i replaced my radiator, radiator sensor, and thermostat, and my cars keeps running hot and coolant going down slowly. Why?

Asked by Jan 19, 2017 at 10:27 AM about the 2002 Buick Regal LS Sedan FWD

Question type: Maintenance & Repair

10 Answers


have your car pressure tested your water pump may be leaking while running and not circulating coolant properly. you may also have a leak in the intake or possible head gasket problem ? is the oil milky?

1 of 1 people found this helpful.

Not sure, it looks regular.


Did you purge the air out of the cooling system when you refilled it?

1 of 1 people found this helpful.

LOL, i don't even know how to do that.


Ok, remove the radiator cap. Start the engine to warm up to operating temp. Have the heat set on hot. The engine will run threw this process until you put the radiator cap back on. As the engine is warming up it may push coolant up threw the radiator and spill out, that is the air working it's way out. Once the coolant level drops in the radiator add more coolant to bring the level back up. This will close the thermostat until it heats up again to open. Keep doing this, 2-3 times and the air will be purged out. Top of the radiator and put the radiator cap back on with the engine running, once the cap is back on then you can shut down the engine. It helps if the front of the car is raised up or on a incline as air bubbles float upwards. Make sure you have at least a gallon of coolant when doing this.

1 of 1 people found this helpful.

I did this, and now my car is doing this weird thing were its fluttering while I'm driving, its almost like a skipping, as if its about to cut off and it did cut off yesterday while driving. It started back up but it keeps doing it. When it flutters/skips the rpm hand jumps as if I'm flooring the gas. Please help!!


Go to Auto Zone and have the codes read. Write them down and post them back here. This will give me an idea on what going on.

O2 sensor or cat converter.



P0420 BUICK - Catalyst System Low Efficiency Bank 1...Possible causes; Three way catalyst converter Bank 1, Exhaust tube, Intake air leaks, Fuel injectors may be faulty, Fuel injector leaks, Spark plugs may be faulty, Improper ignition timing, Powertrain Control Module (PCM)....As the code description implies the P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first.

Your Answer


Looking for a Used Regal in your area?

CarGurus has 234 nationwide Regal listings starting at $7,495.

Postal Code:

Buick Regal Experts

  • #1
  • #2
    Tom Demyan
  • #3
View All

Related Models For Sale

Used Chevrolet Malibu
99 Great Deals out of 1,769 listings starting at $888
Used Chevrolet Impala
179 Great Deals out of 1,062 listings starting at $2,454
Used Honda Accord
69 Great Deals out of 1,187 listings starting at $1,888
Used Cadillac CTS
21 Great Deals out of 378 listings starting at $2,500
Used Ford Mustang
6 Great Deals out of 1,033 listings starting at $3,995
Used Chevrolet Camaro
927 listings starting at $12,498
Used Toyota Camry
90 Great Deals out of 2,220 listings starting at $1,900
Used Nissan Altima
102 Great Deals out of 1,261 listings starting at $2,200
Used Ford Taurus
18 Great Deals out of 310 listings starting at $2,100

Used Cars For Sale

2017 Buick Regal For Sale
111 listings starting at $22,395
2016 Buick Regal For Sale
28 listings starting at $18,595
2015 Buick Regal For Sale
14 listings starting at $18,988
2014 Buick Regal For Sale
13 listings starting at $15,990
2013 Buick Regal For Sale
12 listings starting at $14,900

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.