Overheating - Fan not starting

[kurt_wylde]

Wonder if you guys could help..

The radiatior in my girlfriend's 1.4 Ibiza had cracked at the corner, coolant everywhere etc..
So I've fitted a new radiator, replaced all the coolant and tested it for leaks..so far so good.
Taking it for a spin, or leaving it to idle causes it to overheat (Needle heading towards 110 on the temp gauge). I've noticed however, that the fan isn't kicking in.

If I disconnect the plug from the temp switch screwed into the rad, and bridge two of the pins with a wire, the fan starts (Both speeds) so I know the fan/motor/wiring etc is all ok.
I replaced the 3 pin switch in the rad and it's made no difference.

Can anyone help out please, I'm at a bit of a loss now.. for whatever reason, the fans just won't trigger at 95c when it's supposed to!

Thanks

K

 

[andyj]

your thermostat's possibly gone, not allowing the hot water into the radiator, and therefore not triggering the fan......

think a new thermostat is about £5 from GSF

one way of checking is that when your engine's up to temperature, feel the top and bottom radiator pipes, one should be hot and the other cooler (can't remember which way round!)

 

[kurt_wylde]

Ah, sounds possible!

Checking the pipes yesterday and the top pipe is hot, bottom one cold. Both are stiff (ooh err) with pressure once engine is warm.

Is swapping the thermostat out a big job?
(Haven't got the Haynes here in work)

A quick look on another forum shows this:
"Putting in the fluid is done this way...first take off the upper rad hose from the rad, bend it upward and pour the coolant in the hose to fill the block. This fills one side of the thermostat. When hose is full, slip it back onto the rad and fasten. The remainder of the fluid is now added to the expansion tank. It has to be done this way otherwise you will have an air pocket behind the thermostat which will prevent it from ever opening and allowing coolant to circulate."

When I replaced the radiator, I simply replaced the coolant via the expansion tank.
Does that mean I may have an air pocket etc, anc that's stopping the thermostat from opening??

 

[andyj]

if you replaced the coolant via the expansion tank, and then let the engine idle for 15mins, and then topped it up again, you should be ok.....

sounds like your thermostat's working ok, as you top pipe is hot and the bottom one's cold.....

might be a dodgy 'new' sensor. where did you buy it from ? ECP/GSF are not reknowned for the quality of their electrical sensors !!!

 

[kurt_wylde]

Well, I thought about it being a dodgy sensor replacement, but I can't see it.. it was a 3rd party GSF one though.

Would having air trapped in the system prevent the hot coolant from entering the radiator though?
Obviously if it's not getting into the radiator it won't be warming the sensor switch.

As a stop gap is there a problem with running the fan permanantly?
Don't want to burn out the motor etc, but it may be the only way to keep it cool in order to get to a garage..

 

[Dan Cupra R]

Have you checked your fusebox?

I had a similar problem in the mk3 with the fan not working, turned out it was the fuse box

 

[kurt_wylde]

Yea, fuses are fine. As I say, it's not a problem with loom or anything, as bridging the pins on the plug that pushes onto the radiator switch will activate the fan. So it's definately the radiator switch, meaning it's either faulty or it's not getting hot enough to activate.. which I think could be due to some trapped air.

I think I'll flush the system tonight and start all over again!

 

[Dan Cupra R]

I know how you feel, its very frustraiting

 

[jenk]

I replaced my coolant and got an air lock in my heater piping. So heating didnt work. Take the top off the expansion tank and give the pipes a nice squeze seemed to work for me

 

[ScottyDog]

have you tried replacing your rad fan switch

 

[andyj]

have you tried replacing your rad fan switch

yeah he's tried that.. (see post #1 )

 

[Brummy]

had this happen to my 1.4.. top hose hot bottom cooler.. was the thermo .. not too big a job to do

 

[Fl@pper]

bridging the fan will only cool the water in the rad if its not flowing and as you say most likely burn it out

did you move the heater slider to hot before filling ?

does the water actually flow throught the tank ?

sounds like you have an air lock to me but could be any manner of things

 

[kurt_wylde]

bridging the fan will only cool the water in the rad if its not flowing and as you say most likely burn it out

did you move the heater slider to hot before filling ?

does the water actually flow throught the tank ?

sounds like you have an air lock to me but could be any manner of things

Yea, thought as much.

Yup, heater slid to hot, filled and ran the engine for about 15 mins with the blower on full and the expansion cap off, ran it till the coolant was frothing out of the expansion globe!

As the Thermo's only about £6 and looks a 15 min job to replace, I'll do that later on tonight. Then refill the coolant and try (Yet again) to ensure there's no air trapped!

Are 'Stiff' hoses when up to running temp a sign of an air lock?

 

[sweilam]

Wonder if you guys could help..



If I disconnect the plug from the temp switch screwed into the rad, and bridge two of the pins with a wire, the fan starts (Both speeds) so I know the fan/motor/wiring etc is all ok.



Thanks

K

it means there is really 2 speeds ? which one is the normal ? the slow or fast one ?

 

[kurt_wylde]

it means there is really 2 speeds ? which one is the normal ? the slow or fast one ?

Yea, twin speed fan. One is 'slow' speed which is activated at 95c and the faster speed is at 102c.

 

[sweilam]

for some reason mine is always working on the fast speed, and it works on 90C

 

[kurt_wylde]

You might only have a single speed fan (Or more likely, a single speed switch).
The plug in your radiator with have either two or three pins..

But without meaning to be rude, it's taking my thread off topic.

 

[sweilam]

sorry mate, didnt mean to take it of subject.

anyway, i think i will set it to the high speed and leave it, all the ibizas that i saw here are on high speed only. maybe it's like custom specifications for HOT countries.

cheers.

 

[Turbo Boss]

Hello, I am not sure if this is your problemo but under 12V Battery on Skodas and VW there is a small rectangular box that is in charge to drive the radiator fans......... I am pretty sure Seats also have it.

This box have a PC Board with some electronics components and big relays. I saw one of this box on my mechanic office and I open it and it was corroded because water get inside. The water spots on the PC Board looks like white dirt and this was making shorts on the solders. This thing was easyly clean with a WD-40 and a brush........... Then put some silicone so water does not get inside.

Maybe is a good idea that you check this box too.

Also, check this post too: http://www.seatcupra.net/forums/showthread.php?t=89307

Good luck,

Isaac

Here are some pics of that box.