It's winter here and have had nothing but problems with my 96 ex lately. Car is bone stock and refuses to get hot enough for my heater to blow hot air.

My car will idle up to temp sometimes, but as soon as I start driving the temp drops almost to the bottom line again. The lower hose will stay cold after a 30 minute drive. flushed the radiator, flushed the heater core, replaced the thermostat 3 times with 3 different brands, replaced the radiator cap....idk where to go. When I have my scanner hooked up to the obd2 the temp never gets past 160 unless it idles for and ungodly amount of time. Any ideas?

 

Did you bleed the cooling system?

https://honda-tech.com/honda-civic-d.../#post39830585

 

I have bled the system once or twice a week thinking that's it. I raise the front with the Jack a little, take the cap off, and let her run. But the problem is, the motor never gets hot enough that the thermostat opens.

 

This might seem like a long shot (it probably is), but is your gas mileage abysmally horrible? Check your fuel pressure. If it's too high, could wash the cylinders down and lower combustion temperatures. I doubt it'd lower them THAT much, but you never know.

 

Was the heater set to max heat?

 

change your thermostat... 100% sure.

 

He already did 3 times.

 

oups... really weird... cause that's exactly the symptoms of a "ever-open" thermostat, or no thermostat at all...

so ok with RonJ@HT, maybe not the max heat on the heater...

 

Just for fun, put a piece of cardboard in front of your radiator with a 5 inch diameter hole cut in the middle of it.

Does that prevent the car from going cold when driving?

 

Does your fan turn when the water is cold? Or only at 90'??

 

Yes, when the system was bled the heat was all the way hot as well as the blower on the highest setting. Fan worked fine this summer when the motor got up to temp, car has not overheated since last summer when I replaced the headgasket and all the rest of the cooling system. Just when this cold weather hit, it decided it just doesnt want to warm up.

Originally had a stant thermostat in it, a cold day hit, the car never warmed up so I replaced it with a failsafe. Was warm another week or two and never had a problem, now its starting to be consistently cold and the problem still existed, so I replaced it again with a duralast one from autozone. Problem is still on full, car will get up to temp and stay there if I have the heater control valve closed. I open it, it will be fine for a few, I turn the blower motor on and the temp just drops to almost rock bottom.

 

Goto honda and get an OEM one even though it's more expensive.

All 3 are 3rd party thermostats. Thermostats is one of the parts that is always recommended to be OEM.

 

I agree that. Your problem comes from your thermostat.

 

What is your coolant mixture? 50/50 is proper. To much water will run cooler and obviously risk freezing on cold nights

Also is your fan switch operating too soon making the fan run longer or more often than normal

 

I don't want to muddy the waters, but I always see people saying that non-OEM thermostats are junk, yet I have never put an OEM thermostat in my many hondas when replacing it, and I have not once had a problem with them. I've probably replaced 10-15 thermostats over the years with non-OEM ones and they have always been fine.

The fan switch and the cardboard in front of the radiator were both good ideas to try.

 

Post the specs of these^ thermostats. How do the specs compare to those of OEM in the table below.



How do you know whether or not the thermostat opens?

 

I didn't see if the OP mentioned if his radiator cooling fan is coming on properly,or staying on.If that fan is coming on,and staying on too long, I think when the interior heater fan runs,it will cool down the temperature too much.Worth looking into.

 

The lower hose is cold, it never even gets luke warm. I have very high doubts that the thermostat is opening. Maybe my understanding on how the cooling system works is wrong, idk....but I will call my dealer Monday and order an oem thermostat, it wasnt that I was too cheap to buy one, it was a convenience factor to buy one at a local parts store. I will replace that when it comes in and report back.

 

Finally got around to putting in my oem thermostat, so far so good, took a good long time for it to burp since its 20deg out....I thank you all for the help.

 

Happy you find your problem!
That could only be the thermostat or the bleeding...

 

Hopefully it was a thermostat from the Honda dealership and not an oem aftermarket brand. Because some members still don't recognized the difference between oem quality and aftermarket oem, therefore they still consider them 'oem' regardless.

 

Glad your Honda Thermostat fixed the problem.

Yeah definitely takes forever to burp when it gets chilly out.

Cheers

 

It was in fact an OEM Honda replacement thermostat and gasket from the dealer

 

Good choice.