My car (95 civic, turbo d16z6) started overheating recently. I've noticed that when it happens, it's because it blows all the coolant into the overflow tank (which overflows ) and then will start to overheat when parked. For some reason, even at this point, it will only start to overheat at idle, standing still. The fan won't even attempt to come on as it's overheating, which I also find to be funny. Now, what I have to do is go under my hood, and dump (almost) all of the contents of the overflow tank back into the radiator, and then the temp goes back to normal and she acts fine for another few days.

Then the process repeats itself. I am getting really pissed off trying to diagnose this, as it just doesn't make sense to me why it only happens sometimes... and why it keeps blowing into the overflow... And lastly, isn't it supposed to suck fluid back into the system from the overflow when it's low??? I'm stumped...

Lastly, I just changed my oil yesterday. The oil was normal colored, no coolant, and the coolant (though begining to get dirty from being poured back so many times) is still green, absent of any oil as far as I can tell.

Somebody give me some insight!

 

Do you have a aftermarket radiator cap? If so change it. Sometimes the spring goes bad in on them....it happend to me. Dam SPOON...lol

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">The fan won't even attempt to come on as it's overheating</TD></TR></TABLE>

thats bad... make sure your thermoswitch (it tells your fan when to go on)didnt go bad. the fan should be on trying to cool down your radiator at idle.

check your thermostat, radiator cap like said above, radiator fan... just for starters.

i hope you didnt warp your head

 

It is very very likely you have a leaking head gasket. I have had those exact same symptoms on two different engines and both were leaking head gaskets. you can go to a local shop and they will check for hydrocarbons in the coolant system or you can buy a block tester from napa that will test for hydrocarbons in the coolant.

basically i'm 90% sure this is your problem. the first engine that started doing this to me i spent tons of time swapping parts, radiator cap, fan switch, thermostat, but eventually got it tested and figured it out.

 

I had the same problem you were having, then I blew the coolant bypass hose on the highway and after I replaced it everything has been fine.

so you're loosing coolant somewhere, whether it bee the headgasket or a hose etc.

funny thing is, my car didn't leak a noticeable amount of coolant, guess it evaporated before I saw it.


get a leakdown test and carbon test for the coolant and go from there.

 

if it overflows to the resouvir tank then it's the headgasket.

 

Yeah, my guess is headgasket too. I've had similar problems. Check your exhaust smoke. Is it white?

It can also be the thermostat. We used the same one after the headgasket install and then a week later my mom called "the car just over heated." **** I got scared, i thought that headgasket install was flawless. Then i remembered the thermostat Sent the old man up to fix it, and haven't had a problem since. Has been a year

Man that headgasket sucked. That was the 2nd van I replace the headgasket on for my parents.

 

same thing here too...


turned out the head studs were not torqued down enough (actually only to aboue 30 ft/lbs ) and air got in the system, rad fan never came on.


Check compression/leakdown. I bet its the gasket or the studs, or maybe even a cracked wall

 

well, dont' have a compression or leakdown tester. It does all blow into the overflow tank.

I'm going to work from simple --&gt; expensive I guess. I'll start with a radiator cap (right now, I think) and work to a headgasket. As a matter of fact, though, my car does smoke a little white... well, a little of everything. She burns some oil, runs rich, and who knows -- but I don't LOSE coolant, it just goes into the overflow.

I guess when there is no pressure in the system, the radiator fan disables itself (or the temp sensor never even gets hot...?)

It works fine / normal (fan and all) once I pour the contents of the overflow back into the radiator~!

Thanks for all your help guys. I want to test this coolant, too, like some of you said. Where can i get this kit?!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">I guess when there is no pressure in the system, the radiator fan disables itself (or the temp sensor never even gets hot...?)</TD></TR></TABLE>

Interesting theory. The fan doesnt go on because air is occupying the space that coolant should be, and therefor doesnt carry the same temperature of the coolant. Air from a leaky headgasket or head studs will seep into the cooling system and push the coolant out into reservoir. Also, if air is in the system it might not get the thermostat hot enough to open fully...

A compression tester can be found for like 30 bucks at the parts store, and if you wanted you could even convert it into a leakdown tester

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18EG6 &raquo;</TD></TR><TR><TD CLASS="quote">
A compression tester can be found for like 30 bucks at the parts store, and if you wanted you could even convert it into a leakdown tester </TD></TR></TABLE>

how do i do that?

 

to bring an old thread to the top, the whole problem was the result of an old/faulty radiator cap. $7.99@ autozone and she's back to normal.... go figure.
Glad that's over with

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Johnyquest &raquo;</TD></TR><TR><TD CLASS="quote">to bring an old thread to the top, the whole problem was the result of an old/faulty radiator cap. $7.99@ autozone and she's back to normal.... go figure.
Glad that's over with </TD></TR></TABLE>

Sweet! That's great to hear. Glad the problem wasn't too serious after all.

 

wow . . i had the same problem with the radiator overflowing into teh resevoir and i changed the cap and it didn't really solve anything . . . laters i found that the radiator started to split between the plastic and the copper . . . and just bought an all aluminum radiator w/ a high pressure cap and it seemed to solve everything . . . i didn't touch the head gasket or even the thermo really . . . might keep an eye out on the radiator . . .

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ekb18c &raquo;</TD></TR><TR><TD CLASS="quote">if it overflows to the resouvir tank then it's the headgasket. </TD></TR></TABLE>
on my Yota, I sent the overflow across the yard, following a 30yd stream of coolant after the HONDA radiator(yota threw a water pump, sending the fan into the stock radiator, and well, being a honda guy, ive got bunches of radiators laying around)
over flow nipple thing literally BLEW off from the pressure.
WHen the water pump went, she kept driving till it just died. I havent had time to open up the engine yet, but Im betting a nasty cracked head, and dont even bother w/the HG

The engine runs GREAT w/out any coolant in it just as long as its not for over a few seconds...