Hi,
My civic is a DX coupe 93 and it's overheating sometime and lost some coolant.

I tested the fan this week-end and it start when I plug it on the battery but it didn't work when I open the hood with the ignition off when I overheat...do the fan is not suppose to work until the car is cold down same if it don't run?

For the coolant leak I think it's the collar between the reservor and the radiator, I often have coolant there on the radiator top...and I don't see any other leak. I repair that but I need to test now if I loss still some more...

My car overheat when I'm a long time in traffic, or that I use too much the heater like if it's not able to cold the coolant after its used than is warm faster and when the radiator is low. What can it be? The thermoswitch of the fan? Do I have to remove all the coolant to change that? The water pump? Or what else?

Thanks
Mel

 

It would help if you would clarify some points, as there can be many causes for overheating.

Do you believe the engine overheating is due solely to coolant loss?

Or do you believe that the overheating is due to a failure of the radiator fan to turn ON when the engine is hot? If you believe the fan does not turn ON at appropriate times, then check whether fuse #13 in the under-dash fuse/relay box or fuse #33 in the under-hood fuse/relay box is blown. If these fuses are fine, then you might have a faulty radiator cooling fan relay or coolant temperature switch (see picture).

You should also check whether your thermostat may be stuck closed.

[IMG]local://upfiles/25538/A5F6E1D31D3B4552B06239ED81EF25E6.jpg[/IMG]

 

Yup, I'd Say Make Sure And Check The Fuse And The Thermostat. My Civic Was Losing Coolant And Overheating Because I Had A Bad Thermastat.

 

I think it's the fan that don't turn on...and I loose coolant between the reservor and the radiator when the coolant become warm...I know that I have to fix the tube between the two and it will stop loosing coolant from there.
I tested the fan by unplugged it at the radiator and plug it direct on the battery. It turn on. I checked the fuse in the box under-hood and it's good. I will try to change the thermoswitch of the fan this week-end...can I do that without removing all the coolant?
Thanks
Melanie

 

Did you also check whether fuse #13 in the under-dash fuse/relay box is blown?

If this fuse is fine, then my recommendation would be that you check:

1) The Cooling Fan Relay (see pictures).

2) The Coolant Temperature Switch (see picture in following post).

3) The Thermostat (see picture in following post).

[IMG]local://upfiles/25538/A19DEFA5608D4BC89DFF521EE7A0300E.jpg[/IMG]

[IMG]local://upfiles/25538/466ED9CFE03146DBA92D0B7F00084E87.jpg[/IMG]

 

Next picture...

[IMG]local://upfiles/25538/43E41E6F0B404238A9CE02F2356A6CEC.jpg[/IMG]

 

Last picture...

[IMG]local://upfiles/25538/BAC29A24C17E439088C0C7DFCDFB79CF.jpg[/IMG]

 

first of all , make sure that there is planty of coolant, if low , do a pressure test. test the cap as well. if any leaks, repair as needed

If coolant is ok.. let the car warm up,, once warm, feel the lower rad hose, it should be almost as hot as the top hose ..if it is t-stat is opening up ok...

If lower hose is cool or just warm, t-stat is sticking close , replace it

If t-stat is ok,, let car run some more,, if fan does not come on........on the t-stat housing there is a fan switch, ( thermoswitch as shown in the picture) while car is running , engine warm of course,,unplug the connector and jump the wires together , if fan comes on,, you got a bad switch..,
,if fan still does not come on,, than chk to see if there is power at switch.......if there is power you got bad wiring from switch to fan motor or a bad motor .

If no power , could be a fuse or relay or wiring from fuse box to switch

keep us posted

 

Ok, when the car is warm the lower hose and top hose are warm.
When the fan come on do the gauge in the car is just below the half or it suppose to be higher?
The fan come on when I jump the thermoswitch...than it left to know if the fan start when the car is warm but right now I never see it start.
Thanks for your help!

 

I think the reading on your temperature gauge is fine. It sounds like replacing the thermoswitch will solve your overheating problem. Be sure to fix the coolant leak as well.