Hi guys,

I have a 1993 civic dx. At one point, I was losing coolant, so I took the cheap road and tried some brand of stop-leak. (insert your own you're-a-dumbass-remark here)

Anyway, I ended up replacing the water pump. Now I have less than stellar heat, which is somewhat important in the northeast. I thought maybe the stop-leak stuff plugged my heater core, so I removed the hoses at the firewall, and using a garden hose, flushed it out, and then did it in reverse as well. The water flowed clear and strong, I put it back together, and the end result was slightly better, but still not good, heat. I repeated this 2-3 more times with no significant improvement.

The heater control is in place and functional (and not clogged), the engine still warms to the same temp as it did before (I changed the thermostat) and the blower fan works fine. Coolant level is also fine.

Sooooooo, did I foul up my heater core permanently? How tough of a job is this? I found the blower motor, and I suppose the core is nearby, but I don't want to tear the dash apart.

If I missed anything, let me know.

Jim

 

Check coolant level directly in the radiator (engine cold). It is possible for the level in the bottle to be OK but the radiator low. The radiator should stay full to the top at all times.

You need to take the dash out to replace the heater core. It's not as hard as it might sound though. But if water flows through it readily and it doesn't leak, it should be OK.

Check the linkage on the bottom of the heater box that controls the air door. The air door should move all the way with the lever on hot, also the other cable that goes through the firewall to the water valve should move all the way and open the valve wide open. Both heater hoses should get hot with the engine warmed up and the heater on.

 

Also try bleeding the cooling system, which may take 20-30 minutes:

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):

 

I shall try the bleeding.

Thank you very much.

Jim

 

As mk mentioned, be sure also to check whether the heater hose valve located on the firewall is fully opening and closing properly.