[GTO]

This guide is intended for the regular joe (99% of motorists out there) who faces an overheating engine on the road. While it's best to immediately visit a service station in this situation, the following diagnostics & remedies should come handy if you are far away from help.

No matter how modern or reliable your car, overheating isn't an uncommon occurrence. Excessive heat can completely destroy your engine, hence it's important to take the right decisions when the temperature needle swings into the red.

Team-BHP lists below the most probable causes of engine overheating. The points are listed in order of occurrence (most frequent first). Do note that troubleshooting an overheating engine is far simpler in cars that are equipped with a temperature gauge. Some modern cars only have an “overheating” warning sign that makes it difficult to gauge the effectiveness of remedial action.

[GTO]

First things first:

The first thing you should do is switch the air-conditioner off, keep the revvs to a minimum and find a safe parking spot. Once you come to a halt, switch the engine off immediately, but position the key in “ignition on” mode. This will allow the fans to keep running. Contemporary cars have electric cooling fans that operate even when the engine is switched off. Pay attention to whether the fan kicks in or not (you will hear it) as this information will help us later.

Ensure nothing is blocking the front of the radiator (e.g. plastic bag or newspaper). Also open up the bonnet. Keeping the bonnet open will allow heat to escape quickly. However, if you see steam coming out from the bonnet area, don't go near it. Wait for the heat to subside or call for professional assistance.

There is no airflow aiding the cooling system at 0 kph and the components have to work harder to keep things cool when the car is standing still. The steps above help to minimise damage.

If the Radiator is Empty:

• Look at the coolant overflow tank (usually a small plastic tank connected to the radiator). If fluid level is below the minimum mark, there is a good chance that your radiator is running low too. While you can top up this overflow tank when the engine is hot, in some cars (mostly European models), the tank is pressurised. If there is a warning around the lid, or the lid needs to be screwed off (not flipped open), you can be sure that it's pressurised. Don't open it in that case; wait for the engine to cool off.

• We need to ensure that the radiator is topped up with coolant and water. Remember, you should NOT open the radiator cap when the engine is hot. It's literally a pressure cooker in there and you could end up severely burnt. Therefore, wait around for a minimum of 45 minutes. Go get yourself a snack or try to find a mechanic close by. When the engine has cooled down, slowly open the radiator cap with a thick napkin or cloth placed over it. It might release pressure and steam as you unscrew the cap, so do this very slowly.

• If the radiator is dry, you need to fill it up with coolant & water. If you cannot source coolant, use only water as a temporary fix. Be sure to start the engine before you start filling the radiator. This is necessary, else you'll end up with a cracked engine block. Keep the engine running and slowly top the radiator up with coolant and / or water.

A cooling fan gone bust?

• It’s unlikely that a modern car will ever end up with a bone dry radiator. If yours is, that hints toward a faulty fan or a leakage. Was the fan working when you initially came to a stop and parked the car in "ignition on" mode? To double check, once you have replenished the radiator, start the engine. After a couple of minutes of idling, the cooling fan should automatically activate upon your car reaching its operating temperature. If it doesn't, that's your problem right there. You could also try turning your air-conditioning on; many (but not all) cars will start the radiator cooling fan the minute that the air-con is switched on.

• Check the fan fuse. If it's blown, replace it right away.

• Even with a faulty cooling fan, your engine might be able to maintain its cool when cruising on the open road. However, the cooling system won't be able to handle traffic and thus, you should avoid bumper-to-bumper conditions at any & all costs. Fill your radiator and stick to open roads only. Maintain the highest gear & lowest rpm level possible. Switch the engine off whenever you come to a stop (e.g. at a traffic light). Keep a close eye on the temperature gauge; if it climbs to half or over, you should stop safely off the road and turn your car off.

The Heater Trick:

In either of the above mentioned situations, you can try switching your heater on to drain heat from the engine. Remember, your HVAC sources heat from the engine. The following steps might help in transferring heat away.

• Swing your air-conditioner temperature dial all the way to the red zone and the blower speed to full.

• Choose "fresh air" mode. Do NOT turn your air-con compressor on.

• Slide down all windows as the cabin will understandably become very hot.

• Move the air-vent's direction away from you, or direct air toward the windscreen.

• Switch the engine off whenever you come to a stop (e.g. at a traffic light).

• With some luck, the heater trick will keep your engine temperature within the safe zone.

The steps listed in this post might just get you to a repair garage without doing any permanent damage to your vehicle.

[GTO]

Radiator Leaking?

Radiators of modern cars usually last the lifetime of the vehicle. However, rust or damage can result in leakage. These leaks are usually accompanied by steam from the bonnet area (but not always):

• Adding a spoon of haldi (turmeric powder) when filling up water can help to plug minor radiator leaks. Be advised that this is only a stopgap measure to get you to a service station. At the first opportunity, you must flush the entire radiator and get the haldi out.

• If the radiator's leaking spot is visible, apply m-seal to that area once the engine & radiator have cooled down. It should hold until you reach a garage. M-seal is easily available in smaller towns too.

• If one of the hose pipes has a minor leak, you can try wrapping electrical tape generously around the damaged area. If the leak is at the edge of the pipe, see if you can cut the damaged area off and still have enough length to refit the pipe.

[GTO]

Professional Help

If the steps listed so far didn't help, you should have the car towed to a competent garage right away. Do NOT drive with your temperature needle in the red as it will destroy your engine.

If the mechanic nails it down to a faulty thermostat that refuses to open, ask him to remove it as a temporary quick fix. This will keep your car running cooler than normal, yet that's better than excessive heat.

Other overheating causes are a faulty pressure cap (unlikely if you are using OEM parts), a snapped fan belt (older cars only), blown head gasket, water pump failure, incorrect engine timing or a sensor gone bad.

For the Technically Inclined:

Here are two excellent DIY Articles:

Ifitjams.com

Aa1car.com

Once you are back home:

The above-mentioned remedies are listed only to get you out of a sticky situation. Remember to have your car completely checked at a competent garage at the earliest opportunity. Also, using 100% water in the radiator was meant to be a stopgap measure. You should flush out your radiator and fill it up with a manufacturer-recommended ratio of coolant : water.

Lastly, remember to flush your radiator every two years

Example of a dirty, ineffective radiator:


Image Credits : The pictures of this Article have been sourced from various Team-BHP threads. Thanks to BHPians for shooting & sharing them.

[GTO]

Thread moved from the Assembly Line to the Technical Section!

[rajeev k]

Another informative thread. Nice that the forum is focusing on these aspects also which is a boon to non technical members and other viewers alike. This snag happens to many on the road and I myself faced it once due to faulty fan switch which was immediately noticed and made it to the garage safely taking the precautions which you have compiled. Moreover I had helped many on the roads too who got stranded on account of overheating.
Another word of caution is to never open the radiator cap when the engine is overheated

Keep them coming. Your initiative has also prompted members to start such informative threads.

[ajmat]

Great topic

Let me add that if none of the above work, other failure points

Cooling System Airlock - this happens after you might have merely refilled coolant and driven off. Fill the radiator with coolant, keep radiator cap open (assuming engine is not hot!), let engine idle and top up.

Snapped Belt - Water pump is driven by a belt off the crankshaft. It also drives the alternator in most cases. If the charge light comes on and temp gauge rises, there you have it

Water Pump Failure - The pump sits inside your engine block and is driven off the crankshaft by a belt. The impellor might fail or the shaft might have snapped. Avoid driving and get the car towed since parts of the pump could circulate into the water chamber creating more damage

Consequences of OverheatingIf you see the temp gauge rise and stop in time, all is forgiven - You will get away with it

If above + you hear the water bubbling - You have just got away with it

If above + water spewing in the water compartment - You might or might not have got a away from it

If above + steam +water in the oil+ steam in the exhaust - You will need a new cylinder head gasket but you might need to get the head machined - your car might not be exactly the same after that unless professionally done and tolerarances monitored

If above+ knocking and complete stopped - Engine has seized - Game over!

[Rehaan]

Nice concise guide GTO. Thanks!

Over-heating is a problem thats become much less common with modern cars. At the same time, that means that less people know exactly what to do when faced with the situation.

I know a lot of people love the analog temperature gauge, but i think for the masses a suddenly appearing temperature warning light is probably more attention grabbing than one small gauge of several, thats always present.

If you miss the warning signs, other symptoms to indicate overheating can be :
- Engine begins to knock severely only after you've driven for a while
- Car stalls suddenly and cranks, but refuses to start. Magically starts running fine when you try again after a few minutes


Also note that sometimes when you see smoke/steam coming out of your engine bay, it could be caused by some other fluid leak (not necessarily coolant). Eg. the old Fiestas whose power steering fluid line travelled over the engine block and would sometimes crack and leak.


Lastly, remember that steam burns are even more damaging than boiling water burns! It's the exothermic state switch-back from gas to liquid that releases a tremendous amount of energy. Wait an extremely long time before playing with any part of your coolant system. Ensure you use a thick cloth as mentioned, and also keep your face out of the way as an added precaution.

cya
R

[mycarhasablower]

Originally Posted by GTO

Attachment 1041880

If the Radiator is Empty:

• If the radiator is dry, you need to fill it up with coolant & water. If you cannot source coolant, use only water as a temporary fix. Be sure to start the engine before you start filling the radiator. This is necessary, else you'll end up with a cracked engine block. Keep the engine running and slowly top the radiator up with coolant and / or water.

.

About the WATER. there are a lot of places that get hard water and even otherwise soft tap water has a considerable amount of dissoved salt in it which accelerates corrosion of the engine internals, so using RO WATER is the best idea for maximized life or just get premixed coolant. In short NEVER USE TAP WATER

Originally Posted by ajmat

Great topic

If above + steam +water in the oil+ steam in the exhaust - You will need a new cylinder head gasket but you might need to get the head machined - your car might not be exactly the same after that unless professionally done and tolerarances monitored

Id like to add what i know about this. Often we machine heads when they are warped. And the most common cause of warping is overeating. While people always get the head faced and think its as good as new; it most certainly isnt.
the heads from older pushrod cars like the fiat will probably function just as well as new ones but todays cars have overhead cams. And when a head warps , the bearing bores for the cam also go out of alignment and arent concentric anymore. Therefore the engine ill never be as smooth as before since there will be resistance in certain parts of the 360 degree rotation. So yeah,a new heads a good idea if you really want to keep the car. Or just make sure that you dont let your car overheat in the first place

[a4anurag]

This is the problem that I am always worried off. My Ritz does not have a Temperature gauge in the console so it is difficukt to judge what condition the engine is in.

Never faced this issue till date and make sure not to drive at higher RPM's or revv the engine to the limiter anytime.

[infotech58]

Excellent Article!
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?


I faced overheating in my OHC sometime last year but luckily noticed the temperature gauge rising in time and stopped. Drove to a mechanic once the engine was cool and found that the expansion valve was jammed preventing the flow of coolant.

Originally Posted by GTO

• If the radiator is dry, you need to fill it up with coolant & water. If you cannot source coolant, use only water as a temporary fix. Be sure to start the engine before you start filling the radiator. This is necessary, else you'll end up with a cracked engine block. Keep the engine running and slowly top the radiator up with coolant and / or water.

[Desmosedici]

Same question as what Sumeet has asked.

Last year post service of my Honda City, i had to encounter such a situation. The service center had flushed the radiator without informing me and then there was a leak which was plugged by Mseal which eventually came off within a few days. I was stranded at around midnight on JVLR. I had to change the radiator and now all is well.

[subratasenn]

Originally Posted by a4anurag

This is the problem that I am always worried off. My Ritz does not have a Temperature gauge in the console so it is difficukt to judge what condition the engine is in.

Same with many other cars. The Etios for example. Only the "overheating" sign will show. It was better to have a temperature gauge.

[a4anurag]

I fail to understand what manufacturers get in omitting one gauge from the console and what reason it could be?!

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

Damn Engineers!

[aaggoswami]

Would like to add something.

Never open radiator cap as long as you cannot do it with bare hands. The reason behind this is pretty simple. If you are not able to touch the radiator cap with bare hands, it means the system is still hot and hence, pressurized. Opening the radiator cap will result into a fountain of fluid coming out ( if there is fluid of coolant+water ). If you are not able to move your face out of the path of erupting fluid, you are going to get seriously hurt.

How I know this ?

Well, in our M800 which had CNG, the coolant was running low and in the supreme heat of Gujarat, the engine temperature was higher than normal. Now this car was old and was serviced at local workshop. I took the car to him, his worker opened the radiator cap when the system had not cooled down. Immediately there was a fountain of green liquid that went to as high as 8 feet in the air. A few small drops on my forearm took more than a month to heal fully.

Please, never open radiator cap till you can do it with your hand, as if you are able to open with hand, the system has cooled down sufficiently for safe operation. If not, its hot enough to harm you if there is liquid inside.

Also, remember the concept of steam engine ? Steam has more latent heat, can give you more severe burns than hot fluid. Take a note of this point also. This is important when you have no fluid in radiator and you open radiator cap for filling in water or coolant of water+coolant.


The newer systems in atleast some commercial vehicles are such that they do not have filling points on radiator, but still the system is pressurized and the only filling point is the coolant overflow/reservoir container.