Hello,
I have a 200 Mazda Protege ES 1.8L Automatic.
I stopped using it for almost a year and when I used it again, I noticed (using a scanner) that the temperature would go up while driving and down while idling. (No codes btw)
I took it to the highway and when it was about to reach 220°F, I turned on the heat full blast. It went down to 208°F and stayed there. (So the heater works)
Both fans work, AC works, coolant is at the right level and doesn't move.
What could be causing this?
Reporting back. Replaced the radiator with a Denso one, and the thermostat with an Aisin one, new gaskets, cleaned everything, back flushed the coolant inside the engine, and put everything together.
It doesn't overheat anymore. Works perfectly. Just after finishing that I did a hardcore test and went on a 300 miles trip while watching the temperature with an OBD2 scanner. It stayed between 187°F and 196°F. Amazing temps for this car.
Thanks for everything Chuck!
@dave5000 Great, thanks for letting us know!
Clogged radiator, collapsing lower radiator hose, deteriorated water pump impeller.
@chucktobias Thanks, my theory was the clogged radiator.
Hoses are aftermarket and not that old.
Head Gasket was done recently with timing belt, water pump, tensioner, etc.
How can I test the radiator?
@dave5000 Check the radiator for cold spots.
@dave5000 A stuck thermostat can also cause overheating.
@chucktobias about the stuck thermostat, will it also cause that only at high speed? With heat working fine?
@dave5000 I could see it happening if it only opens part way and coolant flow is restricted at high speed. How old is the thermostat?
@chucktobias The thermostat should be around 4 or 5 years old. I bought OEM. I could replace it anyway if necessary.
Btw, I check the radiator,
Around top driver's side corner was 170°F
Middle top was 234°F to 212°F
Top passenger's side corner was 220°F to 202°F
Bottom passenger's side was 180°F
All those temps were taken with AC off and around the fan shrouds.
Engine temperature according to the scanner and thermometer never went over 208°F
Btw, I don't know if it matters but the radiator also cools the transmission.
@dave5000 Any cool spots on the face of the radiator indicating a clog?
Either your radiator cannot get rid of enough heat with the engine under load or you don't have enough coolant flow at speed.
@chucktobias thanks for your time Chuck! I ordered a radiator and a thermostat. We'll see if it gets better!
@dave5000 I would have done a little more testing before buying parts. Although the radiator is certainly a suspect, especially if original, there's still a chance it could be something else like a water pump, collapsing lower radiator hose, or the worst case of course would be a blown head gasket. Let us know how you make out.
@chucktobias The radiator is a Denso I installed about 3 to 4 years ago. I replaced the original one because it leaked and my engine overheated. I installed the new one, thermostat, and hoses. But after driving a while, the car started pushing water to the reservoir and got hot. The head gasket was partially blown and combustion gases were passing to the cooling system but not coolant in the oil. I tried bars head gasket sealer, didn't work. I did head gasket, timing belt with pump and tensioners, refinished the head, etc. When I open the engine, there were particles of the sealer partially blocking the coolant passages. I can only imagine that might also happened to the radiator.
That's why I didn't hesitate to get new parts.
What do you think?
I tried bars head gasket sealer, didn't work.
That's the expected outcome with "mechanic in a can" products. They frequently do not work.
When I open the engine, there were particles of the sealer partially blocking the coolant passages.
Also the expected outcome.
What do you think?
It confirms what most of us say about those kind of "sealer" products, use them only if the alternative is the junkyard. At that point there's nothing to lose. However if the plan is to keep the vehicle as long as possible a proper repair is required.
In the situation you describe ordering the new parts sounds like a good idea. You should also give the engine and heater core a good flushing out and pray that the stuff has not solidified in and blocked the engine's internal cooling passages.
@chucktobias yes! I'll do that and report back, I'll probably install everything tomorrow! Thanks again for your time!