Any problems noted with new 3.5/3.9 engines?

Have had 3.8 all iron engines in my last 3 GM cars and was very satisfied with them. Am now trying to decide whether to try the 2007 Chev LT with the 3.5 or 3.9 or go with the Buick Lacrosse and stay with the old reliable 3.8. Would appreciate any thoughts regarding the economy/reliability of the 3.5 or 3.9

Thanks, Tugboat Sailor, ATF 91

The 3.5/3.9 are still pushords right? Are they the same as the 3.8/3.4 just bigger?

5 seconds on Google:
SPECIFICATIONS: 3.9L V-6 (LZ8)

Assembly site:
Tonawanda, NY

Application:
Chevrolet Impala

Type:
3.9L V-6 with variable valve timing, Active Fuel Management™ (LZ8)

Displacement (cu in/ cc):
237 / 3880

Bore x stroke (in x mm):
3.90 x 3.31 / 99 x 84

Block material:
cast iron

Main bearing caps
powder metal (1, 2, 3); cast nodular iron (4)

Cylinder head material:
cast aluminum

Intake manifold:
cast aluminum

Exhaust manifolds:
high-silicon molybdenum, cast nodular iron

Compression ratio:
9.8:1

Valve configuration:
overhead valves (2 valves per cylinder)
Valve lifters:
hydraulic roller

Firing order:
1 - 2 - 3 - 4 - 5 - 6

Fuel system:
sequential fuel injection

Horsepower (hp / kW):
233 / 174 @ 5600 rpm*

Torque (lb-ft / Nm):
240 / 325 @ 4000 rpm*

Fuel shut-off:
6400 rpm

Emissions controls:
close-coupled catalytic converter, evaporative system, positive crankcase ventilation

Crankshaft:
steel

Camshaft:
assembled steel

Connecting rods:
forged powder metal

Additional features:
electronic throttle control, dual equal continuously variable valve timing, roller rocker arms, pressure-actuated piston cooling jets, extended-life spark plugs, extended-life coolant, GM Oil Life System, oil level sensor, extended-life accessory drive belt


SPECIFICATIONS: 3.9L V-6 (LGD)

Assembly site:
Ramos Arizpe, Mexico

Application:
Chevrolet Uplander

Type:
3.9L V-6 with E85 ethanol capability ( LGD )

Displacement (cu in/ cc):
238 / 3880

Bore x stroke (in x mm):
3.90 x 3.31 / 99 x 84

Block material:
cast iron

Main bearing caps
powder metal (1, 2, 3); cast iron (4)

Cylinder head material:
aluminum

Intake manifold:
cast aluminum

Exhaust manifolds:
high-silicon molybdenum, cast nodular iron

Compression ratio:
9.8:1

Valve configuration:
overhead valves (2 valves per cylinder)

Valve lifters:
hydraulic roller

Firing order:
1 - 2 - 3 - 4 - 5 - 6

Fuel system:
sequential fuel injection

Fuel type:
E85 and regular unleaded

Horsepower (hp / kW)
240 / 179 @ 6000 rpm*

Torque (lb-ft / Nm):
240 / 325 @ 4800 rpm*

Fuel shut-off:
6000 rpm

Emissions controls:
catalytic converter, evaporative system, positive crankcase ventilation

Crankshaft:
steel

Camshaft:
assembled steel

Connecting rods:
forged powder metal

Additional features:
E85 flex-fuel capable, 58X crankshaft, cam phaser, U-flow cooling

another 5 seconds on google:
Date Posted
02/14/2007 Unhappy by Chuck
Style: LTZ 4dr Sedan (3.9L 6cyl 4A) Rating 6.5

Review: Vibration and noise thru-out car plus tire pressure monitor system gives false reading. GM has worked for a year and still has no fix for the Vib/noise problem. I was not aware of the problems plus the dealership did not disclose the problems prior to me accepting/paying for the car.
Suggested Improvements: Do not sell cars to consumers with known problems that GM has no fix for.

Date Posted
01/05/2007 Love my LTZ by Bob
Style: LTZ 4dr Sedan (3.9L 6cyl 4A) Rating 10.0

Review: Just picked up my 2007 LTZ and so far have been extremely impressed. The car is tight and quiet with amazing acceleration! My only compliant is that for a vehicle of this price, I cannot believe that you cannot get climate control. Other then that I love the LTZ!
Favorite Features: Love the acceleration of the 3.9 liter engine

Date Posted
01/02/2007 Improving GM Designs by Todd
Style: LTZ 4dr Sedan (3.9L 6cyl 4A) Rating 8.6

Review: Overall, the 2007 3.9L Impala LTZ compared well with the our previous GM car, 1998 3.8L Lumina LTZ. The engine performs well with nice pickup, but sometimes lugs down in 3-cyl mode before switching. With 4000 miles on car, the average fuel economy for 87 octane fuel is 20 mpg for combined city/highway driving, which is alright but not a good as expected. Engine access for maintenance work is much improved. The car does sound to be less sound proof than older car with noticeable wind and road noise, not sure if this is due to rear-door driver-side alignment.
Favorite Features: Much improved interior robustness and styling. Very thankful of improved trunk design tons of space and rear seat access. Love the heated seats and firmness of the car on the road. Auxillary input jack for stereo for iPod use. Digital driver information center.
Suggested Improvements: More sound proofing material in doors and engine compartment with improved door design reducing road noise. Smaller footprint for front power seats giving more rear foot room. Additional front cup holders.

Date Posted
12/28/2006 Good Replacement Choice by BobH
Style: LTZ 4dr Sedan (3.9L 6cyl 4A) Rating 8.8

Review: I never rate anything a 10! Only had this car for 7 weeks - 1600 miles but so far am well pleased. Fully loaded. Imperial blue/gray interior. 20 - 22 mpg with very little highway driving. Leased 3yr/36000mi. Selected for style and features to replace a 99 300M. Great trunk space for 4 golf bags. Quiet riding. Suspension seems a little rough on minor road bumps and seems to hesitate a bit when going from 3cyl to 6 cyl mode in city driving but overall driving is a pleasure. I'm a large sedan type of a guy and this was a good choice especially with the lease incentive and rate and my GM Mastercard rebate.
Favorite Features: Exterior/interior look and style. Large trunk. Daytime running lights. Great sound system. Good mileage.
Suggested Improvements: Definitely automatic climate control and rear vents would make it a true top of the line sedan. Move the sunroof opening into the headliner area instead of exterior for a sleeker look when open.

Date Posted
12/06/2006 Not as good as 2000LS by Cam
Style: LTZ 4dr Sedan (3.9L 6cyl 4A) Rating 6.5

Review: Had a 2000LS (Great car) and so I bought a 2007 LTZ. The 2007 car is smaller and the back seat has little leg room, leather seats are not comfortable, back seat sholder belts are ratchet type and close to smallest size and won't relase without releasing the belt(everybody that uses these complains there too tight) I'm getting 16 to 19.5 MPG which includes 25% highway driving and 3 cylinder engine mode( I'm an easy driver and this is much worse then the 2000) The outside mirrors are smaller and have a bad blind spot,(beyond me why they don't incorporate a small wide angle mirror into the rearview and why the insurance companies don't promote this). Make sure the car serves your needs!
Favorite Features: XM radio/cd/ MP3 radio together with the Bose speakers is nice. Various upgrades are nice. I would have preferred the option of getting the E85 engine like the LT3 has. Also you have to get a sun roof on the LT3 to get the outside heated rearview mirrors and I did not want a sunroof.
Suggested Improvements: Improve engine efficiency (go back to the 2000LS design it is much better) Use the front seat tension design in the rear seat belts. Make the car bigger like the 2000. Put wide angle spot on outside rear view mirrors. Provide option of E85 engine.

Thanks for the gogle searches, but I think the OP was looking for a more general opinion on the new Engines.

My point was to keep googleing, I just did a real quick search. A more extensive google search would probably turn up plenty of info. I believe the two engines in question are too new to have much of a track record unless you consider the fact that they may be similar to the 3.4 and the 3.8 and then you can just refer back to their history which is somewhat storied but the issues have been getting worked out. I suspect that the new engines will be very good indeed.

It's hard to tell this early in their life cycle. The 3.5 is based off the crappy and problematic 60 degree pushrod 3.4 that was in the last base Impala. The 3.9 is an enlarged 3.5 . These are in no way related to the wonderful and reliable 3800, which is a 90 degree motor.

Having driven Impala's with both the 3.5 and 3.9 ( and the old ones with the 3.4 and the 3.8 ), I must say that in terms of driveability, the new engines are much better than the 3.4. BUT I love the 3.8 still much better and would trust it's durability than I would an engine with aluminum heads and an iron block. Just my 2 cents.

Also, I remember reading in the newspaper that they tested an 06 Impala and at 30,000 miles, the waterpump on their 3.5 died. Time will tell if the 3.5 and 3.9 are any better than the problematic 3.4 they are based off. Too bad GM's ending 3800 production next year.

Back to the Tire Monitoring System: I have had this 2007 since it was new and haven't had any problems, but recently, I am constantly seeing that the Tire Pressures are bad! Does anyone know if there has been a fix for this??? Or a way around this problem. It is really annoying! Thanks!

Only the 2004 - 06 LX9 3.5 was truly based on the 3400 series. The LZ4 and LZE 3500s are based off the LZ9 3900, which it self may be a relative of the 3400, but is a VERY different animal.

-yay for not reading post dates....