[ramzsys]

Originally Posted by a4anurag

Damn Engineers!

No, not the engineers. It is the management side who are to be blamed.

[gauravdgr8]

Surely a very informative thread.

I remeber the time when M800 only had the normal temp gauge. It was the summer of 1994 and we were driving from Delhi to Nagpur. Somewhere in Shivpuri the car temp gauge went upto 70% and the Air con started tripping every other minute.

However nowadays, modern cars have the buzzer which comes up as the temperature goes up for any reason.

[SS-Traveller]

If your car is not accelerating, or responding more sluggishly to throttle inputs than usual, please glance at the temperature meter to see if overheating is occurring.

Has your car overheated and lost coolant in the mountains?

It is very tempting to collect water from a waterfall or stream nearby, and fill up your radiator with it. However, do remember that the water from a mountain stream is freezing cold, and some of it spilled onto your hot engine block can give a metallurgist a cardiac arrest (and you the bill for a new engine block). Please add such extremely cold water very very slowly and carefully into the radiator/coolant bottle with your engine running, and things should not come to such a pass as a cracked block.

[GTO]

Originally Posted by infotech58

Would you shed some light on why it is important to start the engine before start filling the radiator and how not doing so may end up in cracked engine block?

Cold water meeting hot engine can have the block crack up. You'll fill up, start the engine, the thermostat will suddenly open and a flow of fresh cold water will meet the engine. This way, there's lesser temperature difference between cool water & burning hot engine, the water pump is running to maintain circulation and it might also prevent / remove air bubbles.

Originally Posted by a4anurag

During cold starts, YES I feel the need of the gauge to know the state of the engine.

Related Thread

Originally Posted by SS-Traveller

If your car is not accelerating, or responding more sluggishly to throttle inputs than usual, please glance at the temperature meter to see if overheating is occurring.

Also noticed my Vtec knocking when the cooling fan was shot.

[silverado]

Most of times people do not realise when car gets in overheating mode unless it starts steaming.

Modern cars have electronic indications which should not be easily missed.
I believe car manufacturers should also have a sound alarm to indicate overheating.

I have faced it first hand when i was ripping my uncles M800 5 speed ( My daily drive was a padmini back then ), it was so much fun untill i realised i had to downshift more often , and then finally i noticed traces of steam.

After resting the car i managed to get it till my mech.

It gave a distinct sound in such a scenario, and the reason was faulty thermostat.

My padmini also overheated once, and all was well once the radiator was flushed.

There is a Radiator specialist opp chitra cinema in dadar east.( Near Francis Bullet shop ), charged 300rs, radiator never gave trouble after that.

The Sumo taxi in which we were travelling ( Manali-Leh ) also overheated due to broken radiator fan, and the one big mistake the driver did was open the hot radiator cap, it just shooted up like a missile, and everyone around was lucky.

Hence DO NOT OPEN RADIATOR CAP in such a scenario, since its a natural tendency to immediately pour water/coolant in radiator in such a scenario.

[SS-Traveller]

Originally Posted by GTO

Also noticed my Vtec knocking when the cooling fan was shot.

Newer gen petrols with knock sensors may not show knocking. Diesels won't.

Originally Posted by silverado

I believe car manufacturers should also have a sound alarm to indicate overheating..

The Scorpio VLX has it - audible (voice) warning to indicate overheating and low oil pressure.

[sridhar-v]

Over the last few months had 2 cases of overheating-

First on my Santro before Diwali. I had got the engine serviced, and the coolant changed. ( I do that along with brake fliud after 3-4 years!!). Next day I tried out the a/c but did not get cooling so went straight to the service centre. The overflow tank was full, but it was later diagnosed that the radiator was empty in the top part & hence the a/c temperature switch (measures engine temp) had tripped & was not allowing the a/c relay to operate. The possible reasons for low coolant were improper coolant filling or radiator cap malfunction. Topped up the coolant & replaced the cap.
The engine temperature warning light had not come on at any point.

Second was on the Ford Fusion. Was in heavy traffic & asked driver to switch on a/c. Did not get any cooling so assumed the compressor had developed a fault. Within 5 minutes got steam boiling out of the bonnet. Found out that the fan (electric) had packed up. Got it replaced & everything is now ok. In this case also the engine temperature warning light did not come on.

After discussions with the mechanics I have come to the following conclusion:-

The air conditioner is a good early warning indicator of low coolant levels. If it suddenly cuts off or stops cooling - check your coolant levels first. Even if the overflow bottle is full check the actual radiator. Do this by sticking ur fingers thru the grill(take necessary precautions to see that u are not in the fan area & preferably when the engine is shut down & switch in off position. Beware of self running electric fans!!). If the uppermost areas of the radiator are cold/ambient temperature then there is an issue with the coolant levels. And this is the reason why the a/c shuts down. When the coolant has been properly topped up & engine brought to temperature shut down & repeat the test. You will feel the "Chatka" of the hot coolant.

[Jeroen]

Originally Posted by sridhar-v

-

The air conditioner is a good early warning indicator of low coolant levels. If it suddenly cuts off or stops cooling - check your coolant levels first. Even if the overflow bottle is full check the actual radiator. Do this by sticking ur fingers thru the grill(take necessary precautions to see that u are not in the fan area & preferably when the engine is shut down & switch in off position. Beware of self running electric fans!!). If the uppermost areas of the radiator are cold/ambient temperature then there is an issue with the coolant levels. And this is the reason why the a/c shuts down. When the coolant has been properly topped up & engine brought to temperature shut down & repeat the test. You will feel the "Chatka" of the hot coolant.

How does that work then?

As far as I'm aware there is no connection between the coolant and the AC system at all? However, the compressor can sometimes be driven by the same belt as the water pump. If that belt snaps you have no circulation of coolant and the AC stops immediately. And if you continue driving your engine will overheat.

The only ambient temperature that plays a role with the AC is low ambient air temperature. Usually anything lower than 4o C and the AC will automatically be locked and won't work to prevent freezing.

Maybe some cars have a AC cut off based on high temperature of coolant to shed load on the engine? I'm not aware, but could be.

The condenser does rely on having some airflow across it, so if the fan packs up (electrical or belt driven) you might experience less cooling capacity, but I doubt it will stop working all together.

Just one more practical pointer when you refill the radiator. As pointed out always keep the engine running. Also open the heating controls to full heat. That ensures that you get rid of any air that might have been trapped in the heating core and the various heater valves. On some cars you have to de-air the cooling system as well. Check if you see any little bleed valves on the highest points of the various engine bits. Or better yet, check the (workshop) manual.

Jeroen

[SS-Traveller]

Originally Posted by Jeroen

As far as I'm aware there is no connection between the coolant and the AC system at all?

Yes there is. All (or almost all) cars have a little device that cuts off the AC compressor as soon as the temperature climbs above a certain preset - say, 95*C. Even the good old M-800DX had it (but aftermarket AC fitters never put that device in, and hence the disrepute of the M-800 as a car that overheated if AC was used).

[psvinay]

Question from a layman: Can't the ECU of modern cars detect the overheating and cut-off the fuel in case of overheating? These days every car has ECU, so is this really a data to watch for? I drive a SX4, I know it has a ECU and drive-by-wire system. Should I also be watching for a probable engine overheat situation?

[sridhar-v]

Originally Posted by Jeroen

How does that work then?

As far as I'm aware there is no connection between the coolant and the AC system at all? However, the compressor can sometimes be driven by the same belt as the water pump. If that belt snaps you have no circulation of coolant and the AC stops immediately. And if you continue driving your engine will overheat.

The only ambient temperature that plays a role with the AC is low ambient air temperature. Usually anything lower than 4o C and the AC will automatically be locked and won't work to prevent freezing.

Maybe some cars have a AC cut off based on high temperature of coolant to shed load on the engine? I'm not aware, but could be.

The condenser does rely on having some airflow across it, so if the fan packs up (electrical or belt driven) you might experience less cooling capacity, but I doubt it will stop working all together.

Jeroen

Even I used to assume that the a/c does not have a sensor for coolant temperature. But it turns out that OE fitted systems do have some sensor connected to the cooling system. The SA @ Hyundai workshop was not aware of this but the mechanic (who operates as a freelancer attached to the service station) was emphatic that the sensor also checks for presense of coolant & shuts down the a/c system when coolant levels in the radiator drop. This happens much before the coolant starts to boil over due to overheating. The Santro did not overheat for the simple reason that I took it to them for checking the a/c. The mechanic immediately touched the top area of the radiator fins & declared low coolant!!

Same thing seems to have happened to the Fusion. Due to the fan failure the coolant must have been evaporating from the overflow tank first & then top of the radiator. And that was why the a/c would not start.. When we got stuck in traffic the engine boiled over. I remember looking over the drivers shoulders at the instrument panel a few times during the drive & the temperature warning light did not come on. Later on the Ford mechanic also confirmed that the warning light will not come on in such cases.

Looks like the temperature sensor is located in the top chamber of the radiator & when the coolant level drops it is only sensing the ambient air temperature. Need to check out my theory during the next servicing.

[Jeroen]

Originally Posted by SS-Traveller

Yes there is. All (or almost all) cars have a little device that cuts off the AC compressor as soon as the temperature climbs above a certain preset - say, 95*C. Even the good old M-800DX had it (but aftermarket AC fitters never put that device in, and hence the disrepute of the M-800 as a car that overheated if AC was used).

Thanks, I didn't know that.

Jeroen

Originally Posted by psvinay

Question from a layman: Can't the ECU of modern cars detect the overheating and cut-off the fuel in case of overheating? These days every car has ECU, so is this really a data to watch for? I drive a SX4, I know it has a ECU and drive-by-wire system. Should I also be watching for a probable engine overheat situation?

Yes, in theory it can be made to do that, plenty of sensors, but you don't want the engine being shut down automatically. That could be dangerous. So the thinking is that its better to ruin the engine, but leave it running so you can get your car stopped in a safe place, rather than it coasting to a halt with the engine automatically being cut off by the ECU.

Its the same with oil pressure. Low or no oil pressure won't shut down your car and it's even more disastrous than an engine overheat. Same principle, as long as its running, it can get you to safety in a controlled way.

Although it does happen I would think that overheating an engine on an modern, well maintained car these days is pretty rare. So I wouldn't worry about it at all if I were you.

Just keep watching for those warnings lights, or gauges if you have them!

Jeroen

[StrangeWizard]

This happened in Sept'12.

Had given my Spark for a regular service at the a.s.s.
Took her after she was ready. Drove for a km and realised the AC wasn't cooling properly at level 1. Switched it to level 2.
The temperature gauge kept rising and went above the half mark.
It kept rising very slowly and went upto the red mark. I quickly stopped on the side with the hazard lights on.
Opened the bonnet to check the coolant level in that white transparent box. It was OK.

Called up the a.s.s and they called up the breakdown assistance guy who was in Andheri and i was at Goregaon link road.
It was 8pm and i didn't want to drive 3-4 kms back to the a.s.s.

He took about an hour to come.
He started checking and solved the problem in 10 mins flat! The ac blower fuse had gone kaput. I didn't know how to check the fuses for any problem. The guy connected some meter i think.

I remember once we had gone to Lonavla in our 800 around 13-14 years back when my dad opened the car's bonnet and some green liquid just blasted out like a big fountain. i don't remember what exactly it was but i was scared as hell.

[honeybee]

The posts cover pretty much everything needed to be covered. However a note of caution: Most people will have their engine bay dirty enough to prevent seeing the coolant level clearly in the coolant reservoir. People may want to clean up the outside of the reservoir to see the coolant level, but it's advised that this be avoided till the engine cools down considerably. Accessing the coolant reservoir would inadvertantly bring your hand in contact with the radiator and you may get some burns.

Never ever throw water on the radiator/engine bay when it's hot. At the most if you can get it cooled down enough to open the radiator cap, let it blow off the steam completely.

Common sense advise of DON'T PANIC should apply in this case too. If you notice the engine overheating, instead of switching the engine off completely take your foot off the accelerator and use the momentum to steer your car clear of the traffic. As long as you don't use the accelerator you should be able to safely come to a stop out of harm's way (your harm or others' harm). Even after parking the car safely, leave the engine running at its minimum RPMs. Switch it off only after the temp returns into the green/white zone.

Most important: I remember GTO had asked this in an earlier thread: What do you do with cars which don't have a temperature gauge? My Nano too doesn't have it, and so the only indication of an overheating engine would be a glowing/blinking light on the dash.

[R2D2]

Great thread especially for us motorists in a hot tropical country like India. This thread has covered nearly everything. My 2 pence as follows:

Though modern cars hardly need checkups under a hood it may be wise to do so especially before long trips out of town. You do not want a busted radiator or head whilst travelling thru rural areas.

it is worth mentioning is that most mechanics here tend to ignore the dilution ratio of coolant concentrate with water. Please stick to manufacturer recommendations. Normally a 50:50 ratio is recommended with the ratio increasing to 70:30 in cold mountain climes.

As with so many things in the auto maintenance world more coolant concentrate is NOT better. Contrary to what most people believe, it is water, not coolant, that is the heat exchange medium. So check your manual for the dilution ratio.

Also, some coolants have chemicals/additives that are must haves for certain metals or alloys in the engine assembly they are primarily to prevent corrosion, deposits and lubrication. I would strongly suggest using the OEM coolant. Many come premixed so there's no worry about using hard water.

Modern OEM coolants have an extended service life up to 100k miles/160K kms. But be sure to change the coolant (as with other fluids) at recommended intervals.

If you do mix plain water in the coolant in an emergency, get the system flushed and refill with distilled water + recommended coolant concentrate in the correct ratio or use premixed OEM coolant.