Got a (currently) stock '95 Civic EX. The temperature normally stays just a tick below the halfway mark on the gauge, even when in stop and go traffic. Yesterday, though, I ran into something that pushed the cooling system over the edge.

The car had been running down the freeway for a couple hours when we came upon a traffic jam with all lanes blocked and had to come to a dead stop. The temperature gauge spiked almost to the red zone and I got a smell of antifreeze. It could come back down if the car got moving, even a little bit, but sitting nearly still for over an hour in that heat could provoke the gauge to spike enough that we had to shut the car down a couple times. It hasn't shown any heat issues since getting out of that traffic jam - yet.

Is this a symptom of something that needs to be fixed, or did the combination of blistering heat, a lot of heat buildup, and sitting still just overwhelm the stock cooling capacity? Also, if I upgrade the stock cooling system, are those cheap all-aluminum radiators from China actually an upgrade or worse than stock?

 

Update - confirmed it definitely isn't a fan issue, as the fan turns on while idling with the car stopped. (Then again, it also didn't overheat - I haven't been able to make it overheat again either.)

 

Is the fan blowing with strength? I had both my A/C condensor fan and engine fan die within years arpart. They still spun, but kept getting weaker and weaker till the point where it barely moved any air.

 

Have you replaced the thermostat?

Is your coolant a 50/50 GREEN mix?

If you smell coolant, you have a leak, you'll need to find it and fix it.

That should be all you need to solve the problem.

 

Thanks everyone... here's some answers.

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Interesting possibility. The way even getting up to 5 mph could get it back down does suggest an airflow problem. The fan sure does make a lot of noise (and not in a squeaky bearing way) but I didn't check airflow rates.

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Not yet, it only happened yesterday and normally the temperature readings are a bit more resonable. I'll need to take a look at this.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Is your coolant a 50/50 GREEN mix?</TD></TR></TABLE>

I'll need to get a hygrometer and check the mixture as I've only had this car a couple months and haven't changed its coolant yet.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">If you smell coolant, you have a leak, you'll need to find it and fix it.</TD></TR></TABLE>

The leak seemed to be in the overflow tubing, not the regular cooling system, and it was definitely boiling over.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MadScientistMatt &raquo;</TD></TR><TR><TD CLASS="quote">Got a (currently) stock '95 Civic EX. The temperature normally stays just a tick below the halfway mark on the gauge, even when in stop and go traffic.</TD></TR></TABLE>

Thats pretty much how any honda temp gauge works, they come up to just under half way, and essentially they don't move until the engines pretty much hot enough to melt.

 

It could have deposits built up on the inside (usually calcium) that could affect cooling capabilities. It couldnt hurt to get one of the ebay jobbies, they seem to be ok, just dont use the caps that come with them they are junk. also if you get one flush it out well, they are full of aluminum shaving you dont want in your motor. also after an overheat you should replace the thermostat, I would only use a honda one for that

 

Thermostats fail without warning, if you haven't replaced it, I would suggest doing so. That 15 dollar part can ruin your day, or month... or engine?

Unless you have huge buildups in your bumper, airflow shouldn't be a problem. The rad fan practically never comes on. Even at idle, with all the Honda's I bleed everyday, it takes at least 10 minutes after driving it for the fan to turn on.

The temp gauge stays in one spot because the thermostat will respond to the engine temperature. If the needle fluctuates at all, even if its not overheating, its a sign of a bad wax pellet in the thermostat, replace it.

Do not replace the radiator until you know what is causing the problem. Replacing the radiator does nothing, even a slightly modified engine can run on the stock unit. The thermostat will just allow more coolant to pass. In a way, its like setting your timing without jumping the SCS connector, pointless.

Do your radiator hoses feel stiff when fully warm? If not replace the cap, you have no pressure which will cause the coolant to boil in the engine, spiking the gauge.

If your lower rad hose is very cool this will also indicate a stuck thermostat, which will not allow the cold coolant into the engine. It should be fairly warm, but not as hot as the upper.

The Honda thermostats like to **** themselves to the side and get stuck, just a note of the some 100 I've replaced.

Deposits will harm cooling, but they don't appear overnight. Hell even the Dex-Cool sludge still manages to dissipate heat.