Problem:

So my 99 Civic has been overheating every so often. The overflow reservoir has been overflowing itself with coolant rather than circulating back to the radiator. The upper and lower hoses become very stiff with pressure after running it for a while. The other day I ran the AC for a little while and that caused it to heat up.

What I've replaced:

-Radiator & radiator cap
-Reservoir & reservoir cap
-Upper and lower radiator hoses (original upper hose had ballooned and split)
-Thermostat

I've pressure tested it and combustion leak tested it.. both came out fine. I've checked the spark plug housing and there is no leak there. I've bled the coolant several times as well. No typical signs of a blown head gasket. I haven't replaced the water pump which may be the problem? Could it be just a small leak from the head gasket?

Help appreciated!

 

The only time I have had a bad water pump it has always weeped from the weep hole (drops at a time) the only times that I had the overflow overflowing has been when I had poor coolant circulation due to clogged radiator and the other was from blown head gasket.
I assume you felt both hoses and they both were hot.(thus thermostat working properly)So you say you did a compression test on the cylinders? What were your readings

 

ok the first time it overheated, what was the cause. no water, no oil...
hondas are really sensative when they over heat. i went through and replace everything and it was the headgasket the whole time.

 

The readings were normal according to the directions. I couldn't tell you exactly what they were because I did this a few weeks ago, but they were in the appropriate range. The leak test was normal as well.

 

No coolant. The radiator cap was garbage and wasn't controlling pressure.

 

One other thing. When I haven't started the car for a few hours and turn it on again, I get a loud screech. Not sure if it's the timing belt or the alternator belt. If that even relates to the problem whatsoever..

 

have you checked if your radiator fan kicks on?? check the fuses for the radiator cooling fan as well.

 

I also experienced overheating. instead of water, coolant should always fill.