Problems

[swest_jefe]

OK, I just did an engine swap and as if I didnt have enough problems, I finally get everything running right, go out on the first test drive out of the driveway and I find out the engine fan isnt kicking on. Ive changed out all the sensors on the thermostat housing, checked the relays and the fuses, but still nothing. There are no trouble codes. Anyone here have any ideas, its pretty damn frusterating to spend a month fixing your broke car, only to find out you cant drive it 2 miles because the stupid engine fan unexplainably wont come on. Im about ready to just hardwire the damn thing to the battery.

[boosting20psi]

if you have checked everything then check it again somthing has to be wrong some where. if not hen just hard wire it like you said but make sure you use a switch so you can turn it off o and you might want to put a fuse in your line

[Talon007]

Are you sure the car has warmed up enough for the fan to kick in? Check the sensor on the bottom of the rad, on the drivers side.

[kjewer1]

Like talon said, check the sender on the radiator, thats what controls the fan on a 1G. You didnt mention what year car you have. If its a 2g, then the ECU controls the fans. If its a NT I dont know what controls the fan.

[swest_jefe]

its a 90, ill check the radiator sender, hope thats it, ive checked everything else

[boosting20psi]

on the 1g the fan switch is right by our cooling temp sensor i had to replace it like a week ago. the one on the radiator just tells you if your are out of fluid or if you are way to hot.

[swest_jefe]

What do you mean its by the coolant temp sensor, i thought the cts was the one on the top half of the thermostat housing by itself. Are you talking about the single prong one on the front side of the bottom half.

I think I may have found the problem anyway. After running the car for a while, the guage was reading almost redline, but the coolant in the radiator was still cold. I already changed the thermostat once, but i decided to check it again. I run the car with the cap off the thermostat housing and it starts to steam like crazy but nothing ever actually flows through. So then I take the thermostat out all together thinking that might be the problem, still no flow. So Im thinking ive got either a hell of a clog somewhere in the system, or a screwed up pump. (I shouldve known better than to get a JDM) Anyways, if the fan is operated by the sensor in the radiator, that would explain why it wasnt kicking on, because there was no hot coolant circulating into it. But if its operated be the switch on the thermo housing, then I have no idea, because the temp sensor was getting plenty hot.

Either way I need to fix my pump problem, but what do you guys think? Is it because of the switch on the radiator or the other one?

[kjewer1]

The fan switch is on the radiator, as I said above. There is no sensor that tells the ECU if you are low on coolant, besides the one inside the overflow reservoir And there is nothing that means "way too hot." The ECU doesnt care what the temp is, its just to tell it when to activate the "choke" feature, and it also affect timing. There are two coolant temp sensors at the water neck/tstat housing, one for the ECU, one for the guage. I believe the 1Gs have a third, for the AC system. But i'm not sure. On my 2g with 1g motor, that hole is plugged. I only have the one for the guage and ECU, on the tstat housing, nothing on the raciator on a 2g either since the ECU controls the fans.

[swest_jefe]

Cool, that helps out alot. So if i fix the pump then everything should be ok... but im sure ill find something else wrong pretty soon

[kjewer1]

Have you looked to see that the pump is turning? They rarely ever break. Usually a failed pump is one that leaks, but it still works otherwise. Its turned by the alternator belt, behind the double pulley that also does the PS. Of course if it wasnt turning, you'd have no PS either... Strange.

[swest_jefe]

Yeah, the pumps turning fine, its not leaking either. Thats why i was thinking that by some wierd chance something was clogged. I dont know how unless something got stuck in the intake or return line, but you never know with a jdm, maybe something decided to build a nest up in there. Does anybody know a way to test the pump without taking it off? that would make things a little easier

[swest_jefe]

I am confused but very happy at the same time. I was messing with the car contemplating ripping off the water pump and I thought i would try it one last time. I started the car, and after a few minutes it started pumping. After it got hot enough and circulated through the radiator, of course the fan kicks on. I dont know if the pump wasnt able to get a good suction on the coolant or what, but when I first was trying to figure it out I filled the thing and was pouring water in as it was running. I dont know why it just all of a sudden decided to catch like that, I didnt rev it or anything. Oh well, Im going to flush the system just to make sure theres nothing in there. Thanks guys. Time to find something else to fix.

[kjewer1]

Sounds like you had an airpocket in the pump. The water pump sucks at moving air Be sure to let it run for a while to be sure its been "burped" enough.