teach me all about the 3400 V6

My mother's 2003 Rendezvous just crossed the 100,000 mile mark and after replacing the waterpump, hoses, thermostat, and belts, we have started to notice other little issues cropping up. It needs shocks and struts, I need to fix a rear window that won't stay up, and the airconditioning unit is making noise.

None of that would bother me if I don't need to worry about the engine. This is a "babied" engine, it has been on more than a few long trips and I occasionally wring it out to keep it all moving. It gets new oil ever 3000 to 4000 miles, and everything gets checked with each fill up. What issues should we be worried about? If a new engine is on the horizon, my Mother is not against a newer car, but does love her buick.

As long as all the gaskets are still in good shape, there are no known issues I'm aware of with the engine.

Checking the oil often is the best way to diagnose an early gasket issue and fix it before it takes out the engine. Changing the UIM and LIM gaskets is not a terribly difficult job. (those are the known failure points, but are much improved from earlier GM 60 deg V6es).

Most common issue is intake manifold gaskets failing, otherwise they are pretty reliable engines. Seen quite a few go past 200,000 miles with just basic maintenance.

I know f23 5 speed & 3500 lx9 heads and manifolds bolt up for a little more oomph... But probably not what your looking for on this one

sassyness77 wrote: I know f23 5 speed & 3500 lx9 heads and manifolds bolt up for a little more oomph... But probably not what your looking for on this one

And the U-body van was offered with a manual in Europe (although I'm not sure how well those parts would line up in a Rendezvous).

so I think this spring I will have the manifolds done as insurance. I do not need my almost 70yo mother having issues when she runs to the store or to the art gallery where she works once a week. It's been a very good van for her. No issues aside from tyres, oil, and other routine maintenance in the 50,000 miles she has owned it. It's just the little things that are starting to rear their ugly heads.

Certain things about it are aggravating to work on. Once the lower intake gaskets are replaced (which usually entails replacing some other wear item stuff as well) they are reliable. I dislike them because of the things about them that are hard to work on that should be easy, but realistically they rarely need work. Just typical water pumps and alternators and belt tensioners and thermostats which are all normal to do for the most part. The water pump is actually exceptionally easy.

mad_machine wrote: so I think this spring I will have the manifolds done as insurance.

No, don't do that unless you are bored and love working on cars just for fun. The manifold gasket(s) won't fail catastrophically and leave your mom stranded - they start as a seeping leak and gradually get worse. Just pop the radiator cap every few months and make sure the coolant level isn't dropping (you can't trust the overflow tank level). Don't fix it 'til it's broke!

Other than the UIM/LIM gaskets, 81cpcamaro is right: the 3400/4T65E is a pretty stout drivetrain. The rest of the car will gradually fall apart around it.

Sources: personal experience with 2001 Montana, 1999 Century, 2004 Rendezvous (which hasn't leaked yet, knock on plastic) and a buddy who is a tech at a Chevy dealer and has done more intake manifold gaskets on 3400s and 3100s than he cares to remember.

My family's owned about a dozen vehicles with the 3400 and its relatives. Only three have needed the gaskets done, and only one of those was actually a 3400. It was an '00 Impala and it failed under warranty.

As far as the rest of the Rendezvous, I've found that cheap aftermarket GM parts are absolute garbage. Strut mounts that failed in months, etc. It was worth it to buy OEM, or similar just to avoid the constant replacements.

If you do replace the intake gaskets, get the ones with steel carriers instead of the composite ones. The composite part is usually what fails and allows the rubber sealing rings to leak.

as Much as I do not mind working on cars, I just do not have the time to do it. I worked parttime for years and had plenty of time to do upgrades and upkeep, but those days are past. I will pay the mechanic down the road from me a few hard earned dollars to do the work. Just looking in the engine bay of the Rendezvous makes my back spasm, getting at those hidden bolts on the far side of the intake cannot be easy.

You mean like the stupid bolts holding the coilpack bracket down? I think you're doing the right thing avoiding this work if you don't enjoy working on cars or love this particular car.

I guess i had the misfortune of being spoiled by the Chrysler 3.3/3.8s i owned. They're even more reliable and much easier to work on.

I actually have a cousin who had a 3100 car for a long long time. I got tired of working on it, and when it needed LIM gaskets i convinced him to sell it and buy a Chrysler 3.8 van instead.

Just do what GM does, drop the engine cradle out from the bottom and fix the gaskets.

My son has my wife's old Venture. It's sitting at 250K on the original engine and transmission. The van is falling apart, the transmission is starting to shift a little funny, the engine is as stout and quiet as it was when we bought it. As mentioned above, keep a reasonable eye on the coolant. It it starts using it or turning gross, then do the intake gaskets. Having done them twice, it's not a job I would do for fun.

I've had a couple 2.8/3.1s but no 3.4s so I can't speak too intelligently since I don't know what all changed. But, the only ones we ever had in the shop were for gaskets and the like. They seem to run a very long time.

My 2.8L had 235k with almost nothing done to it except intake gaskets, a coil, and a rear main seal when I did the clutch. My 3.1L I only owned until 85k, but it never needed a single thing.

Use the nicest gaskets fel-pro sells, if it's like the 3800, they'll have aluminum frames rather than the stock plastic.

The GM 60 degree engine is one of my favorite designs. Light, compact, and easy to maintain. Being stuffed sideways into a van does complicte matters though. Outside of the intake gasket, they are good for a very long time with standard maintinence.