3.8 2001 Monte Carlo

Ndx

Messages
1,875
Location
IL
Hi Guys, Are they are known problems on those engines ? Leaking Cover Gaskets ? Head Gaskets ? Thx K.
 
Messages
10,008
Location
Upstate NY
Upper intake manifolds can grenade very rarely. More common are the lower intake manifold gaskets failing, or the upper intake manifold burning a hole near the EGR gas stovepipe that runs through the plastic upper intake manifold. Symptoms of the above are the car suddenly starting to lose antifreeze with no external leaks. Usually they start to go around 100k miles or so. Replacement is DIYable with a good guide, of which there are several on various forums. Otherwise it's lots of money at a mechanic. Valve cover gaskets are known for leaking, but that isn't serious. Head gaskets are not a concern. Enjoy the car!
 
Messages
432
Location
central Georgia
Agreed. Upper intake manifold coolant leaks. Watch the reservoir like a hawk. Many of these plastic intakes have date codes stamped in the top- good way to know if it's been replaced. I think the fuel pressure regulators had a recall during that time period too (easy to fix).
 
Messages
935
Location
MI
There are gaskets out that fix the problems. So once they are replaced you don't have to deal with them again.
 
Messages
21
Location
Kalifornia
My 96 LeSabre with the 3.8 Series 2 had a coolant leak that ended up being the plastic intake warped and started leaking. It has never been hot so I dont know why it warped. Parts guy said almost all of the 3.8 mainfolds leak at one time or another. Of course mine only had 150K on it so I guess it was time. About one year later the oil pressure switch started leaking real bad. Replace the OP switch only with the OE switch. Aftermarket does not work. Engine now has about 165K and runs like new.
 
Messages
10,008
Location
Upstate NY
Something to buy you more time on the gaskets and get a bit more performance out of the car in warm weather is replacing the stock 195* F thermostat with a 180* stat. Heat and pressure make the gaskets fail, so reducing the heat is good. With the stock 195* stat coolant temperatures around 200* and above are common. The stock computer trips the fans at 212*, which is easy to see in stop-and-go city traffic during the summer. Also, running the A/C automatically trips the fans regardless of coolant temperature. I've been running a 180* thermostat in my 99 LeSabre for a year now with no ill effects. The heat in the winter is enough to roast a chicken, and the motor warms up quickly. Another place for a slow coolant leak that will drain the overflow tank in a month and result in poor gas mileage is a bad radiator cap. Mine went on me around the 9 year old mark, and I could barely get 25 mpg highway. A new radiator cap cost $5, and a system pressure test to rule out gaskets was $50.
 
Messages
887
Location
LI, NY
 Quote:
Another place for a slow coolant leak that will drain the overflow tank in a month and result in poor gas mileage is a bad radiator cap. Mine went on me around the 9 year old mark, and I could barely get 25 mpg highway. A new radiator cap cost $5, and a system pressure test to rule out gaskets was $50.
How will a bad radiator cap result in bad mileage?
 
Messages
10,008
Location
Upstate NY
Doesn't allow pressure to build up in the system, so the coolant can't carry as much heat, so the engine runs too cool? IDK, just that 1 part being replaced made my gas mileage and heat better. But it did cause my slow coolant leak to disappear. That's the one hard fact there.
 
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