[Ray32825]

Originally Posted by Ricci

To my knowledge, engine temperature is measured by measuring coolant temperature (engine temperature itself is not measured, and that varies depending on where you measure) , there is no other temperature measurement as far engine is concerned - maybe apart from oil temperature which is not always displayed. Some amount of convection flow would be there, but if the coolant pump is malfunctioning, yes the coolant will not circulate as normal.

Let's see what ASC diagnosis is.

Damn good Ricci! You are spot on as far as the temperatures are concerned. The coolant temperature is only a representation of the engine temperature and is not the most accurate one, in fact, the oil temperature is a more accurate representation of the engine temperature. You are absolutely right, this is not often provided except in some high-end cars, mostly German vehicles.

As regards the coolant flow, again you are right about the temperature represented on the gauge. It is usually measured on the head/thermostat housing etc. The thermostat when closed prevents the coolant from circulating back into the radiator, on most engines there is a bypass that allows the coolant to circulate through the engine until the operating temperature is reached. This causes the scenario where the coolant is hot and sometimes even boiling in the engine but is cold in the radiator. There is no flow or circulation in the system due to the closed thermostat.
The only way the coolant in the radiator can even get slightly warm is through conduction or through the miniscule amount that flows past the pinhole in the thermostat valve which is basically there to bleed air and not for coolant to flow through.
Usually what happens in this scenario is that the radiator fan is on full speed (2 speed system) and this dissipates any little heat that may be present in the radiator. Therefore, to the average Joe, it seems odd that the coolant/radiator/hoses are warm to the touch where as the engine is indicating overheating. The fans often manage to keep the pressure and temperature in the radiator down and so there is no overflow situation as well.
The best way to deal with the situation on the road is to use the heater as you all know, just point the vents towards the windows to avoid getting cooked. Also, if the electric fans are not being commanded on for some reason, an easy way to do this is to unhook the coolant temperature sensor. This will cause the fans to come on even if the engine is not running and may help cool things down a bit.

[jaspal singh]

Originally Posted by Ray32825

Damn good Ricci! You are spot on as far as the temperatures are concerned. The coolant temperature is only a representation of the engine temperature and is not the most accurate one, in fact, the oil temperature is a more accurate representation of the engine temperature. You are absolutely right, this is not often provided except in some high-end cars, mostly German vehicles.

Talking about oil temperature, during test drive the OBD scanner was showing Engine Oil Temp between 118-120 C when the Water Temperature was between 108-110 C. I did point this to the service advisor who said they monitor only water temp in overheating cases! Can we draw any inference from this situation as even a layman would consider engine oil temp at 120 C to be unusual.

Have given the vehicle to Capital Hyundai Sec 2-Noida workshop today, the workshop head has requested 2-3 days to rectify. anyways will visit the workshop tomm to monitor the repairs.

[Ray32825]

Jaspal, don't worry about the oil temperature it has to be at a minimum of 105°C to evaporate any moisture in the system. If the oil temperature is consistently below a hundred degrees it will lead to water combining with sulfur (both byproducts of combustion) to give sulfuric acid which will corrode bearings etc.
All that has nothing to do with your system/problem, that was merely going over some theory. The other part about the thermostat is what pertains to you. Could you PM me your phone number so I can call you - it's a lot easier than typing.

[jaspal singh]

Originally Posted by Ray32825

Well done Jaspal, sounds like your diagnostic skills are better than the mechanic's. It looks like they lied to you about cleaning the thermostat - probably did not even open the system.
If I was you, I would have them drain the cooling system installed a new thermostat and run a radiator cleaner/flush through the system. Drain and refill once more with fresh coolant.
Also check with the service advisor to see if there is a procedure for bleeding/burping the system to get rid of any air and make sure it is performed.
If you have any questions, or need any help with anything, don't hesitate to PM me.

Hi Ray,

It seems my nightmare has just begun. Service advisor called me today at 6pm stating the car is ready for delivery. reached there at 6:30 and i was told that the radiator fins were choked with Slush/debris and they have cleaned the radiator in a chemical. They had removed the condensor etc to carry out the job. They even showed me photograph of the clogged radiator. as per them they had carried out a 30 km testdrive and the water temp never crossed 85 C mark. I was assured that the problem has been rectified.

But i have just returned from south extension market which is a few kms from here and on the return trip, the problem has resurfaced I have taken the pics . Please check the KM readings. On the invoice given today its 40544 while the pic shows 40631.so even with ambient temp at 32C car has overheated. As noticed earlier also i and my friend opened the bonnet, only to find the fan working normally and air temp also seemed to be normal.

Please suggest what should i do now, as the car's warranty is expiring on 7-July and i'm fed up with these repeated visits to workshop, this being the third one.

Also notice the dramatic decrease in Fuel needle level for a distance of only 13 km between two Pics.

[Ray32825]

Dear Jaspal, as I mentioned to you in my PM, I guess you are at the mercy of the dealership as your car is under warranty. I was wondering about the condition of the coolant but considering this was a fairly new car with only 40,000 km on it I assumed it to be in tiptop condition.

Okay, let's take this step-by-step. First of all let's verify that the engine is actually overheating. You mentioned that the fans were coming on and I think you could feel the heat being dissipated from the radiator, am I correct? We need to know if the temperature of the coolant in the system is actually what the gauge is showing us.
I am assuming that your car was running at around 90°C prior to the overheating problem. Now let's see if it is actually overheating under the hood. The best way to do this is with a temperature gun, do you have access to one? This will enable us to read the temperature on the radiator, on the thermostat housing, on the intake and outlet hoses etc. This should correspond with the temperatures depicted on the gauge. If this is not the case then it seems we have a problem with your instrument cluster gauges - which could explain the inaccurate readings on the fuel gauge is well.

[sandeepmohan]

Originally Posted by jaspal singh

It seems my nightmare has just begun.

This might be a little extreme to do. I'd give it a shot though. With the hood open, no air conditioning running, crank up the engine and watch if the coolant is boiling and if its trying to push its way out of the expansion tank. This will happen only once the temperature goes high. You can observe for small traces of steam coming out of the coolant expansion tank cap. If there is steam and coolant boiling, then you have a very serious problem of the coolant passages that are blocked around the engine block. An air lock in the system is also possible. You can also check if the radiator fan is coming on in time. It should once temperature increases above normal. There is no risk of seizing the block. The moment you see coolant boiling or steam, its time to turn off the engine.

I will try the above with the engine already at optimum operating temperature. It might take took long from a cold start. Do not stand in front of the car while doing this. Keep some distance from the engine bay and observe.

[SS-Traveller]

Originally Posted by jaspal singh

...please suggest what should i do next and possible cause of the problem.

Originally Posted by jaspal singh

Fan is working normally and kicks in immediately with AC.

Originally Posted by jaspal singh

Talking about oil temperature, during test drive the OBD scanner was showing Engine Oil Temp between 118-120 C when the Water Temperature was between 108-110 C.

Ask your service centre to carry out the following checks:
1. Remove both cooling fans and check them physically to see if they run smoothly or appear to be jammed. Replace fan(s) if jammed;
2. Open & check the electrical connectors for the fans for looseness / burn marks. Replace / tighten as required;
3. Check with OBD scanner at what coolant temperatures the cooling fan (not the AC fan) trips on and off;
4. Flush the radiator and replace with fresh coolant;
5. Change engine oil.

If your current ASC is unwilling to do the job, you ought to take the car to Hyundai Motor Plaza, the company-owned service centre on Mathura Road. A complaint logged before warranty expires has to be attended to by the company as if the vehicle is still under warranty, even though at the time of resolution the last date of warranty cover may be over.

[jaspal singh]

If your current ASC is unwilling to do the job, you ought to take the car to Hyundai Motor Plaza, the company-owned service centre on Mathura Road. A complaint logged before warranty expires has to be attended to by the company as if the vehicle is still under warranty, even though at the time of resolution the last date of warranty cover may be over.

I have lodged a official complain through Hyundai's Customer care and they will pick my car tommorow. yesterday night i was stuck on DND flyway as temp needle touched 130 mark. Also this was the first time i saw leaking water below the car. What will happen if its a serious issue like blown head or cracked head?

[sandeepmohan]

Originally Posted by jaspal singh

as temp needle touched 130 mark. Also this was the first time i saw leaking water below the car. What will happen if its a serious issue like blown head or cracked head?

I suggest you stop as soon as the needle starts at the red zone. Why let it go all the way north.

I doubt if this is a blown or cracked head. You will have a lot of smoke (not steam) emitting from the engine block if this is the case.

To me it looks like coolant is being pushed out of the expansion tank. If there are no hose leaks, this is the only way it can escape. Look for source of the leak.

[Ray32825]

Jaspal, just curious, you mentioned the radiator being cleaned by the dealership but nothing about the thermostat. Also you indicated that when you and your friend opened the hood the fans were working and the temperatures seemed okay - could you feel the heat from the fan/fans as they were trying to cool the radiator? Coolant seems to have overflowed from the front of the car - that's good/normal with the system overheating.

Also, did you put the heater on with the blower on full, (vents pointing towards the windows), to bring down the temperature? If you had done this and the temperature had come down, this would have indicated the following:

1. That the water pump was working fine - coolant was circulating well
2. That you had enough coolant in the system - no air pockets
3. System had the ability to bring down the temperature - no cracked head etc.

In any case, as I mentioned to you earlier, it seems as though you are at the mercy of the dealership/manufacturer and hopefully you will be grandfathered in even if the problems persist after your warranty expires.

I'm assuming this is what the engine layout looks like in your car.

[jaspal singh]

Originally Posted by Ray32825

I'm assuming this is what the engine layout looks like in your car.

yes this is the same engine Rest we have already discussed over phone.

[jaspal singh]

Originally Posted by sandeepmohan

I doubt if this is a blown or cracked head. You will have a lot of smoke (not steam) emitting from the engine block if this is the case.

To me it looks like coolant is being pushed out of the expansion tank. If there are no hose leaks, this is the only way it can escape. Look for source of the leak.

Hi,

went to the workshop today evening and they have replaced the radiator and thermostat under warranty. The old radiator had a small hole at bottom right which was detected during high pressure testing.
A 30 kms test drive did not show any signs of overheating.

I just hope the problem doesn't re occur as they have assured me that they have managed to find the problem. Car would be delivered tomorrow after further testing and washing

Please share your opinion about this being the right diagnosis? Since i am wondering about the initial problem which resulted in overheating in cyclical way or only when the car moved slowly.

Regards,

[saket77]

Hope that the problem is sorted from the root now. I always doubted the thermostat, but as in the pictures, the radiator fins look quite choked by debris. At some points, they also look damaged. Do let us know if the problem is completely gone once you test the car in real world scenario. And you know what, you should be glad that the engine did not seize during all this time it was overheating.

[nik0502]

Hi Guys,

I have a problem here and need help from all of you. I recently purchased a Pre owned Maruti Esteem. The car has run 54 K on the ODO only on petrol (No CNG Added). Car is a 2005 Model. I understand everybody will have a doubt about the ODO reading but the previous owner has 4 cars and this was the least used one and the oldest one with other cars being i20 Diesel and a month old Honda city Diesel. And the guy seemed to be a genuine person.

Now the problem i am facing is last weekend i went for a 100 KMs drive. And after driving around 40 KMs i got stuck in stop and go traffic and suddenly the AC stopped cooling. I immediately looked at the temp gauge. It was little above the normal temp but was on a rising trend. I had no option but to drive as reaching destination was really important at that time. But i drove very cautiously and did not let the temp needle go above the normal temp. As it was all highway drive it was not a problem. I poured water in the raditor once after shutting the car down for more than 30 -35 min. As i did not know that i was supposed to pour water with engine running. Drove for another 50 KMs and drove the same way did not let the car overheat was monitoring the temp needle cautiously and poured water after leaving the car off for more than 45 min. This time a gentleman asked me to put water with engine running and i did the same. Took the car to my FNG the next day and we figured out that car was throwing the water out when overheated.
My mechanic suggested me to change the head gasket and face the head as we could see very small bubbles in the radiator. The car does not over heat on short drives say on a 10 KM drive. I consulted another workshop near my place. This guy suggested a radiator flushing. Went ahead with the suggestion. Did the radiator flushing at his place though i was not present when it was being done on the car. The guy also told me that there was a valve missing in the car and he has put it but the problem is still there though not as bad as it was before. The car used to take approx 800 ml water before but now its only 250 ml water which it takes on a 30 km drive.

I thought about getting the head gasket changed but read in the previous pages of this thread that the car would never drive the same again after that. Can some one help me in this situation. I have bought the car to keep it for few years.

nIk

[deep_bang]

Originally Posted by nik0502

Hi Guys,

The guy also told me that there was a valve missing in the car and he has put it but the problem is still there though not as bad as it was before. The car used to take approx 800 ml water before but now its only 250 ml water which it takes on a 30 km drive.

I thought about getting the head gasket changed but read in the previous pages of this thread that the car would never drive the same again after that. Can some one help me in this situation. I have bought the car to keep it for few years.

nIk

Ideally, the car should not lose water or coolant at all, Atleast not over a few days. Are you saying that after a 10 km drive the coolant level in the coolant reservoir is reduced by about 250ml? If that's the case I suspect that there is a leak somewhere in the whole pipeline - either the pipes connecting the coolant reservoir to the radiator, or the radiator itself.