theputz

I have been struggling with the same issue for months and now that winter is coming I can’t wait any longer. My 92 civic barely heats up. The gauge moves just a hair (tested the gauge and its fine) and the heater blows warm air but definitely not as warm as it use to. No matter how long I let it run it won’t heat up long enough to let the fan kick in. I also worry because the engine is always cold that the ecu is burning more fuel then needed. I recently replaced the thermostat with an OEM unit two weeks ago, toped up the coolant and bleed the system. No change. A friend tells me that the system is plugged somewhere but if that where the case would the car not over heat? If I touch the coolant hoses after idling for 20+ minutes the top hose is hot and the bottom hose is still cool telling me that the thermostat has yet to open. Correct? What can I do to fix this? I am temped to take the car in to a mechanic and have the system flushed but don’t want to just be wasting money... HELP PLEASE!!!!!

H_Bliss

Two words for ya....HEATER CORE. That should solve your problem.

Former User

Try bleeding the cooling system like this:

1) Park the car on an inclined driveway with the front end higher than the rear.

2) Push the dash heater lever/**** to MAX heat.

3) Follow the directions in the diagram below (hint: the bleed bolt is located where the upper radiator hose connects to the engine):

theputz

why do you say that? What experiences have lead you to this conclusion?

Deetz

Question about your t stat....

did you install it correctly? I've seen this a problem before

civicgsr

This is what I was thinking.

Heater core would only make sense if the engine was able to get to operating temp. Since everything is still cool/cold, I would say that the issue is still at the thermostat.

Air bubbles would lead to overheating or at least the impression that it is overheating. Even then, it's possible for the system to draw in coolant from the overflow to remove the air bubbles. I've had to do that when there was no bleeder available.

1grex

NO

devney

Sounds like a thermostat issue. Check to make sure you installed it right. Or get a new one. Maybe the one you got doesn't work right.

Linked

x2 on the thermostat idea

Former User

While we more often associate air bubbles with overheating, I think you could envision that air trapped in the coolant piping around the ECT sensor and sending unit under the distributor potentially could send incorrectly low temp signals to the ECU and dash temp gauge, respectively. I would also say that this idea predicts that much less air is trapped in the heater core as the heater still works, though a bit less efficiently.

theputz

If the T stat where stuck open would the bottom hose be warm? How could one install the thermostat wrong?

what kind of symptoms would a bad heater core show? I should say that i do get hot air after 15 minutes of driving after the temp gauge moves from the C to the first line (like a millimeter of movement)

v8killaz

try to run the car with no water hoses cconnected or plug them and see if ur car heats up
or check to see if ur tstat is open full chekc it in boiling watter or soemthing

EuroStar Tech

t-stat sounds like the culprit

Jimster480

so even after you start getting hot air your saying the thermostat still doesnt open?

tlarimer

iTrader: (3)

I just went through this on my 93 SI. The car would warm up, but once I started driving the temp would drop and the hot air from the vents dropped in temp too. I replaced the T-stat, it was stuck open, bled the system it worked great for about a day. Then symptoms returned. I pulled the t-stat again, to find that it went bad(stuck open again) Replaced again this time with a 195* (gets to -40/50*here in the winter) and it's been working great. I would say either you have a bad t-stat or installed it wrong. I have put a t-stat in backwards before when I was in a hurry and it would explain symptoms, although I dont know if there is enough room to install backwards with the t-stat housing.

tlarimer

iTrader: (3)

I just went and checked on my spare block, you cannot physically install the t-stat backwards. But you can install it with the nipple not properly oriented in the 12 o'clock position. Which could lead to air being trapped behind the t-stat, and explain your problems.