2002 Buick Lesabre Engine Explosion

5

Asked by Nov 30, 2016 at 09:23 AM about the 2002 Buick LeSabre Limited

Question type: Maintenance & Repair

I have a 2002 Buick LeSabre with 123,000 miles. The car was in excellent
condition. One day, I went to start the car and there was a loud explosion
under the hood.  The engine ran, but it raced at very high rpm's  almost as
though it was running without oil.  As soon as I touched the gas pedal, the car
stalled out. I opened the hood to find the oil filler cap busted off of the plastic
filler neck and the plastic intake plenum  shattered to pieces. I also noticed
what looked like oil leaking out from around all the heads. Not from the valve
covers, but leaking from the heads. I can still start the car, and it will still run,
but again, it runs at very high rpm's and if I touch the  accelerator, the car
stalls out.  Someone suggested to me that the engine might've jumped the
timing chain, but I don't think that's what happened.

My question are these:

What happened?

Why the explosion out of nowhere?

Can the engine be repaired? If so, how much on average? Or does the
engine need to be completely replaced?

9 Answers

100,445

This sounds like the explosion happened in the intake system causing the manifold in to crack and break, this will also explane th high engine RPM's, it is taking in to much unmetered air. I believe that it can be repaired with new parts, but you will still need to find out why it backfired through the intake or it will happen again, it is possible you could have leaking injectors and the fuel fumes from seeping up from the crankcase ignited in the intake system, but you won't really know until you fix the broken parts and go from there, I am going to estimate at a minimum about 750 bucks, hard too give an accurate estimate as I can't physically see the problems.

Best Answer Mark helpful
5

I'm also trying to understand pressure inside of the engine so intense that it would blow off a tightly fastened oil cap and make the heads leak oil through the gaskets. Any idea on that?

100,445

Gasoline explosions can be powerful, I have seen it blow off metal valve covers, metal oil pans, bust plastic intake manifolds into fragments, so its not really that surprising.

5

So I guess the bottom line is tow it somewhere, have it looked at and see if it's salvageable? Or do you think a new engine would be more cost effective?

100,445

A good independent shop would be a place to have it towed and looked at, they would be your best bet on determining if the engine needs replaced or if it can bet fixed. It all depends on the overall condition of the car.

5

The car is in excellent condition, physically speaking, both inside and out. I bought it for an elderly uncle several years ago and he passed away last week. I got in the car to start it up because I intended to take it back and keep it as a second car, but now I'm wondering if it's even worth the expense. I understand the GM 3.8 from 1996 through 2005 had a plastic intake plenum prone to failure and I wonder if this might be the cause of this entire problem, I just can't see how the intake failure would create so much internal pressure as to bust off the oil cap and make the head gaskets leak. I'm also not sure what other damage has been caused. It's hard to tell.. Probably not worth investing the money into it, but a shame nonetheless because of how pristine the car is.

100,445

It most likely was not the cause of the explosion, like I stated earlier that you could have some leaking injectors, that fuel can go down the rings and fumes can come up from the oil pan and fill the intake areas with fumes and then all it would take is one stray source of ignition say from normal valve overlap and bang you have an explosion. If you really want to keep the car you might consider a good used engine, one with a warranty, at least that way the engine will be covered but not the labor.

100,445

Thanks for the points.

10

i have a 97 lesabre and the fuel pressure regulator failed causing the intake and all cylinders to fill with fuel. lucky for me it hydrolocked. i removed the intake plenum and sucked the fuel out of the intake ports. i also removed the spark plugs and cranked the engine over to remove the fuel from the cylinders. if it had tried to start it would have caused a huge explosion. this may be what happened. i can certainly understand leaking head gaskets and the plastic intake blown apart. if you replace the engine make sure to replace the fuel pressere regulator on the fuel rail or it will happen again. that would suck!

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