2002 Buick Century, lacks power, poor gas mileage.

[Century]

Greetings!

I am about to purchase a 2000 Buick Century Limited with the 3.1L V6 engine with 79,000 miles. Is there any way to tell if the intake manifold gaskets have already been replaced? If not, what are the chances that I'll encounter a failure? Anything to prevent failure? What would be the approx. cost to replace intake manifold gaskets? This information or any other information related to this car would be greatly appreciated! Thanks. Scott

[MeccBoy]

No good way to tell if they have been replaced for someone who has not worked on these cars for years. You could look at the corners of the lower intake manifold to see if they are leaking. Look closely at the bolts heads for the upper and lower intake to see if they show signs that a socket has been on them- which would indicate the manifold had been removed. Take the oil fill cap off and see if the underside of the cap or the inside of the valve cover has a "milkshake" residue on them would indicate the gasket is currently leaking.
Approximate cost depends on the repair shop. At the dealer, expect to pay $700-$800.
A local repair shop would save you maybe $150 just because the labor cost is lower.

[Century]

Got the car. It's in amazing condition! No leaks that I can tell. Would like to use Mobil One Synthetic 5w30 High Mileage formula. Any thoughts?

Thanks

[Century]

I did purchase the 2000 Buick Century Limited! Love it! I am amazed at the condition (even before I did a complete interior carpet clean, etc./leather clean/buff, AND exterior machine buff and poly seal. The car feels like it has 20, 000 miles, not 79,000. Super clean under body too! Loaded to the max, I'm calling it a "baby Cadillac!"

With that said, I'd welcome advice on changing the oil. I've been told that "Mobil 1 High Mileage 5w30" would be the best choice for this Buick. Please tell me your opinions. All very much appreciated!

Thanks,
Scott

[Stannllee]

A synthetic oil is not really necessary. I have worked on many GM vehicles that have had only conventional motor oil and they have lasted for years and years and over 200,000 miles. It all depends on how well the car's been take care of. Has all the maintenance then done, have any repairs that were needed been done in a timely manner to prevent causing further problems. If you do want to use synthetic motor oil, then that mobile one high mileage would be your best choice.

[wildman]

I will add that when winter is over you probably need to watch the oil pressure. Winter thickens the oil, but when the motor is hot or the weather stays warm you may notice the pressure and need to run a little thicker oil. This is because the pressure is made by forcing it through the engine components- but over time wear increases the passages. I don't suggest running 20w50 because it can actually strain the oil pump, but from my experience the harder run vehicles show less pressure.

And synthetic oil is nice- if you want to pay the price, but not necessary. Much of the oil you buy have the same additives and such as the synthetic. I have only run it once- only because the dodge smoked a little and I was tired of seeing it.

[goatman]

2002 Buick Century 3.1, 150,000 miles. Had EGR codes P0401 + P0404 back in July, but car run fine + had power. Replaced EGR valve back then. Codes are back on + car lacks power, no get up+go. Pulled throttle body + cleaned out EGR port, Was clogged. Cleared codes. Checked fuel pressure. 52lbs with key on,engine off. Cars still lacks power, eats fuel. Could catalytic converter be clogged + causing this? How do I check it? What else do I check. Did tune up about a year ago.

[TerryAuto]

Yes, you could have a plugged catalytic converter. They can also set EGR codes. The proper test is to use a back pressure gauge in the oxygen sensor port. But, you can unbolt the exhaust at the rear manifold from under the car, ahead of the converter then see if power and acceleration is restored.

You could also have a faulty MAF sensor. You would need to look at airflow readings of MAF to see if they increase as RPM increases. You can also unplug it when it is running, if it dies- restart it, then see if power is back to normal.

I would also check the fuel pressure regulator. If it was leaking, that would cause the very bad gas mileage, and could be the cause of a plugged catalytic converter.

[goatman]

Will be disconnecting cat tomorrow to see if that helps. Thanks.

[TerryAuto]

Will be disconnecting cat tomorrow to see if that helps. Thanks.

Please let us know what you find.