Honda city 2012 overheating problem

[pwuser152119181238]

Dear friends
I am facing the issue of over heating in my car, honda city 2012 MT.
Got the car checked by live scanner. The radiator fans work properly and turn on off at specified temp, the fan would turn on at 106C.
No visible leakage has been detected, however, coolant level drops significantly. Car hardly moves 15kms when it shows overheating issue, blinking red light.
I must say here that we are now topping up with water only and trying to figure out where the problem lies. Prior to heat up issue, it had Honda coolant in it. The car is with me for more than 3 years and I have never seen its coolant level dropping. My own research shows following culprits
1. Leakage from radiator cap
2. Leakage from water body/pump
3. Leakage from main radiator body
4. Blown gasket
As I already said, we couldn't find any visible leakage. How can I be sure if radiator or water is leaking? I pray the culprit is not the gasket. I would certainly be difficult thing to be repaired.
Advice from members is requested please.

[pwuser152119181238]

Anyone there

[smsaz90]

There are many other signs of weak or blown gasket that can be checked, look out for oil water mixing physical examination after removing oil cap or oil's condition after drain can give little idea. Check all coolant pipes including the ones which takes coolant to the throttle lastly check for steam leaking sounds from the engine bay once the red line get on after switching off the car.

[zakiuddin]

one of the basic checks that you can do is to remove the thermostat and put it in the boiling water and see if it opens up... a stuck closed thermostat would exhibit similar symptoms...
next thing you can make sure is that your water pump is working fine.. You can do this by putting a transparent pipe piece somewhere between the coolant lines and see if coolant moves when the car warms up... or if you don't wanna do that, just try measuring/sensing temperature of inlet and return radiator lines to see if hot water enters from top of radiator and leaves at bottom

[shakeel9045]

In all cases run engine in idle state with coolant filled & carton sheet placed underneath car, take note of wetness on carton if any. As per my experience if leakage is not detected then it means that it dries up quickly after leakage or falls on plastic sheet below (if still there is one) which may/may not show with flashlight. radiator body leakage might very likely at the top & might be a very minute crack line due to which it goes unnoticed so you will need a very close inspection of the radiator body. If it were the gasket then bubbles appear in the radiator as if coolant is boiling, run engine in idle state with radiator cap open & observe. if it were radiator cap seal then you'll see coolant expulsion from radiator cap due to pressure leakage & usually the underside of bonnet gets wet & dries quickly, if waterbody/pump issue then you'll still see coolant drops below. Check the hose that connects engine to radiator also to rule out this possibility.

[pwuser152119181238]

What do you mean by bubbles? Continuous bubbles or random counts of two three bubbles? And what are signs of bad water pump?

[shakeel9045]

Imagine air trying to pass through water, that is what happens here and bubbles are formed. Initially when the problem starts you'll see about 2-3 bubbles every few seconds & then it'll be continuous as it gets major....imagine water boiling such is the intensity of bubbles. Two major signs of bad water pump its pulley starts to make noise & water leakage from waterpump (generally obvious when you see water dripping from near close proximity to engine).

[pwuser152119181238]

So you mean that if we notice bubbles then it is sign of bad water pump? Or the bubbles represent something else?

[shakeel9045]

Bubbles (air exiting) from radiator indicates gasket issue.

[pwuser152119181238]

I have just changed the oil. No sign of water mixing was found. Before oil change, it gave red light, I topped the radiator with water and I went for oil change the next day from Honda service center. If the gasket is leak, shouldn't the oil water mix or I am wrong? Just wanna know

[shakeel9045]

I didnt mention that your car's gasket has leaked, I have pointed the symptom (because you mentioned it might be a culprit so its for you to check). In my experience the oil/water mix may not always show in the radiator or it might be very thin film to notice, it depends on the severity of the issue but if you see bubbles rising then there is air leakage (99% of times its this issue) so when you see bubbles consider it a cause of serious concern & visit the workshop soon as you can. I have also pointed out other areas that might be causing the coolant to dissipate, you have the car & you are the best judge.

[pwuser152119181238]

I have tried to look for any bubbles while the engine was idle. I couldn't find a single bubble. Moreover, I have changed the radiator cap and installed a new one with 1.1bar rating. Additionally, mechanic has also checked the thermostat and fans. Fans switch on switch off behavior is fine.
What we know about the issue so far
1. When overheated, the radiator passes water/steam back to reservoir bottle and we could hear sound of steam bubbling through bottle. It eventually emerges out of reservoir bottle cap
2. The engine overheats after driving for around 15kms
3. As the water goes out from reservoir bottle, water level drops. No other visible leakage could be found.
As we have refilled it for more than 10 times and each time it gets 300/400 ml water, the coolant color has changed to colorless, looks like water now. Is it also a reason that the car is over heating?
We removed and re-fixed all inlet and outlet pipes to ensure there isn't any leakage from pipes or connections.
My mechanic now suggested me to get checked three sensors (I don't know which sensors he is talking about)
@shakeel9045
@hash4u
@xulfiqar
Please guide

[Xulfiqar]

When overheated, the radiator passes water/steam back to reservoir bottle and we could hear sound of steam bubbling through bottle. It eventually emerges out of reservoir bottle cap

only liquid should be sent to the expansion tank - if you are seeing steam or vapour bubbling in the expansion bottle, you have a compromised cooling system. - probably a corroded cylinder block, loose head or bad headgasket or all of these.

[pwuser152119181238]

I can't say for certain if it is steam or liquid, but one thing is certain that water over flows from reservoir tank. I don't know much about car maintenance, i just visit honda center and do whatever they say. I haven't seen them yet for this problem. A trusted mechanic is doing this stuff. But before he proceeds for any thing, I try to look at pakwheels and try to understand what are consequences of his step.

[pwuser152119181238]

Dear all
Checked the running car with live obd scanner. When the red light came, the coolant temp showed a temp of 90C where as the engine temp was 118. At this point, the fans were off. Fans only kick in when coolant temp goes 105C. At 118 the car showing over heat light.
My question is why is there a lot of difference between engine temp sensor and that of coolant temp sensor? Is it normal or any of the sensor is faulty?
@Xulfiqar
@shakeel9045

[pwuser152119181238]

This pic shows the status at idle

This pic shows status when driving, the car has over heated, but the fans didn't come. The other sensor showed the temp as 76 while the other sensor shows temp as 118.

PS: both pics were taken when the thermostat was removed

[roony]

I think sensor 2 is on the radiator, fans use that as a ref for kicking in.

Maybe your thermostat is stuck in a closed position.

[pwuser152119181238]

We have removed the thermostat as well, means free of thermostat.
Changed both sensor1 and sensor2. Problem persists. Temp at sensor1 reads as 118 and that of sensor2 reads as 76. Fans come in once temp of sensor2 is above 95.
We have done following things
1. Changed both sensors
2. Removed thermostat to see its blockage
3. Changed the rad cap
4..Changed any pipe which we suspected could be damaged and could cause coolant leakage

Any further advise on what to do?

[pwuser152119181238]

The car is running on tap water as coolant has drained due to leakage. We are not purposefully adding coolant. Coolant would be added once we make sure that all leakages have been blocked.
Can tap water be a reason of over heating?
Mechanic says there isn't a chance of gasket leakage. We don't see bubbles or oil water mixing.

[Xulfiqar]

Seems like a non working water pump