as the title says, it has happened twice now that i'll notice my car overheating when it is sitting at idle for a long time, so ill turn it off and then the fan comes on...i dont think the fan comes on while i'm at idle. either that or i will turn on the a/c in order for one of the fans to come on and i'll drive for a little to get air into the radiator. later i will check my coolant level and i notice that it's all gone. what's wrong?

 

You have a coolant leak somewhere and air is getting into the system and causing it to overheat. Could be a seal, headgasket, crack....you're just going to have to check it out.

 

im not very mechanically inclined, so is there anywhere i should start?

 

Look around your radiator, all hoses, all over the engine block and the firewall where the heater hoses are...if it's really bad it might drip down to the ground under the car. Check out the oveflow tank, intake manifold (some sensors have coolant lines) and if you really don't see anything wet, it's probably a gasket like an intake manifold gasket or headgasket.

 

lay a quite big piece of cartoon under the car and watch for drops of coolant on it...
if there are not any- pull your spark plugs and check for a white residue on their electrodes.

 

i jus did somewhat of a leak down test... the engine was cold, and being that i had no coolant or water in the resevior, i filled it up with water. then i took the cap off and started the car up and let it heat up. i didnt see any bubbles or anything in the radiator. neither did it overflow. however, even after the engine temp said it was normal for about 5 minutes, the fans still did not come on. i dont really notice anything leaking down to the bottom of the car, but i kno that the water i just put in will be gone soon. what now? i plan on doing a compression test soon as well...

 

Ehhh...you had the cap off and no water came out after the car heated up?

That is not good...you need to bleed the system the right way and try it again.

 

u mean no water overflowed out id the radiator? i thought it wasn't supposed to and it was bad if it came out. all that i saw was that there was some steam comin off after it was heated up

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95hprelude &raquo;</TD></TR><TR><TD CLASS="quote">u mean no water overflowed out id the radiator? i thought it wasn't supposed to and it was bad if it came out. all that i saw was that there was some steam comin off after it was heated up</TD></TR></TABLE>

That's how a cooling system works. The water heats up and expands and flows out in to the overflow tank....that's why it's called an overflow tank. Then when the engine cools it sucks that overflowed coolant back into the engine. If you let the car warm up completely the coolant should definately spill out of the radiator if the cap is off.

 

i'll bleed it again and then start it up w/o the cap to see if there are any bubbles.

just to make sure..this is the right way to bleed it right?
1 - loosen the bleeder nut
2 - pour coolant/water into the radiator.
3 - continue to pour in fluid until all of the air bubbles are finished coming out and you get a steady stream of fluid.
4 - once you get a steady stream of fluid, you tighten the bleeder nut.

please correct if that's wrong

btw thanks for your help

 

Yeah, once you get a steady stream out of that bleeder nut your good. Another thing I do is before I start the car I squeeze the hoses with the cap off of the radiator and you can get a lot of the air out that way.

 

How old is your water pump?

 

IMO - when bleeding if you use the stock bleeder valve you should jack up the rar of the car 6 inches or so. This forces the air to that point If you are bleeding it through the radiator cap, jack up the front of the car as high as possible. And I suggest you do it both ways, fust to be sure it all comes out.

I also do the hose squeeze method. It helps to push the air out as well.

 

thanks for the help guys...btw, i do this while the car is off and cold right? also im supposed to squeeze the hose before i pour fluid into the radiator right?

and then after i do the last step (tightening the bleed screw) then i start the car up with the cap off right? and i watch the fluid in the radiator as the engine warms up for bubbles and overflowing right?

also---
bubbles = i have a bad head gasket
overflowing = cooling system operating normal?

water pump was changed with my t-belt i believe, about 20k miles ago

 

Fire the car up. Add coolant/water mixture. Squeeze the top radiator hose ( dont really squeeze it all that hard or you will launch water out of the rad. ) Tap the hose some, give it some light squeezes. Squeeze the bottom one if you wish. I suggest starting this process with a cold car, otherwise hot hoses dont feel to great. Keep filling with coolant/water mixture until it is at the top of the rad and you see no bubbles. May as well losen the bleeder screw at this time to double check. Throw the cap on and check it out.


You may have poped a fuse for your cooling fan switch as well, or its shorted somewhere.

 

does bubbles in the radiator mean that i have a bad head gasket?

 

^^^^^NO

 

it bubbling means its getting air out of the system. why not fill the system completely full and drive around and check fluid levels periodically through the day to see if its a coolant leak somewhere since you cant find ne dripping, that way we can eliminate that option if its the case. like in my situation i have overheating as well at idle but its due to the fan not coming on (i believe lol)

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by M2B4 &raquo;</TD></TR><TR><TD CLASS="quote">i have overheating as well at idle but its due to the fan not coming on (i believe lol)</TD></TR></TABLE>

i think thats my problem as well. it never has the problem while i'm driving for a long time. i went on four 4+ hour trips in the last two weeks without any overheating problems. only i also notice fluid from the resevior constantly disappearing

 

yeah my overflow tank has always been low because i never seem to have coolant to fill it with lol plus its never overheated driving but ive sat and tested my fan for like 20-30 mins letting it idle no fan comes on and ive driven friends cars where you can hear the fan kick on at idle but not mine, and like you said ive driven hrs also and never had ne cooling issues. only at idle like in long drive thrus itll heat up but i just turn my heater on full blast.

 

yea only thing is that my overflow tank gets bone dry after a while.

also ive heard that a/c makes ur car overheat from many, but not mine...after testing the a/c, i noticed that the fan comes on with the a/c...so when im sitting and i see the temp gauge go up, i actually turned on my a/c once and started driving and it went right back down to normal

 

well if ur tank gets bone dry then you must have a small leak somewhere. top it off and idle it for a while and see if it overheats (with a full tank). well my ac dont work so i just put the heater on b/c it pulls some the heat from the motor and if the heater doesnt cool it down enuf i just leave the drive thru and drive to "air dry" the motor lol

 

sorry to bring this back...

update: i used bar's stop leak for the radiator (i found the leak in the radiator) and topped off the radiator and overflow tank to the max and bled the system and i'm not noticing any more overheating at idle (after about 10-15 min). however i did see the overflow tank level go down about a 1/2 in from the max line.

also today i pulled my plugs to check them out. do they look fine to you? also how can i tell if i need a new head gasket or not? do the condition of plugs tell me whether or not i'm free of that problem?