Why is my coolant boiling??

[racin-type]

This happens everytime i drive the car for a long period of time (1-2hrs). After i shut off the engine i notice water vapors rising out of my hood. Upon inspection i see that its boiling coolant from the coolant resevior bottle and its waaaay past max and actually bubbling out of the bottle's escape hole. but after its cool the coolant is right at the MIN level.

Some background info: just got the car, and only added coolant cause don't kno how to flush it yet(waitin for my FSM).

can anyone tell me whats goin on?

and oh yea my engine does not overheat.

[gabossie]

flushing it is really easy. Drain it, the plug is on the bottom of the radiator, I believe on the drivers side. Then with the plug out, run some water through it until it's comming out clear. Also drain the resivior if you want. Plug the radiator and fill with your mixture or coolant and water.

**note, I don't believe that this flushes the coolant out of the block**

[NISTECH]

if the car is not over heating it could just be a bad radiator cap replace it their cheap. To flush the system use this approach for a good flush.Do as he stated to drain the radiator. Then pop off your upper and lower hose from the radiator. Stuff your garden hose into the upper rad hose and run water in there. If it backs up and is hardly coming out of the lower hose. Pull the t-stat out and run the water in the t-stat opening. this will flush the block. the only part that may not get flushed 100% is the heater core but that is minimal amount of coolant. If you pulled the t-stat replace it as preventative maint since your already there. Put the hoses back on. Top her up on 50/50 coolant/water mix. Make sure you remove the bleeder screw located on the intake manifold when filling or you'll get an air pocket. It also helps on the 240 to have the front of the car elevated when filling. after doing this if it still over heats(boils over) after a long drive. It could be a restricted radiator or a bad clutch fan. The clutch fan should turn by hand when off but with some resistance. If it just free spins you have a bad clutch and should replace it. If that checks out ok then you may need to have your radiater rodded out. but these 2 conditions only apply if it is over heating.

[vududoc]

possible bad water pump or build up in rad....hopes its build up.partially stuck thermo aswell

[SloS13]

while you're in there, go ahead and replace the thermostat

[CanadianCoch]

First things first, you have to find out what the problem is. Searching would definately find you the most answers, but i'll try and provide as many as I can.

First thing to try is seeing if you have an air bubble. At the end of this essay is the procedure to do a PROPER bleed of the coolant. This is the cause of most people've overheating. FIRST do this, and if it does not fix the problem, proceed through the following steps to find your problem.

1. Does your temperature gauge go over half when the coolant is bullbing? if so then your car might have overheated and the head gasket might be blown. Next time you drive for an extended period of time, keep an eye on the temperature gausge.To See if it's your headgasket going bad, do this.When the car is cold, open the radiator cap and turn on the car. If radiator fluid shoots out then your head gasket is bad. As well, you will find oil in the coolant, which would also show a bad head gasket.

2. Sometime you've been driving for a while and it's warm, check the lower radiator hose when you turn it off. The top hose should be almost too hot to touch, and the bottom one (it leads ino the thermostat, consult a chiltons or fsm). The bottom one shouldn't be as hot, however you should feel some warmth. If it isn't warm, then it's most likely your radiator (thats what my problem ended up being after hours of work and replacing parts). If it's not the radiator, proceed to the next possibility.

3. Fans - is the fan attached to the belts running? What about the fan attached to the radiator? This is the A/C fan, it also goes on to help cool the temperature. This could well be the problem. See if it is running, if not then you could simply need it replaced. If you cannot see if it is running, then remove the intake, unplug the fans connector (loacted beside the battery, trace the wires from the fan to the connection and run wires from the ends to the battery. If it starts going then you know the fan itself works. Hovever it could not be working, so make sure to check your fuses as well.

4. Hoses/Radiator. Is your car leaking coolant? If your hoses are cracked or the radiator is cracked you will be leaking coolant and losing pressure as well as letting air in. Inspect the radiator with a flashlight as well as the hoses and look for any cracks or signs of coolant.

5. Check your water pump. The water pump is attached to that huge fan that circulates when your car is running. If you look closely, there are 2 small holes in the pump itself, one facing up and one facing down. Check for any signs of water leaking through these. If there is any water leaking, the water pump is bad and will need to be replaced. This is a $40 part and will require only a hours work.

6. If it's not the radiator or Head Gasket or water pump, then you're not in bad shape. I'd reccomment investing $6 in a new radiator cap and another $7 in a new thermostat and installing them. Installing the thermostat is pretty easy, and will give you the chance to refill your coolant. If you want to just text your thermostat,. remove it and put it in some boiling water and see if it opens, you can even test it to see at what temperature it is opening. There is no way i'm aware of to test the radiator cap, find a friend with a 240sx and use theirs, or break down and spend the whopping $6.

7. If you've check all of that and found your problem, you're more than likely going to have to refill and bleed the coolant. To do so, follow these steps properly to ensure all air is out of the system. Air in the system will circulate around and cause the temperature to rise, even blow the headgasket.

Bleed The Air:1. Either jack up the front end or put the car facing up on a hill.2. Start up the car and let it warm up so it's @ operating temperature, PUT THE HEAT ON FULL.3. when it's at operating temperature, open the radiator cap, and loosen the bleeder screw. This screw is located above the intake, it's a 10MM and has some japonese writing beside it. You'll see what im' talking about.4. Open the bleeder screw, and pour 50% coolant 50% water into the radiator cap, and watch as air bubbles pour out of the bleeder screw. Fill the cap as much as you see the fluid coming out.5. Squeeze all of the hoses, push them up and down a bit, but mainly squeeze themto make sure you get all of the air out of them.5. After keep doing this until you get only coolant out of the bleeded screw, no air at all. 6. Close the bleeder screw, top off and close the radiator cap, and you're done!

Hope this helped, i'm gonna see about getting this made into a faq or something, i've never written a 30 minute response before.

Any questions or problems let me know.[email protected]

[DR1FT3R]

WOW!!

edited for content!

[SloS13]

Re: Why is my coolant boiling??

because its HOT.

sorry

FAQ that. I consider myself pretty knowledgeable, but last time I bled the sytem I forgot:

1) to get the front-end up2) run the heat 3) squeeze the hoses

[CanadianCoch]

yeah, I wrote a fricken novel in response to that one. Mods should make it a sticky because I swear it's asked at least once a week in here. I even emailed it to myself so I kept a copy of my first ever novel. lol.

CanadianCoch

[leper421]

when it's at operating temperature, open the radiator cap

Only do this if you want to be a patient at the burn unit at your local hospital. Call 911 and have them send over an ambulance before you start.

[CanadianCoch]

Only do this if you want to be a patient at the burn unit at your local hospital. Call 911 and have them send over an ambulance before you start.

what are you talking about? thats what I've done every time for my and other cars, and it's never sent me to the emergency room

¿ ?

[MrFox]

Guys, you are letting your imagination run away from you.

Read the man's original post

Upon inspection i see that its boiling coolant from the coolant resevior bottle and its waaaay past max and actually bubbling out of the bottle's escape hole. but after its cool the coolant is right at the MIN level.

and oh yea my engine does not overheat.

99% its your radiator cap. The overflow pressure check valve inside your radiator cap is letting pressurised coolant into the resevior bottle. Either you have the wrong cap, a broken cap, or you've overfilled your cooling system.

[bvanev]

Thank you for noticing that...I read the entire Novel too see if our Guiness actually read the question...very basic high school.

[leper421]

what are you talking about? thats what I've done every time for my and other cars, and it's never sent me to the emergency room

¿ ?

How can you take off your radiator cap when the engine is hot with out it spraying boiling fluid everywhere?

[bvanev]

Coolant in the face hurts. The radiator in a ffriends car actually gave out due to excess pressure. He had a custom built radiator and the weld for the radiator cap ruptured, right as I was checking a belt. It hurts like HELL!!! Like a really bad instant sunburn. Be careful working around a hot radiator.

[NISTECH]

if the car is not over heating it could just be a bad radiator cap replace it their cheap.

99% its your radiator cap. The overflow pressure check valve inside your radiator cap is letting pressurised coolant into the resevior bottle. Either you have the wrong cap, a broken cap, or you've overfilled your cooling system.

as stated earlier.

[NISTECH]

Mods should make it a sticky because I swear it's asked at least once a week in here.

Start a thread with your diag and bleed procedures. Correct your spelling errors and reorganize the diag procedures to start with the simple stuff not the head gasket which is the most unlikely cause for over heat on nissans. Possible but not very common. The A/C fan only comes on with the A/C. UNLESS you are already at the overheat point that fan does not cycle on its own to control engine temp.I will reveiw it if it looks good I will sticky it. Dont get me wrong you did cover some good points in your post. just a little mixed up for my taste.

Only do this if you want to be a patient at the burn unit at your local hospital. Call 911 and have them send over an ambulance before you start.

All nissans I have ever worked on dont blow off coolant when pulling the cap. Even after getting off the freeway. when I crack the cap to the release notch it burps a very minimal amount of pressure then the cap comes right off. Unless there is a huge air pocket in the system. that would be the reason for bleeding it properly when its cold to remove the air.

[CanadianCoch]

thats exactly what I was told when my car was doing the exact same thing(100% sure it's the radiator cap), and a radiator cap did not fix the problem. I was trying to give an overall "overheating" sticky, and went over all possible things to check all of his grounds. Last time I checked doing more than I had to wasn't a bad thing. No wonder people bash on the NICO forums all the time. I am sorry for trying to help the man, and ALSO have a good resource to search instead of someome asking this question every week.

Maybe spend some more time helping and less time bashing and this website would get a better reputation.

CanadianCoch

[MrFox]

Water boils at 212F. Coolant around 230F. No car should blow off coolant at normal operating temperatures ~ < 200F.

[NISTECH]

no car should but unless you are able to remove every bit of air from the system it will build pressure and spit coolant at you requardless of the temp of the coolant. the more air the more pressure behind the fluid. ever try to get all the air out of a chevy small block cooling system? you will get sprayed if you pull that cap off at operating temp. for some reason nissan cooling systems are designed to prevent air pockets in the system.

[MrFox]

icic... thanks! learn sth new everyday!

[racin-type]

damn my question got sh*t started umm sorry? anyway i'mma flush the system soon to see if that works (got manual now) if not radiator cap next.

thanks for all the help and advice

[GroundZero]

I read the entire Novel too see if our Guiness actually read the question...very basic high school.

gotta love that microsoft word spell check

[vududoc]

and the smack downs are being issued

[NISTECH]

I appoligize to any one offended by something I said in this thread. no offense was intended.

Scott

[CanadianCoch]

Nistech, you offended no one, you actually had something to say that benefitted anyone, unlike most other posts. Thank you for validating my point about the radiator cap and about the FAQ. I might spend another bit of time and redo that, and apply it as a stick, who knows.

And hopefully that fixed your problem! Sorry 2/3 of your responses were irelevant.

CanadianCoch

[DaveEEE]

Water boils at 212F. Coolant around 230F. No car should blow off coolant at normal operating temperatures ~ < 200F.

Imagine how hot my KA-T was then when I had a blown headgasket... I stopped at the gas station to check it. Even though I *knew* it was hot via my water temp gauge, I took the cap off anyway. It was a coolant shower for the whole gas station. Couldn't find my radiator cap for a few minutes as it launched into the air and into the bushes. Good time had by all... :rolleyes