car: 89 crx si
engine: D15b7
miles:rebuilt stock with 9,xxx miles
Radiator: Full Aluminum Fluidyne (the temp guage reads temperature at lower than normal after i installed it)

I believe the car had nothing but water in the coolant system. after a while of driving, the car started to be low on coolant and the temp guage reach a unfamiliar reading. turned the engine off before it reached any further and checked under the hood. looked inside the overflow tank and nothing, removed the cap, nothing. so i added 50/50 antifreeze into the rad and some into the overflow. drove like that for a week or so.
well, engine doesnt over heat. but once it gets to normal operating temp, the overflow tank starts to bubble. the fan doesnt turn on aswell. (mind you that the fan had worked before any of this event).

what could be the symptoms of the bubbling thats happening?
i have changed the radiator cap.
i believe the thermostat is working(lower rad hose gets hot)

What i will be doing is a coolant flush.

*also, i have noticed that in the morning when i start the car, it feels like it misfires but soon after about 4-5secs it goes away and drives fine.

 

Could be air pockets/ air bubbles in your cooling system

 

It is probably bubbling because the coolant is evaporating from over heating. You just need to bleed the system.

Jack the front of the car up just until the neck of the radiator is higher than the thermostat. turn the heater on full heat and fill the radiator but don't fill it too much.

Start the engine and let it warm up with the radiator cap off. when warming up the coolant level will change, it will go up and down from the air escaping and also because the coolant will expand with heat from the motor. Let as much air bubble out as possible well filling the radiator up with coolant so it doesn't get too low or too high. It will most likely over flow when doing this also. when no more air is coming out turn off the engine and let it cool down. put the cap back on and start engine and wait for the fan to click on. If it doesn't turn on after five min or you car starts to over heat start over.

 

any more ideas?

 

It could be an air lock so bleed the system from the bleed valve and as mentioned before add coolant as needed. Next put power to your fan and make sure it is working, second check the wiring on the thermal fan switch, it gets brittle with age and can crack and corrode. Also check continuity of the thermal fan switch with a coule of jumper wires as I found a couple that didn't work at all and a couple of others that didn't open the circuit until the fluid started to boil which is a little late at that stage in the game.

 

the pressure within your cooling system mainly supplied by the radiator cap should be what keeps the boiling temp of your coolant down. if it seems to be boiling too soon it means your cooling system is losing pressure thus increasing the boiling point of your coolant (a leak possibly??--or possibly the fact that your fan is not turning on)

as for your fan you might want to check out the CTS (coolant temp sensor) or jus check wiring /continuity with dmm on the fan to make sure everything is working as it should.

hope that helps.

 

ah, fixed it. jumped the temp sensor and it didnt work, replaced the relay! thanks guys. also bled the system. everything operating as it should! woohoo