what is the possibility happen to my engine, (B16A civic hatchback 92) water from radiator always push out to the spare tank till fulls and it will coz my car overheat while driving.
but, when i slow down and during idling, the temp slowly cool down. is it radiator cap or head been bend or blown gasket?

 

Alot of people will say check for oil/coolant mixed for headgasket.
But thats not always the case.
My y8 motor did these same exact symptoms youre having and it was the head gasket.
Its a chance its the Radiator cap. Its the cheapest, so try that first.

 

ok, i try for the radiator cap first...but, is this symptoms for the cap?..

 

I've seen this happen before due to air in the system from not bleeding it properly. If there is too much air in the system and it expands as the car warms up it can push the coolant into the overflow reservoir.

The solution is to fill the system properly. Drain the radiator, move slider all the way to hot on the dash, remove the bolt on the front of the block just to the left of the header (I think its a 18mm or 19mm bolt). Let all the coolant drain out and replace the bolt. Fill the radiator with fluid until its full and start the car. Once the fan has cycled twice the fluid level should drop since it's filling all the empty cavities. Top off the radiator and fill the reservoir to the proper level and you're set.

 

i'd just bought an HONDA radiator cap this morning. parts number is 19045 - PY3 - 013..is that correct parts number?

 

I had the EXACT same problem... and i was in denial about a bad headgasket. But thats exactly what it was! Air from the combustion chamber pushes into the anti-freeze. It got so bad on mine you could actually smell fuel in the antifreeze.

And you have it backwards, your engine overheating is causing the water/air to move into your overflow tank.

Makesure if you change the gasket, to have your head milled and magnafluxed(x-ray pic thingy) of the head. or you will be back too square one in a month or more.

 

it should be a 16 psi cap... idk the art number off hand

 

start the engine with radiator cap off n look for bubbles when its cold

 

i'm so doubtful for my new cap. its in HONDA packing. but on top of the cap, it stick with orange plastic sticker, not an aluminium paper sticker..is it original HONDA?..

 

bump..anybody?

 

From the sounds of it you have a blown headgasket. Generally when the overflow keeps filling it's because the combustion chamber gasses are pushing into the cooling system causing it to fill with air, build too much pressure, and open the radiator cap and fill the overflow. Like others have said though it could also be the cap. Sometimes the caps fill and will not hold to the correct pressure. IIRC the stock pressure is 16 PSI. I'd say just put the cap you bought on it and try it. If it fixes the problem then it's the correct cap. If not, you either have the wrong cap or blown headgasket.

 

is this ok?

 

That doesn't sound like an OEM cap. IIRC, the OEM cap is aluminum with a red and white sticker on top of it.

 

ermmm...any sample pic of it?..
just installed the cap just now...still on run test...if everyhting is ok within a week, its confirm my cap been worns out