Hopefully I can get some answers. My car was overheating due to a leaking radiator or so I thought. I took off the thermostat, bought a new water pump & had the radiator fixed. It's still overheating! Tomorrow I'm going to flush out the radiator & see if it helps. I had to run a switch to the fan but it works. Any other ideas what it could be? I've read about a bad radiator cap, loss of coolant or a blown head gasket. I just want to know if their is anything else that could cause this

 

It is possible to have a blockage in the radiator or engine block, but most likely it is a bad head gasket.

 

check your oil. if its milky looking then you got a blown headgasket

 

when does it overheat? while driving or while sitting?

 

It overheats while sitting. It's like 5-15 min's that the needle starts going up after being turned on

 

Whats Mugen about this, am I missing something here? Try properly bleeding the cooling system, these cars take a long time to bleed fully. And it could be the radiator cap or head gasket.

 

sounds like a fan or t-stat issue..

 

What a bummer, I was hoping to see some Mugen goodness! Ha!

Anyway, way to get my attention. JDMDA7 is right, make sure it's bleed properly.

First though, warm the car up, and check for these things:

(1) Feel the lower radiator hose, it should be just as warm (or very close to) the upper hose. If it's not, you have a blockage in the thermostart. You said you removed it. Did you replace it with a new one?

(2) Check your fan polarity. Not sure if you have a front mount (push) or rear mounted (pull) fan. Either way, It should be pushing air THROUGH the radiator, towards the firewall. If it is pushing air the opposite direction, this could cause your car to overheat rather quickly at stop lights, etc... If the fan doesn't come on, you either have a bad fan that needs to be replaced, or...

(3) The thermo sensor at the bottom of the radiator is not connected properly. This is easy to do on a 1G CRX, as the little thermo sensor at the bottom of the radiator just has two little male nipple connectors. It's REAL easy to have your female connectors from the harness connected reversed here, thus causing a read error. It won't sense your coolant being hot enough, and thus will not tell the ECU to kick the fan on.

(4) Lastly, if you have checked all the above, and the fan is coming on, there is still a chance that you have a week ground going to the fan, and even though it is spinning, it is not spinning at an appropriate RPM-level. Check your valve-cover to rad. support brace ground at the front of the engine. This is the main ground that effects the RPM of the radiator fan.

I can't think of anything else, other than low coolant level. Check that as well.

Best of luck!
- Dan T.