Civic overheating issues: Grassroots Motorsports forum: Grassroots Motorsports Magazine

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Aug. 21, 2008 1:05 p.m. MadScientistMatt HalfDork

I've got a '95 Civic EX, with a stock drivetrain in it at the moment. It normally runs at a reasonable temperature, with the stock gauge just a tick below the halfway point whether I'm on the freeway or in stop and go traffic.

Yesterday, though, my wife and I got stuck in a traffic jam on I-75 after an hour or so of freeway driving on a hot day. Traffic was at a dead stop, and we'd had the AC on. Coming to this stop made the gauge spike almost to the red zone, and we had to shut it down to prevent overheating. Turning the engine off and the key on and you could see the gauge dropping, and it would also go down if we could go forward even at a crawl. Since getting out of that nightmare, the temperature seems to have returned to normal.

What are your thoughts on this? Did this just overload the cooling system and the temperture spike was normal, or is it likely there's something broken? The incdedent made me think it may be time for a larger fan and better radiator. If I were to upgrade the cooling system, do those cheap all-aluminum radiators you see on eBay actually work better than stock, or would I be better off with a name brand radiator like Fluidyne or Koyo?
Aug. 21, 2008 1:09 p.m. pinchvalve SuperDork

Are you sure the current fan is working? I seem to remember Civic cooling systems to be pretty darn good, and the fan only kicking on under the worst of situations. Perhaps moving has been enough to keep the motor cool, but when it needed the fan and tried to turn it on nothing happened.

The stock cooling system should be plenty, provided everything is working.
Aug. 21, 2008 1:12 p.m. David S. Wallens Editorial Director

Sticking thermostat? The T-stat on my '92 Civic once stuck open. On a related note, we have a really comprehensive cooling system story in the next issue of Classic Motorsports. It's geared toward older cars, but then again a cooling system is a cooling system, right?
Aug. 21, 2008 1:15 p.m. MadScientistMatt HalfDork

Thanks, I'll check the fans and see if they are working correctly first, then look into the thermostat. I hadn't suspected either as it works fine in normal stop and go traffic.
Aug. 21, 2008 2:14 p.m. integraguy Reader

Similar? About 3 or 4 months ago My Integra did nearly the same thing. By keeping it moving after it 1st went into the red I was able to keep it from overheating and damaging the engine. Hondas/Acuras are fairly tough cars, but they do sell better/aftermarket radiators for many models....one of these days I'd like to upgrade so something ike this doesn't happen again.
Aug. 21, 2008 3:12 p.m. MadScientistMatt HalfDork

Fired it up and had it idling in the driveway - it did not overheat then, and the fan did come on when it should.
Aug. 21, 2008 5:00 p.m. poopshovel Dork

Throw a "fail-safe" thermostat in for giggles.
Aug. 21, 2008 6:05 p.m. iceracer Reader

Occasionaly, in stop and go traffic with the AC on the temperature will rise. Especially in high ambient temps and humidity. Turn off the AC and the fan will cool things down.
Aug. 21, 2008 6:17 p.m. MadScientistMatt HalfDork

Iceracer, I switched off the A/C when it started to heat, but still had trouble with runaway temperatures with it off.
Aug. 22, 2008 10:22 a.m. CivicSiRacer New Reader

I'm thinking bad thermostat or maybe bad fan switch. When was the last time you replaced the coolant?

Starting off with the cheapest I would replace the coolant 1st. And make sure it's topped off and free of air bubbles. Then Themorstat since that is next easiest to replace.
Aug. 22, 2008 2:20 p.m. MadScientistMatt HalfDork

I just got it a few months ago, so I never replaced the coolant. I'll probably change both the coolant and the thermostat at the same time.
Aug. 22, 2008 3:23 p.m. Jensenman SuperDork

I'm thinking an air bubble in the cooling system. It doesn't get there by itself, so look real carefully for a leak. The water pump is particularly hard to check, get a mirror and small flashlight and look for the 'weep hole'.
Aug. 22, 2008 9:04 p.m. 924guy HalfDork

weird, but my 98 had similar symptoms. turned out to be the plastic tanks on the rad, check near the fill cap for hairline cracks. new rad was under $100 and 15 minutes worth of work to replace..
Aug. 22, 2008 11:34 p.m. gamby SuperDork

Thermostat is a strong possibility. They start to get grumpy on older cars.

A bubble in the coolant/low coolant can cause a temporary overheating situation. Check that level.

A hole in the radiator would mean it's constantly overheating.

Is the AC compressor working OK? Is it making noise? If it's starting to seize up, the engine has to work harder . This shows up at idle in the form of raised temperatures.

Autozone radiators are aluminum, FWIW.

(yes, I've experienced all of this crap)
Aug. 23, 2008 7:35 a.m. MadScientistMatt HalfDork

It was low on coolant when I got it home - I've since refilled it. At the time, I figured it had boiled over. The A/C has some definite issues which need to be fixed.