This morning before I went to work, I open the bonnet and check the coolant and notice that the coolant is below LOW, because the car was cold so I think it's ok, so I start driving to work. After 20 mins driving I open the bonnet again and see the coolant level is between FULL and LOW. Do I have to fill up the coolant if it's below LOW when car is cold? I also notice after I drive on the motorway in cold night, the temputure garage drop down. I know once the car is up to tempure it will never drop down. This issue been around for a while now.

 

lol thats completely normal mine will fluctuate like that and has been doing it for many years, overnight MOST of the time it drops down and when theres more pressure and heat in the radiator after driving it should push back some into the overflow tank. As long as it doesnt drastically fill up like completelytop off the reservoir or empty completely than you shouldnt have any problem

 

There should be a warm and cold max.

 

just fill it to the max line when cold... your engine is fine, the best way to know if you have a failing headgasket is to go WOT several times, pushing the car hard, then pull over and check if the coolant is flowing out of the reservoir, then you have serious problems.

 

Another way to chexk is pull your dipstick if there's white crap mixed in on the dipstick its a sign the gasket is blown but I doubt it is.

 

Just to be clear, this is not how to find out if you have a failing head gasket.

Your car is completely normal though.

 

The best way to cheek is fill up the radiator up and leave the cap off.

Start the car and leave it running for a few minutes, If it bubbles there is a high chance you have blown headgasket. Much easyer on the motor then doing wot pulls.

 

Just go wot and if it goes KABOOOM! you have a bad headgasket. haha

 

LOL, adriano, not following you but yet again some funny **** going on in your posts. I can't believe people actually believe beating on your car and putting your face over your extremely hot motor is the way to do things.

OP, just as it was said before, there are many ways to check head gasket failure.
-one, if you are having temperature fluctuations and you have not changed the thermostat or bled the system....change it and bleed the system.
-two, perform a compression test and make sure the results of each cylinder dont vary more that 5% or so
-three, take a look at your spark plugs, if you are burning coolant because the worst has happened (head gasket blew towards the cylinder) then it will result in a frosty looking electrode.
-four, if you dont see any milky substance in your oil or coolant res tank then you may just be lower on coolant in the block than before. you have to remember that coolant in the block and pump are going to settle and may result in lower coolant tank readings and as the block warms up and the coolant was moved around by the working water pump you will have or may have different readings that with a cold engine. Good luck and I hope this helps.

oh btw, do you beat on your car regularly and how many miles are on the car?

 

Or buy a Block Tester

 

If you responding to my post i didn't say to put it over your car when its hot

 

Just want to add that even if your oil and coolant aren't mixing, you can still have a blown headgasket (as was my case).

 

17pstockcar, i know man. it was a joke.

Raptord, this is very true. I have seen where a car was overheating and actually was so bad that the head had to get straightened and the cam bores had to be realigned and it started from the head gasket going bad and the thermostat never being changed. he didnt have oil and coolant mixing either but it was surely eating it.

 

All good was just making sure others knew not to do it when its hot haha dont need Bolling water splashing around and burning people.