Hi I have a 2000 Buick park ave v6 3800 series and the problem started as a small leak in the radiator from the little drain plug so I righted that and the leak moved to the whole opposite side of the radiator then I put stop leak in it (Polly my first n worst mistake) and it ran fine for like two hours then overheated and started making noise as if there was no oil in it and shut off while drivimg on freeway so i I checked oil let it cool down. Oil was low, I put some in then started driving home which was only like 4 miles and as I got about 300 yards from my driveway it stop as engine light came on and now it Bailey wants to run as over flow bottle boils with engine light on and slowly but surely gets hot. Can u help and please diagnose this problem and give me a rough estimate of labor costs and labor it will take to fix am I better off replacing motor as this one has 265,000 miles or should I buy new car. Thanks '
This is a bit difficult to diagnose over the internet, but it sounds like you have a coolant circulation problem as well as a pretty bad oil leak. I would take it to GMC or Chevrolet and pay them to diagnose it. It only costs $100.00. A skilled tech can tell you exactly whats wrong with it and how to go about fixing it. If it's a head gasket (Which it sounds like it might be), get rid of it and buy a new car. There are many things that can cause a car to overheat and leak oil. The 3800 in that car is very resilient, however one of the most common problems with them is head-gasket failure. I've changed many in my career, and it costs a lot of money for the costumer.
I would still take it to someone to be looked at professionally. It could be as simple as a coolant leak, and your oil was conveniently low at the same time. I hope you get it figured out!
A couple of tests you can do to help determine what is happening.
Compression test. minimum 120 psi, should all be within ~10%
Oil and coolant are mixed. Check oil and coolant.
Exhaust smells like coolant or burning oil. Might smoke excessively
Bubbling in the radiator while running.
Check plugs for oil/coolant.
First, fix all leaks. it will never be right if there is a visible leak
Radiator pressure test to determine if the system can hold pressure. If not, should help to point out the leak.
Alternately, let the engine get hot and feel the upper radiator hose, it should be stiff with pressure.
Cold spots on the radiator - the 'stop leak' could had caused a clog
Stuck thermostat - heat, radiator hoses cold
Bad water pump - no heat, radiator hoses cold.
For a clogged rad, or stuck thermostat, running the heat full blast should help keep the engine cool.
I'm sure there are a few things I missed, but that should give you a good idea. At least look into it a bit before you trash it. No sense buying a new car/engine if you can fix what you have for cheaper/less work.