about $125.

That's not to say I had bad luck on the 60 degree engines either. My monte had a 3100 for about 100k miles with the only unusual maintenance being intake gaskets (again, super cheap, easy fix). Everything else was just the typical stuff on either engine - plugs, wires, oil, alternator, etc etc. But that's all stuff I'd expect from any engine.

My big reason for swapping the 60 degree engine out for a 3800 was for more power and more aftermarket. At the time, there was virtually no aftermarket for the 60 degree engines. Certainly it has picked up a bit now, but the 3800 just has so much more aftermarket support.

Plus with a NA 3800, you can top swap it with the supercharged 3800 top end for dirt cheap and pick up a pretty significant amount of power for the money.

 

Both great engines IMO . Even the 4.3l and v8 of the same era have intake gasket issues. Ive owned 2.8 and 3.1 in the past and both were good to me as well...