I have a Honda Civic 1.5i year 2000 model.The water in the water tank keeps dissapearing overnight but the radiator is always full though.The head gasket blew 3times already and I replaced it,but I still have the problem with the water that is dissapearing from the water tank,even if the car is not driving for a day or two.There is no visible leaks anywhere and I bought a new radiator.Any help PLEASE???

Asked by Mar 10, 2017 at 10:14 AM about the Honda Civic Hatchback

Question type: General

6 Answers


If the coolant disappears from a parked car with no engine running for a day or two, then it HAS to be from a leak. If the degas bottle drains in that time then it's not a small leak either, you should see some puddling of coolant under the car. However if you ARE driving or running the engine in that time, then it could be going out the tailpipe (headgasket) or boiling over (engine overheating and boiling coolant flowing out overflow to ground), or even trapped air in system, if it was never properly bled/burped after previous work (trapped air can expel coolant when purged from system). It's too early to just assume you have a bad radiator, you need to assess what is going on with cooling system. Check for flow/restrictions, pressure test cooling system (look for leaks - you can rent/borrow apparatus from any auto parts store), check for hydrocarbons in coolant (with a product called Block Tester, again can be rented/borrowed from any auto parts store), you can also recheck cylinder compression to make sure head gaskets aren't blown. You don't mention overheating with engine running. You should also check oil for coolant contamination. Check radiator for flow when engine reaches operating temp and thermostat opens. Check condition of radiator cap, a bad/cracked rad cap can prevent degas bottle from functioning properly. Finally, do yourself a favor, since your radiator does have a radiator cap, open it and bleed/burp air from system, and top off coolant, see if that doesn't improve anything, you can Google instructions for bleeding air from a cooling system for your make/model car.

First symptoms after 3 to 4 weeks of replacing head gasket: (besides water dissapearing from tank overnight),car drives perfectly fine for about 3 weeks then: while driving the water starts to boil in the tank then the heat gates go up while we driving the water boils out of the tank the radiator's water doesn't boil or leak no water has been found under the car after the boiling of water(not long) we find that the water mixed with the oil. Some mechanics said that my top or my block might be cracked/damaged but the top has been schemed and pressure tested 3 times(with replacing of head gasket set) and the block has been checked but no cracks/faults were found. radiator cap was changed on previous radiator too Do you think the problem starts with the water dissapearing?Is that the main problem that causes the head gasket to blow everytime?

how do i bleed/burp the air from the system?


A blown head gasket can over-pressurize the cooling system, not only can it force coolant out, it can cause it to boil. The fact you are still getting coolant into the oil is a pretty sure sign you have a blown head gasket or a cracked water jacket in the block. The shop that replaced the head gaskets may have checked the block but to resurface the deck (the surface the heads attach to) requires machining and that's only done with the engine pulled out and block stripped down. From what you are writing, you only had the head gaskets replaced and mating surfaces cleaned. Being that you also say you are on your third set of head gaskets, clearly this block or the heads are toast.


To bleed air from cooling system (you can Google this for a more-thorough description with pics) - first park car facing uphill, or put front end on jackstands or car ramps. You want the radiator to be the highest point in the cooling system. Remove rad cap. Have a bottle or pre-mixed coolant handy. Run engine - when it reaches operating temp, thermostat will open and you should be able to see coolant in radiator get sucked into lower rad hose. As this happens, coolant from engine will flow out of upper hose into radiator, and hopefully also expunge air trapped in system at same time. Make sure heater is on when doing this. As coolant level drops in radiator, add new coolant into center tube (when you look down into radiator cap opening you'll see a tube that comes up nearly to top of radiator) Just keep adding coolant to prevent level in that tube from going down too low (if it does it will suck air back into system). When coolant level in radiator is maxed out you should have all air out, however it may take one or more tries to get rid if it all 100%. Just don't run engine for TOO long with rad cap off, coolant does reach about 185-200F. Most newer cars with degas bottles and no radiator cap don't follow this procedure, but AFAIK yours does.

Thank you for the info.What do you think I should do?Get a new enjin maybe?

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