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-   -   What to do if your Engine Overheats on the road (https://www.team-bhp.com/forum/technical-stuff/131650-what-do-if-your-engine-overheats-road-3.html)

Many new age generation vehicles don't have the temp gauge in the console, even the BMWs don't have them, they give over heating warning signs only, i believe there should be an option to have that on the console especially for those electronic consoles.

I think this trend of eliminating analog guages and relying more on electronics was started by the German cars. Their affinity towards flat beds also started around the same time if I'm not mistaken.

I remember an incident which took place some 15 years ago! We were travelling in my friend's brand new Maruti 800; barely a few hundred kms on the odo and the engine started knocking. We immediately peeped on the gauges to find the temperature needle trying to even overshoot the 'H' mark!

We parked the vehicle immediately in the side and when we got out, it was literally steaming & there were marks of coolant on the bumper which had gushed out from the radiator. We let the engine cool down sufficiently & drove to home cautiously in low rpm. Fortunately, we were not too far away...just 2-3 kms.

Took the car to MASS next day and a faulty relay was the culprit. This relay signals the radiator fan to start when engine becomes hot to cool it down. Failed (in this case, read - Burnt) relay meant no signal to the fan and hence the 800 fumed!
As the car was almost new, the relay was replaced by MASS free of cost. I still remember, the total cost was about Rs. 800/-.

This happened in my old Zen D. We used to get frequent overheating and each time the service center would replace the fuse. Like GTO mentioned in the begining, the trouble would only crop up in heavy traffic and go away if the car reached 40kmph. The issue was that the fan would not work as the fuse would have blown due to a faulty relay. The worst part of this was that the HYD A$$ just kept replacing the fuse for three years. It was only after I moved to CHN that a workshop person was able to identify teh root cause and fix it once and for all. I spent a good amount buying fuses :deadhorse

About those electric fans..If fitted with reversed polarity, it will add to the over-heating woes.

Also, its a good idea to watch out for any air bubbles or oil mixed with coolant/water in the radiator/expansion tank, when you pop up the bonnet for that "general well-being" check every other week. Both would mean compression leak (most times, the head gasket). The earlier its diagnosed, the better for both the owner and the car!

I had to go through this once as the idiots at Ford forgot to reconnect the grounding wire for the electric radiator fan on my Ford Ikon. A little presence of mind saved the car. First signs were the AC cutting off though it made me worry about some AC related component failure. The AC cut off after driving for just 4km from a cold engine. I decided to continue driving with the windows rolled down. I don't watch the temperature always but this time I did and it was crawling up slowly. I knew the engine was going to over heat, pushed to reach my destination as it was less than a km away and when I noticed the first sings of steam, I turned off the engine. Lucky for me that when it did steam I had just parked my car and was about to turn off the engine. No damage at all and I lost just a few ml of coolant which was pushed out of the coolant tank pressure cap. The location of the coolant tank on the Ford Ikon is such that it steams up the windshield on the drivers side. It does not hamper vision in any way though the sight of it is scary.

I have a question: what effect does overheating engine have on the engine oil? Should the oil be changed if the engine has overheated? I recall someone once telling me that once a engine over heats, it best to change the oil along with all other remedial work as the oil starts to deteriorate quickly.

Another question: Probably an extremely rare situation? What if the temperature sensor has gone bad? or stuck at the normal operating temperature position.

What could be the signs that there might be something wrong in the cooling system and the vehicle is overheating?

@honeybee mentioned the blinking light on the dash, what if that bulb has fused?

@Pratik,

Apart from providing continuous lubrication, engine oil also facilitates cooling of the engine by 'flowing' the heat away. Also it helps in cleaning the sludge formation...so engine oils are just not for lubrication.

If we go deep down the study, we will find that oil goes both thermal & mechanical degradation. This degradation breaks up the oil over a period of time due to heat, sludge & normal wear, which in turn makes oil lose its basic functionalities stated above. Now, its pretty clear that any abnormal heating will hamper the engine oil and result in break up, hence, change of oil should be a must
1. if the engine has been in an overheated state for a prolonged time
2. if the oil has done more than 2000 kms. as it would degrade at an alarming rate after running 2K kms.

I would personally prefer changing the oil as soon as possible.

@ mmxylorider:

If your gauges show faulty/ normal range reading for an overheated car for any reason, the engine & driveability will show up pretty soon after. You car will lose power & grunt due to incorrect fuel detonation and may soon be steaming too. Erratic ignition of fuel will lead to a knocking engine. A careful & experienced driver will notice these things pretty soon. AC will cut-off, if its on and coolant will be boiling and there is a high probability that it will gush out of the radiator cap. Most of the syptoms are easily felt either driving or even sitting in the such vehicle. Please remember that overheating of the engine can cause irrevisble & severe damage to the engine. The engine can also be destroyed beyond successful repair!

Hope that helped!

Regards.

OT: Is it necessary to keep the engine running while replacing (not topping up) the coolant? I do not remember this being done when I got the coolant changed.

This is a grey area. If the engine overheats over a short distance the oil should not degrade. With prolonged overheating the addictives degrade, but the base oil does not

Easily checked. If the coolant boils over it is bad. If not carry on normally

Normally the overheating light will go on (if there is no temperature gauge). In extreme cases you may feel the heat. The engine note changes and in most cases the performance drops.

. Never replace the coolant when the engine is overheated. You may crack the block/head.
. Wait for at least 15 minutes before opening the radiator cap, else hot steam may scald you.
. After the wait start the engine and let it run for a couple of minutes. The open the radiator cap and it all is normal slowly add the coolant, In case you feel that the majority of coolant has drained away, wait at least an hour for the engine to cool down before adding any coolant.

NOTE
Adding coolant to a hot engine will warp/crack the head/block.

Here's incidence happened in my recent visit to native place (Sawantwadi). I was driving Mumbai-Kolhapur-Gaganbavda-Sawantwadi-Goa route with night stay at Kolhapur.On day II, when I started from Kolhapur to Sawantwadi, while descending ghat section my brother's Innova (2005) temperature gauge started pointing in red zone. I Pulled over at safe zone to check the problem. After opening the bonet, I discovered steam coming form leakage at the joint on overflow hose connecting upper tank. Water level was well below 'LOW' mark. I waited till engine was cooled down and checked the hose connection. Joint was broken and was leaking steam/Hot water through it.

After engine was cooled down, I topped up radiator with water and started the car to search for nearest garage. First garage spotted was tractors engine repair shop and I Pulled over. After looking at the situation, he advised me to block the upper tank overflow outlet with mseal and let it go:Frustrati

It sounded so stupid and I escaped from there and reached another mechanic 15 kms away. he's given 'Jugaad' solution so that I can drive to bigger city where I can find Toyota Dealership/service station.

Steps:
1) Let engine to cooled down
2) Cut off damaged section of the hose.
3) chopped off broken half of Overflow outlet.
4) Placed small metallic hollow cylindrical piece of tube at outlet and Joined it together with hose pipe.


5) Covered this Jugaad assembly (hose+metal piece+overflow outlet) with mseal to make joint.


6) Topped up radiator with coolant.

With this quick fix, I managed to return to Mumbai. Now I want to fix this problem and I have figured out two alternatives

1) Source Upper head of the radiator from Junk market and fix.
2) Get Genuine spares (comes with radiator upper tank and hose assembly).

The car is normally driven in city (monthly 800-1000 kms) and rarely taken out for long drive. Replacing radiator will cost more than 10k and I'm not willing to spend that much unless its necessary. Please advice should I go with genuine spare or source it from Junk market.

First generation Wagon R owners might find this information useful. The temperature gauge will not read if there is no water in the radiator, coolant tank. It will indicate cold and if you see this, pull over immediately or you are going to seize your engine. The way the temperature gauge is setup in this car, according to me, is very bad design. Many mistake the lack of any temperature indication as a busted meter or sensor. If you are driving and you suddenly notice the temperature gauge not registering anything, pull over check your cooling system levels.

A very useful and an informative article. Thanks for sharing this information GTO. Many modern cars don't have the temperature guage; so I always wondered, what would the driver do in case of overheating, since the light on the panel would come on only if the temperature reached a certain level. Some very thoughtful insights too from others, on what to do in case of such situations.

Regardless of where you drive i.e city or hwy I'd strongly recommend replacing the radiator assembly. There are higher chances of overheating in the city with bumper to bumper/stop and go traffic.

The jugaad joint is not going to last forever as it has corroded. You really dont want to take a risk with an engine seizure just to save Rs 10K!

Go with the genuine radiator assembly and make sure you only add Toyota's recommended coolant as a refill and for top ups.