jax93

Hey everyone I need help resolving a cooling system problem. I have a 93 honda civic Si with a d16z6. 3 weeks ago my temp guage started to raise to half way point at a red light. I made it home without getting it above the half way mark. I changed the thermostat (duralast brand). After changing the thermostat I flushed the cooling system and replaced it with new coolant. I did bleed the air out (placing the the heat on full blast and waiting for the fan to kick on) and filled the rad with coolant as it dropped til I didnt need to add anymore and fyi it took my car 70 minutes for the fan to turn on. I read other threads and other civics took 20-30 minutes to turn on. I also replaced the rad cap with a new cap (duralast). My car ran great til about 5 days after my temp guage started to raise again, this time it went a little above the half way mark. I checked the fan by hard wiring it to the battery and it turned on. I checked the relay by using a paper clip connected to the thermoswitch sensor connection and the fan turned on. I replaced the thermoswitch with a used one and bled the system of air. I didnt wait for the fan to turn on because i needed to get to work ontime. the car did not overheat of go past the regular operating temp til 3 days after changing the thermoswitch. this time it was about an eighth past the half way mark. My reservoir overflowed with coolant making a mess in the engine bay. the weird thing was when i was driving, the temp guage dropped to regular operating temps and at stop signs and red lights it jump back up above the half way mark. I replaced it with a new switch (valucraft from autozone), opened the bleed valve to get air out of the system, closed it and waited for the fan to kick on. the fan never kicked on after about 45 minutes. I took it out for a spin and it didnt over heat or lose coolant. I drove for about 20 minutes going no more than 50mph. I just drove it to work and back home and smelt coolant so i popped my hood and found coolant everywhere. It was leaking from the rad cap. Do i need to bleed the system of air again waiting for the fan to turn on?? Does having air in the system create pressure causing coolant to overflow the resveroir and leak from the rad cap? any help is appreciated and i know using a used switch was dumb haha. thanks for any help.

civic402lx

Buy OEM t-stat and radiator cap. Auto part store cap are known to leak.
replace both of those and rebleed the coolant. Turn the temp diual to full hot, do not turn the blower fan on. Just leave it off. Raise the front end of the vehicle up.
Start the car with radiator cap off. Run it til the cooling fan kick on, continue to refill coolant til no more bubble(air) come out the radiator. Wait til the cooling fan kick on the 2nd time, watch the coolant level in the radiator. Fill as needed. If no more bubble come up. Put radiator cap back on, fill up coolant reservoir to max line. Lower the car, go for a drive.

That is how I bleed the coolant on my civic with gsr motor. Never had any overheating issue..

Get those auto part store parts out of the engine, get OEM cap and t-stat.

jax93

civic402lx thanks for the help. I bought what you suggested and replaced the switch. burped the cooling system waiting for the fan to turn on twice. it actually turned on this time! way quicker than i excepted. i waited for the fan to switch on 3x to be safe. the switch(duralast) i bought from autozone was faulty so i threw it away. Sh*tty part about this whole thing is i bent the top of the rad. I ducted taped the funnel to get a tighter fit but when i pushed the funnel into the rad i bent it a little so now it leaks at the top of the rad. hah! lesson learned. I appreciate the help civic420!

chrysler kid

Auto zone rents the coolant pressure test kit , you will need the import radiator cap adapter as well. You basically pump up the pressure tester and verify that it holds 15 psi. If it doesn't hold pressure your cooing system has a leak