Car overheat & leaving radiator/coolant cap open

Last Sun night, my car couldn't start (despite turning the key many times)  & appears to be rather warm in passenger area: see the 2nd attachment on how the meter/dashboard of the car looked like at that time.

Towed to workshop next day who said 2 motors (that circulate coolant or air??) needed to be replaced so they're replaced but next day, it gets heated up & when I checked the coolant, it's empty.  So I top up with water (instead of coolant) to the full & checked if there's leakage but no leakage is visible.

Next day, found that there's no water  anymore so I top up with almost 2L of water & drop to the workshop:
the mechanic pointed out to me (refer to 1st attachment, yellow-highlighted area) that boiling water is seeping out: he said that the engine is malfunction, generating too much heat thus the boiling water expand & seep out through the yellow-highlighted area.

He said need to overhaul the engine or change another engine & he can't think of any other options.
Anyone has any other opinions or how I could fix this without incurring huge expenses.

 In the meantime, he suggested I could top up with water every 30-40 mins but it's going to be too hot
& dangerous to open the cap (see 1st photo, bottom right corner) : will it be Ok if I leave the cap open
so that I can stop the car every 30mins by the roadside to top up water to cool the engine?

My car is Honda Airwave 2009 model
Carburetor_coolantLeak.JPG
CarDashBoard.jpg
sunhuxAsked:
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sunhuxAuthor Commented:
The mechanic said it's not the radiator that's leaking but it's the engine that generating too much heat so something's wrong with the engine that needs engine overhaul.

Worth replacing that white plastic container shown the 1st photo & radiator which is much cheaper??

In the meantime till I get to another workshop, what are the interim measures I can take so that the car don't get damaged further?
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sunhuxAuthor Commented:
Is there any radiator cap for Honda Airwave that has "pressure release" & yet the cap won't feel hot so that it's safe to open every 30-40 mins to top up water?    How much water should I keep for a 2 hour drive assuming all water in radiator will be gone after every 30 mins?
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RaminTechnical AdvisorCommented:
leave it for one day  and check under the car for any leakage.
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Bill PrewCommented:
Running the car without a radiator cap for more than just a few minutes will not work.  Coolant systems on cars are meant to be a "closed system" to work properly.  As water heats it expands, and with the radiator cap in place the pressure in the coolant system increases.  As it does, this increase in pressure raises the boiling point of the water.  Without the cap in place there will be no pressure in the system and the water will start to boil sooner, and overflow the radiator.  Not a good situation.

Hard to diagnose from a distance, but if you are really losing that much water that fast, and can't see it leaking out, then it may be entering the engines cyclinders and heading out the exhaust with the burned exhaust gasses.  This is often caused by a bad cylinder head gasket, or much worse, a cracked cylinder.


»bp
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sunhuxAuthor Commented:
I did that but don't find any water leak previously : perhaps that's when all water had leaked while on highway or after they've evaporated.

After the car had been stopped for several hours, I can now smell something burnt in the passenger compartment.

Someone on yahoo suggests to close the radiator cap not fully tightened so that the pressure can escape & I could safely remove the cap to top up water every 30 mins .... good & safe idea?
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Bill PrewCommented:
Do not run the car without a proper cap, tightened and sealing properly.  You will in all likely hood overheat the engine and cause damage.

Get the car to a second mechanic that can do some good diagnostic work and give you a second oppinion.


»bp
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RaminTechnical AdvisorCommented:
if that amount of water was entering the engine at least you would have some issues related to staring problem or you could see dropping water on the rear side of your car (from Exhaust) or intense humid when you keep your hand close to it.

I still suggest don't move that car.  fill it full of water,  leave it for one day and check for leakage under it carefully, also check if water level changed.
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Bill PrewCommented:
Rereading your original post, I'm curious what the initial replacement the shop did were?  Do you have any details on those.  There are no "motors" that circulate the coolant through the engine, it is done via the water pump, which is a mechanical component integral to the engine.

Also, "filling an engine with coolant" is not as simple as it sounds.  You would want to remove the radiator cap and pour the coolant directly into the radiator, not just fill the reservoir tank.  But it can take a while for the coolant you fill into the radiator to work it's way into the engine, and often only happens after running the engine for a few minutes.  So you may have to fill, wait a while, fill some more, repeat.  And run the engine for 1 minute r so in there and then check if more water is needed.

Keep in mind that adding just water is not good, you need to proper mixture of coolant and water.  Just water will have a lower boiling point that mixed coolant, and will overheat sooner.

Lastly, I would try replacing the radiator cap.  It's a very inexpensive part and if it has failed it will allow coolant to bypass it at too low a pressure, into the reservoir, and likely overflowing it.  


»bp
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RaminTechnical AdvisorCommented:
Make sure the coolant / water is not leaking inside your car ( beneath the driver feet) .
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BillDLCommented:
Remove the oil filler cap and look at the underside.  If it is is covered with light grey slimy sludge, then there are usually two possibilities:
1. You only drive short journeys every day and it is caused by condensation.
OR
2. Water from your radiator coolant system is getting into your oil and emulsifying.  The usual cause is a leaking cylinder head gasket, and if this is the case your car would usually have other symptoms.  Overheating would often be one of those symptoms.

Test to make sure that the thermostat on your radiator cap is working properly.  The following video provides some good information about this:
https://www.youtube.com/watch?v=AOSRVxA_RRQ

If the thermostat in the radiator cap is defective the water can overheat and become too pressurised.  It can boil over in the plastic expansion tank and overflow from it or even force its way out of the hoses connected to the expansion tank.

These are simple things you can check before you take the word of a mechanic who tells you that "the engine is malfunctioning, generating too much heat".  As Bill Prew suggested, you could buy a new radiator cap.  If this is the only thing that is faulty, you could have saved yourself a lot of money.
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dbruntonCommented:
Originally it looks like you've had water pump failures and the mechanic has replaced those.  However there have now been other failures.

The white plastic container is your overflow tank and is meant to take excess water from the radiator when the engine gets hot.   It is only designed to take about a litre of overflow.  When the engine gets cold this water is sucked back into the radiator.  However if the radiator expels too much water then the overflow tank will leak this water which is what is happening here.

The radiator is getting too much hot water and can't handle it.  It appears that the cooling system isn't working correctly which could be one of a number of problems:  water pump failure, thermostat failure, collapsed hoses. sludge in system, incorrect pressure cap on radiator, no anti-freeze, radiator fans not working, blocked radiator and engine failure.

There should actually be signs of overheating on your temperature gauge.

You can try and alleviate the overheating by running the car heater.  This will warm the car up but it will also help get rid of excess heat.  The higher you run the heater the better.  Don't try running the engine with the radiator cap off or half-turned, this isn't going to help in this situation.
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sunhuxAuthor Commented:
Radiator no leakage but engine heats up too fast (was 30mins previously before the Temp meter hit max  but last nite it hit max within 5mins of driving).   The invoice of the pair of $400 motor repair simply says 'motor' n I guess its the pump that DbRunton said.

Too many problems including gearbox n engine mounts replacement lately with this 9yo car.  Anyone cud suggest a 6 or 7 seater hybrid Japanese car?
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dbruntonCommented:
Get the garage to take the thermostat out and test it.  If it proves faulty then replace.  If it proves OK leave it out.

This is a very temporary method of keeping the temperature down and is NOT good for the engine in the long term.  It will or should stop the temperature reaching maximum temperature.
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sunhuxAuthor Commented:
> Make sure the coolant / water is not leaking inside your car ( beneath the driver feet)
There's none.

>Don't try running the engine with the radiator cap off or half-turned, this isn't going to help in this situation.
Last night I kept the radiator cap about more than half turned (with about 30% away from the max it could close):
I guess this must be the reason the temperature (as shown by the Temp meter) rose rapidly after 5 mins of driving.
Ok, will turn it to the max so that it can last at least 30 mins (which was the duration previously when cap is tightly closed)

>1. You only drive short journeys every day and it is caused by condensation.
I drive a total of about 20-30km daily,  sometimes my wife will drive to nearby supermart around 1km away to buy
groceries in the evening.  How to verify if it's due to condensation?

>2. Water from your radiator coolant system is getting into your oil and emulsifying.  The usual cause is a leaking
>cylinder head gasket, and if this is the case your car would usually have other symptoms.
Other symptoms I encounter are vibration / coughing

The video on testing the thermostat is too complex for me to do
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sunhuxAuthor Commented:
Just top up water into both the white container n the radiator four hrs ago n parked at a dry carpark lot.  2 hrs ago *ie after parking there for 2hrs, I found there's a wet spot directly below the radiator tho the engine is not hot *ie not due to spillage of boiling water fr that white container
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sunhuxAuthor Commented:
From last night parking at a dry lot, I checked again & found the spot directly
below the radiator has a 30-40cm wet spot : on feeling it, it feels like a mix of
water & oil (though I'm not certain if the oil is from a past dried spot of other
cars).  I topped up another 1.9L into the radiator (which was full last night when
I parked).

Radiator cap is good as confirmed by mechanic & when it's hot, don't see any
steam escaping from it.

I'm going to another workshop to change the "cylinder head gasket" & 
"thermostat"
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sunhuxAuthor Commented:
>issues related to staring problem or you could see dropping water on the rear side
>of your car (from Exhaust) or intense humid when you keep your hand close
Don't find the above issue ie no drips from exhaust area on floor nor intense moisture
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dbruntonCommented:
Get your thermostat checked first.  You may not need to do your head gasket if the thermostat is faulty.  I think there's a quick test involving feeling the two radiator hoses but the mechanic should know the test.

Check your engine oil and your radiator water.

For the radiator water you are looking for an oily sheen on top of the water much like a rainbow.  If you see that you've got serious engine problems.

For the engine oil look at the underneath of the filler cap.  Whitish condensation there may mean water leaking into the oil.  Milky oil means water getting into the oil.  That again is serious engine problems.

But the mechanic should know how to check for those problems.
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RaminTechnical AdvisorCommented:
The first and most important thing that you have to know  is to find the leackage place.
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dbruntonCommented:
>>  The first and most important thing that you have to know  is to find the leakage place.

I suspect this is the overflow bottle.  The hot water is coming from the radiator into the overflow bottle.  This is the white plastic bottle attached to the radiator.  Too much water is coming into the bottle and it is overflowing.  The engine is getting too hot and the radiator can't handle the heat and hence the pressure cap is releasing the water to the overflow bottle.
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sunhuxAuthor Commented:
I'm going to another workshop in 3 hrs time to check where it leaks exactly, change Thermostat & get 2nd opinion.

Last nite I top up the radiator to the full & when I tried to top up early this morning, both the
radiator & white container are full.  I managed to drive for ten minutes before the Temp meter
hand hit about 65% & after another 5 more mins, the hand hit max temp & then came down
to about 80% after staying at max for about 2 mins.  Does this phenomenon means
Thermostat issue?
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dbruntonCommented:
Possibly a [sticky] thermostat problem but the garage should be able to determine if it is or not.

There could be other causes.
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sunhuxAuthor Commented:
the 2nd garage (a much bigger one) just replaced the thermostat: he confirms there's no leakage of radiator & the white
container & the engine is intact : he test drive for 10 mins & the temperature did not go up.  Thanks for all the suggestions
here which I forwarded to the 2nd garage.   Let me test drive it for 2 more days before closing this thread
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sunhuxAuthor Commented:
2nd garage said the  frequent   'choking' or 'vibration' while driving is not there anymore after replacing thermostat
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sunhuxAuthor Commented:
I've collected the thermostat-replaced car : after test drive for 25 mins, the temp stays at around 40% mark (ie below 50%) : some 'choking' or intermittent 'vibration' can still be felt though it's less pronounced & less frequent: does this symptom mean the engine is affected?
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RaminTechnical AdvisorCommented:
some 'choking' or intermittent 'vibration' can still be felt

It can be the spark plugs. intense head might damaged them.
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dbruntonCommented:
>>  some 'choking' or intermittent 'vibration' can still be felt though it's less pronounced & less frequent: does this symptom mean the engine is affected

Could be anything, a problem that existed before the overheating or caused by the overheating.

Ramin suggests spark plugs.  If they are very old they could need replacing.  Also spark plug leads could be old and faulty.  But the problem could be anything.  Engine or gearbox mounts for example.
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sunhuxAuthor Commented:
It doesn't appear to be gearbox as I've replaced the gearbox about 5 weeks ago when it gave this intermittent
'choking' or 'misfiring' & since then it's smooth ie don't get this 'choking' prior to this overheating case.

I've driven for 1 over hour today and the Temp meter stays at 40%.

Ok, will check out the spark plugs as that's not an expensive item.

So it won't be like massive carbon/tar build-up in the engine due to the last few days' overheating?

I was told to check the gaskets in the engine, the engine has to be opened up & this is a massive effort, true?
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dbruntonCommented:
>>  So it won't be like massive carbon/tar build-up in the engine due to the last few days' overheating?

No carbon buildup.


>>  I was told to check the gaskets in the engine, the engine has to be opened up & this is a massive effort, true?

No need to open engine up.  Keep an eye out for water and oil leaks.  Especially around where the head and block meet.  Check oil and water colour and that the levels don't change dramatically.  Oil should not go creamy white.  Also possible compression leaks if the head gasket goes, you can feel air leaking out.

Temperature gauge should take about 2-3 minutes to reach correct level and should hold that level throughout your driving range.

If you're getting a little bit of missing or misfiring it is very hard to say what could be causing that.  As before could be almost anything.
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sunhuxAuthor Commented:
Surprisingly starting from yesterday morning (about 36hrs ago), the 'choking' (or sort of misfiring) are
almost gone.  The engine or spark plugs  self-clean ?
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dbruntonCommented:
No.

The problem probably wasn't the spark plugs.   Run the car for a week and see if the misfiring comes back or is totally gone.
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sunhuxAuthor Commented:
Thanks very much everyone;   the car is now much better off than when I was first told the engine needs overhaul.
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BillDLCommented:
Thank you sunux
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