Car overheating issue?

[nigel89]

Dear all nice to meet you all this is my first post,i have 2005 Mazda 3 manual car...yesterday when i was coming home from a small trip i heard my fans running faster than normal...so i checked the gauges and the heat was near 3/4 to "H"..I suddenly turned off the car and let it cool down....while cooling down I checked the engine there was no leak or boiling coolant....I didn't feel abnormal hot near the engine....anyway after starting again i revved the car for a bit till 6000rpm, after that car was in normal temp till i get home....so today morning i started the car.. again the temp slowly passed ahead the normal temp..so i revved again bit hard then it came back to normal temp...what could be this issue??

Note:Only thing recently did was last week i replaced the coolant reservoir with a new one(it had a small leak)..I tried burping the system to get any air out but couldn't see any..

[TheMAN]

possible you may never had cleared the system of all air, or possibly a bad thermostat
if you poured coolant into the tank quickly, air pockets result.... any time you refill the cooling system, it must be done slowly to reduce this risk

[nigel89]

possible you may never had cleared the system of all air, or possibly a bad thermostat
if you poured coolant into the tank quickly, air pockets result.... any time you refill the cooling system, it must be done slowly to reduce this risk

HI MAN I just replaced the thermostat with a OEM....But on my way back home the issue came again so i revved the engine then again it came back to normal.. after that till i get home temp was fine....how can i get this air out if there's any,,

[XTOTHEL]

HI MAN I just replaced the thermostat with a OEM....But on my way back home the issue came again so i revved the engine then again it came back to normal.. after that till i get home temp was fine....how can i get this air out if there's any,,

The air bubbles, if there is any, should sort themselves out after driving a bit. Just check your coolant often and keep it topped up.

[nigel89]

The air bubbles, if there is any, should sort themselves out after driving a bit. Just check your coolant often and keep it topped up.


HI xtothel now its been 3 days when the issue comes temp gauge climb a bit above normal gradually and come down back to normal and so forth,so then i rev the engine to about 6000 rpm,then after than i can drive the car for hours without any problems...apart from a air bubble could this be due to a bad water bump,I'm afraid...car doesn't make any abnormal sounds,fans just works fine,coolant doesn't drop,heater works fine....If it was a air bubble why i can drive for hours without any problems?:(

[XTOTHEL]

HI xtothel now its been 3 days when the issue comes temp gauge climb a bit above normal gradually and come down back to normal and so forth,so then i rev the engine to about 6000 rpm,then after than i can drive the car for hours without any problems...apart from a air bubble could this be due to a bad water bump,I'm afraid...car doesn't make any abnormal sounds,fans just works fine,coolant doesn't drop,heater works fine....If it was a air bubble why i can drive for hours without any problems?:(

Do you have anything that can monitor the temperature the coolant temp?

[Noisy Crow]

If it was a air bubble why i can drive for hours without any problems?:(

Maybe sticking thermostat? I know it's new, but you are right, seems weird the problem is so intermittent..... which means you need to look for an intermittent root cause, such as a 'stat that needs to open and close (or damp weather etc for electrical). I can't recall where the thermostat is located... but I am thnking if it is accessible: next time the temperature starts to climb try rapping on the 'stat housing with a wrench to see if you can get it to pop open (assumng it is stuck closed). If it is stuck closed I am thinking that the upper rad hose will be warm, but won't be hot like it should be when coolant is circulating though the rad.

[m_bisson]

Do you get hot air from the vents?

[nigel89]

Do you get hot air from the vents?

Yes it blows hot air...and it's gradually becoming more hotter as rev the engine...

[m_bisson]

Probably the thermostat. If the vent air keeps getting hotter then the coolant IS circulating in the engine, but I seems like the thermostat isn't letting it past.

[nigel89]

Probably the thermostat. If the vent air keeps getting hotter then the coolant IS circulating in the engine, but I seems like the thermostat isn't letting it past.

Hi bisson i just replaced my thermostat with an genuine one 3days ago...but the problem came once again while i was coming back home so i revved the engine a bit and gauge came to normal...after that car can idle in traffic for hours without heating up fans are working fine...i don't know what the hell is wrong..

[m_bisson]

Yeah I read the thread. I'm saying it's the new thermostat causing the problem. It makes the most sense, given what you're describing.

Rev the engine to the point where it gets extra hot and the water pump is really pumping, and that may open the stuck thermostat.

[XTOTHEL]

Where so you live? If around KW, I have something you can monitor your coolant temp with.

Also can someone explain this "sticking" thermostat thing? Why would a thermostat have moving parts?

[m_bisson]

There's a rubber gasket on it, which could cause the sticking. It might have a bit of a lip or some defect that's holding things together.

[r4BBiT]

Where so you live? If around KW, I have something you can monitor your coolant temp with.

Also can someone explain this "sticking" thermostat thing? Why would a thermostat have moving parts?

Thermostat opens and closes so that's why it has moving parts or are you asking something else? :D

[stock3]

Does the radiator fan come on when the temp climbs above normal? If you don't know, next time this happens, instead of revving the engine, turn on the AC. This turns on the radiator fan and if the temp goes down that way, you may have a faulty coolant temp sensor. Or if the fans don't come on at all, you need to look at that.

[Flagrum_3]

Does the radiator fan come on when the temp climbs above normal? If you don't know, next time this happens, instead of revving the engine, turn on the AC. This turns on the radiator fan and if the temp goes down that way, you may have a faulty coolant temp sensor. Or if the fans don't come on at all, you need to look at that.

+1

[TheMAN]

remove the reservoir cap and warm the engine up.... then hold the RPMs at 2000 for around 10 minutes or until the fan turns on... that should get rid of most of the air... DO NOT turn on the heater or A/C during that time
top up coolant as necessary