dansf100

I just got done finally getting my '90 Civic with a D16A6 to stop overheating, and I'm wanting to share my story to help others who may run into the same problem. I bought this Civic just a few months ago and it had an overheating problem. It would be fine at freeway speeds and some light around town driving, but as soon as it got into heavy stop and go traffic, the temp started to spike. I tried a new Thermostat and gasket thinking that maybe it was stuck. I even pulled out the old radiator and flushed it with a hose and high pressure water every which way I could. Still overheating. Took a gamble on a new water pump thinking maybe it was partially faulty. I even replaced both temp sending units in order to solve a different problem I was having with a rough idle. Eventually, in an unrelated turn of events, I broke an exhaust valve and had to pull the head. New valve, new head gasket, new head bolts. Got it all together and what do you know it's running great, except it still overheats. I did the prescribed bleeding procedure to the letter many times and still no cure. I even went so far as to put a new radiator in today, then bled the system......still overheating.
Finally, tonight, I found a site online that talks about a Honda Tech Bulletin for overheating Civics. Here's the info they give.

Purging Air From The Cooling System On
Honda Civic Engines

AERA members have reported engine overheating and inoperative cooling fans on Honda Civic automobiles after cylinder head or engine service.

On these automobiles, it is possible for air to become trapped in the intake manifold or cylinder head when the cooling system is refilled. Coolant may not circulate to the sensor portion of the thermostat, resulting in cooling fans not working.

Eliminate air pockets by bleeding the cooling system:

1) Refill the cooling system and raise the right front corner of the automobile with
a suitable jack.
2) Set the heater temperature selector to maximum and leave the blower fan off.
3) With the radiator cap off, start the engine.
4) When the engine reaches normal operating temperatures, open the air bleed
screw until coolant flows in a steady stream. Wear protective gloves to
prevent burns from hot coolant.
5) Lower the car and fill the radiator and the coolant reservoir. Close the cooling
system and verify that the cooling fan works on schedule.

The AERA Technical Committee

So, I ran the front end up onto some ramps about 10 or so inches high. Then I took out my floor jack and some wood blocks and lifted the drivers front corner up another 12 inches or so. Then I followed their instructions, and finally, the overheating problem is gone.
Anybody else out there have an overheating issue, give this a shot. Nothing else could solve the problem. Thank you internet.

efjones9

Nice . First I've heard of this problem but nice info

sandradf20

My 1997 Civic runs hot within minutes when idling. I just bought this car from a used car dealership. At first it was running hot all the time, I took it to the mechanic the dealership uses and he replaced the thermostat. That fixed it, now it only runs hot when idle but goes all the way up to the red. I put everything I had into the car and I'm terrified that something bad is going to happen. As soon as I take off it goes back within normal range. Is there something I should check. The mechanic said the fans were working but I'm not sure what to do. Thanks for any input.

D16SiHatch

did you check to see if the fan was really turning on?

it is a really bad idea to let your car overheat into the red. don't let it get that hot. head and block are aluminum, that much heat easily can warp them.

AlfieRoach

this should be on the FAQ, any takers?