i have a 91' civic w/D15b swap and boomslang harness from DPFI to MPFI then VTEC'ed. my question is that i CAN'T get the fan to come on when the motor heats up to it's normal operating temp.. the fan switch for the OBD0 is on the back of the block,NOW,could i just take the 2 wires from the OBD0 harness,that was located on the back and run them to the thermostat housing where the D15b is located at? the motor wants to OVERHEAT after i replaced water pump,thermostat,just CAN'T get the fan to come on properly..............ANY info to try something would help!

 

Info!

 

That's what you are supposed to do. so it only overheats if you're not moving right. it should get adequate cooling while driving even without the fan on, so if its overheating while cruising down the street at 35 mph, then you've got larger issues to address.

 

^^ X2

If those wires from the back of the motor are not hooked up to anything then your fan will NEVER turn on.
They hook up to a temperature controlled switch - fan switch.

Before you reroute them to the switch on the thermostat housing, short them together and turn the car on.
The fan should run constantly.
If it doesn't then you will need to troubleshoot wiring, relay, or fan motor.

 

well,the car never overheated with the old motor,so i'm guessing it should'nt do it now. and the fan works and it's an uncut OBD0 engine harness. now i DID NOT check possibly a fuse or relay,but when i jumped the 2 wires on the harness and turn the key on,the fan DOES'NT come on..................

 

anymore INFO guys?

 

unplug the connecor on the fan and hook the fan up directly to the battery. I doesn't matter which wire goes where - it will spin one way or the other. That will tell you if your fan motor is fried or not.

 

figured out some of it,................the fuse was blown,should looked at that 1st before pulling my hair out. but,the fan still DOES'NT come on,still wanting to overheat.............uuggghhhhh!

 

What happens now when you jumper the wires together and turn on the ignition?
If it still doesn't come on, try hooking the fan direct to battery.

 

Just curious but as D16 asked does it overheat while moving? If not then make the fan work and you will probably be fine. If you really cant get it to work off the temp swith then just wire it to a switch and manually turn it on oh well. If the fan works and it still overheats check your timing and make sure you arent to advanced as that will cause you to overheat,

 

i'm going to try the jumpering of the 2 wires today,now that the fuse is good! the fan DOES work when i put it to a 12v source and while driving,it still trying to OVERHEAT. is it possible that the coolant hoses that are coming from the firewall may be routing to a different spot on the side of the head and the thermostat housing on the D15b..................good ? huh? BTW big THANKS for the INFO guys

 

If it's trying to overheat with the fan constantly on then it could be a few different things.
When exactly does it try to overheat? - idling at stops, while cruising along, etc?
Do you have a thermostat installed?

So you say that you can jump the fan to the battery and it works? GREAT!
That's good news! check those 2 wires out on the back of the block and you'll be 1/2 way done (or more) troubleshooting this thing.
If the fan DOES come on with the wires jumped together, then extend them and hook them up on the temp switch on the thermostat housing, warm the car up, and cross your fingers. That should fix your fan problem.

 

did you properly bleed your cooling system? that can cause symptoms of over heating

 

thanks guys,i got it to work properly....................!

 

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