Thumper74

I just had a head rebuilt on a 2000 Civic LX with the D16Y7 engine. It purrs like a kitten.

All parts were OEM Honda. I did not replace the thermostat as there was no overheating concern before it jumped time.

It's about 40 degrees out right now.

I put it all back together and while I get GREAT heat, the lower hose is cold. The upper hose is hot, all of the heater hoses are hot. The temp gauge stays half way up. It stays perfectly horizontal (where it was before). It's not overheating per the gauge on the dash.

I drove 3 miles tonight in slow stop and go driving, where I figured it would be more likely to overheat, but no go, it's fine. The fan has not come on, but the condenser fan is coming on as the defrost was set on high per the Service Manual. I'm tempted to just leave it, however I'm nervous that the hot coolant is staying in the water jackets and not going where it needs to be, but the radiator is warm

After searching the forum, the general consensus seems to be that it's fairly normal... However, being that I just reassembled it, I feel I'm being justifiably paranoid.

Which way does the coolant flow through the cooling system? The manual doesn't mention this, but it seems that it flows from the block, thermostat, through the lower hose, up the radiator to the upper hose and back into the block. Is this correct?

I also have a 2000 Accord LX with the 2.3L and can't say that I've noticed that the lower hose is cold, but then I've never checked it.

kp

Googled it and found a thread on HT that explains it back and forth a million times. Here's the link...

https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/direction-does-coolant-flow-434634/

And here's a quote from somebody with 9 years on HT, probably okay to assume he's right...


Makes sense, hot water comes into the top of the rad and as it cools it naturally flows to the bottom where it re-enters the engine nice and cool.