So I had drain/flushed/refilled my cooling system and replaced my thermostat, because my civic was overheating. During the test drive, after flushing my cooling system and replacing the thermostat the overheating went away. But as soon as I got home coolant was dripping/leaking out of the thermostat housing.

Should I put a sealant/gasket? Help would definitely be appreciated.

 

There should be a rubber ring that you put around the thermostat before you put it in. Did you install that?

 

Yeah I did.

 

Take it apart again and check the rubber seal position. You may need to try another rubber seal if it still leaks.

 

The rubber seal is not reuseable, and very prone to getting caught and damaged, even with a brand new one. Personally I hate the angle the housing is at as it is extremely difficult to get everthing into place, and then trying to fasten the bolts.

 

you might have smashed the gasket when you put it in did you over tighten it?

 

Red-bull-1, that drawing above that shows a bleeder bolt is not from a Civic, right? I only found a bleeder bolt on the thermostat housing on some Accords and Preludes. Folks often ask here about bleeding their Civic's cooling system, so maybe some clarification is needed. My owner's manual, FS manual and www.bkhondaparts.com show the 01-05 Civic to have no bleeder bolt anywhere. Instead, per the steps in the manuals, bleeding is accomplished by letting air bubble up through the radiator filler neck.

 

If memory serves, folks here and/or elsewhere have reported that the Civics without a bleeder bolt do not purge very well using the manual's method. (My 03 Civic is not due for many more miles or three more years, so I cannot give eyewitness testimony on this point just yet for this generation. But I am watching the posts on the subject for future reference.)

 

its also good to wet send the surface before installing the new gasket. nothing major, just give it a shine.

 

Hello guys ive been having the same problem housing leak so i discovered a design flaw on thermostat housing. if you take it out and put it on a flat surface the two holes where the bolts go through swing back and forth when you press on them. so no matter how new the gasket is or how tight the bolts are..its not flat. the housing is warped due to old age and excessive heat. an easy fix so i used a power sander to grind it flat again. then it it will not swing.