1995 Buick Riviera Supercharged from North America - Comments

When I first purchased this car it came with a 30 day warranty, and 50/50 with the dealer on parts and labor. I owned the Riviera two weeks when the instrument cluster went dead. I was told that I needed to install a new one which would cost $1,200 or a re-manufactured one at half the price. I opted for the re-manufactured instrument cluster and had the GM Service Technicians installed it. I've not had any further problems with it.

I've driven the car now for almost three years and noticed two weeks ago that I had a severe spark knock. I assumed I had water in the gas, since I had just filled the tank when I immediately noticed the dieseling. I added Alcohol to displace the water and found no change. I then thought that perhaps the injectors were dirty and added fuel injector cleaner. The dieseling got worst. I brought the car into the dealer for service the very next day.

I was advised that the #4 piston had burnt through! They performed a compression test and found that the motor was blown. They removed the head and found that the cylinder was out of round to the tune of 13 thousandths. The engine was beyond fixing and I ordered a remanufactured 3.8L for $2.900 including the installation. The engine comes with a three year 36.000 mile warranty.

The cause of the engine failure was diagnosed as inherent to the engine design. Exhaust gases are circulated around the front to the rear and both sides of the #4 piston, on it's way to the exhaust manifold. This #4 piston runs hotter than the rest and is more likely to warp.

I accelerated the process by using regular gas on rare occasions. So to all of you Riviera owners beware, fill your car with Super or it will cost you $$$

That is very informative. Thanks.

Does anyone know if there is enough/any room between the manifold, and the #4 piston.

So that one might be able to wedge some insulation in there to protect the engine.

Everyone should run their car on the highest grade possible anyways. IMHO.

I always say, check the manual to judge what fuel grade will best suit your car. It's the best way to know for sure. And a higher ethanol level could be damaging to some engines. Been there and done that when I filled my Toronado with a 3.8 engine with Super. The ethanol boiled in the fuel line and stalled until I drove the Super grade out and filled up again with 87 octane gas (regular unleaded). I checked the manual, and sure enough, it stated that GM reccommends no higher than 87 in my car. BUT, there are newer versions of the 3.8 out there, the requirements for fuel on those could be different. I believe when I looked at a new Chevy Impala SS with a 3.8 supercharged engine, it said premium only. Just kind advise: Read the fuel requirements in the owner's manual of your vehicle the very first thing after you buy it, and before you fill up for the first time. Use no grade higher or lower than the recommended grade.

I purchased my riv in 2003,it was a great car for the first year. after that it was all down hill I put over 6000.00 dollars. in this car in the past 2 in a half year's I owned it. my advice to all riv owners looks great, but get rid of this car.

One thing, I believe you are all missing:

The engine is computer controlled, or at least a ignition module system. A (Sync-Pulse) from the "hall effect" switch, to the ignititon module set's static timming, along with ECM, for spark advance. When you run a poor grade of fuel (low octane), spark knock, or engine ping, will occur. The (ESC) : (Electronic Spark Control), is used to sense the (pinging) and retard the timing to eliminate it. A knock sensor (located in the block) sends the signals to an ESC module which signals the ECM that engine knocking is detected. The ECM< should retard the timing, up to 20 degrees in 1 or 2 degree increments. With a loss of knock sensor signal, or a degraded ground, timing retard will not happen. It then raises the cyl. temp, forcing the motor into detonation. Engine failer, Yes to say the least. Matt

*1, Note: Once the octane requirements of the engine are satisfied, increased octane will have no beneficial effect on the engine...

Public service announcement:

If you can't afford premium in a premium only car put E85 into it.

It satisfies the octane requirements so the system can still work smoothly.

However the motor will get worse mileage and have less power.

Its perfectly safe don't worry.

(coming from a driver of a non flexfuel avalanche run on E85 for 200,000+ miles)

Filling a non flexfuel vehicle with E85 may damage fuel hoses and the combustion characteristics are different. I mean, if you want to fill up your riviera with E85 go for it; just be ready for some kind of failure that your mechanic has "never seen that happen before."

Dayfydd says: I have never had so much fun with a car... what a sleeper in the performance category; 0-60 in the mid 7's. They really slipped this one by the insurance companies. The Regal with the same 3.8 SC drive train is a full second faster because it's simply lighter.

Superchargers have about a 100K mile life if you use them. The transmissions are surprisingly tough and reliable given the torque they face on a full supercharged start.

Don't ever get in the habit of using less than premium gas on the supercharged model... you'll be sorry later.

The living room sized leather seats are so comfortable you may want to install your TV in your car instead of the house.

To those who like more radical styling, the Riv is poetry in motion... and for an almost 4000 lb car, its performance is unexpectedly full on fun. The handling is different, but a great compromise for a stylish European inspired luxury coupe trying to maintain a quiet and comfortable ride. If you think the maintenance is high, try Cadillac... you'll come back to Buick in a hurry.

The engine and seats have won numerous awards, except for the plastic intake in the 96-99 model year; that's a terrible mistake, that GM allowed the dealers to make a fortune on way too long.

But overall, it's been nothing, but a pleasure to own my 95 (with the metal intake) which I now have 160K miles on... and I'm seriously thinking of looking for another 95 with low mileage so I can take off where this one stops.

My 1995 Supercharged Riviera ran great until yesterday... I put normal grade unleaded into it and heard a terrible knock as I floored the gas pedal at around 65mph on the freeway to merge into traffic. Now the engine knocks badly, and there is aluminum looking metal on the oil dip stick. My guess is that I blew #4 piston as a previous writer suggested. Not too happy about having put unleaded in a car that specified super-unleaded. But it really should NOT have had such a negative effect, & with only 65,000 miles on this cream-puff of a car. I might rebuild the engine with bullet-proof racing parts and make it into a 1200 horsepower screamer! Do you think I can get Buick/GM to sponsor this modification?...Good luck to all. Oh, I am on the west coast and this all happened at sea level on a 75 degree day. BTW I had just driven through a car wash about an hour before this happened, don't know if this made a difference.