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 214 nationwide Regal listings starting at $8,995.

Postal Code:

Buick Regal Experts

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

Related Models For Sale

Used Chevrolet Malibu
66 Great Deals out of 1,826 listings starting at $2,495
Used Chevrolet Impala
159 Great Deals out of 1,103 listings starting at $2,950
Used Honda Accord
61 Great Deals out of 1,276 listings starting at $1,215
Used Chevrolet Camaro
1,083 listings starting at $12,995
Used Ford Mustang
1,040 listings starting at $3,900
Used Cadillac CTS
16 Great Deals out of 345 listings starting at $3,450
Used Toyota Camry
37 Great Deals out of 1,947 listings starting at $1,995
Used Nissan Maxima
20 Great Deals out of 409 listings starting at $1,995

Used Cars For Sale

2017 Buick Regal For Sale
96 listings starting at $21,888
2016 Buick Regal For Sale
29 listings starting at $18,990
2015 Buick Regal For Sale
17 listings starting at $15,800
2014 Buick Regal For Sale
8 listings starting at $14,001
2013 Buick Regal For Sale
9 listings starting at $15,498

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.