Cooling System

[pocketrockets 0]

Hi all,

 

I've got a problem with my phase 1 '84 1600 GTi (standard) in that it was overheating when i finally got it on the road and mot'd at the wkend. I realised that the slower speed on the fan wasn't kicking in but the second, hoover-like speed was. After trolling through the forum I found out the cooling fan resistor can be a weak point, as can the thermo-switch. I decided to change out the following last night:

* New nissen rad

* New thermo switch

* New thermostat

 

I then removed the resistor and connected the two wires (58, 58B). Bled the whole system but ran out of time (i didn't finish till 12am!) before the fan could kick in.

 

I come into work today (26 miles of mixed bypass and country roads and sitting in small amounts of traffic so not a small journey) after watching the temperature gauge more then the road and the temperature is holding between half way marker and the next white marker. I here no fan though...

 

Pull into the car park and decide to leave it running and see if fan kicks in. No joy at all and the warning light eventually comes on so i switch the engine off and walk away. Next thing I know my boss walks in the office and tells me my car sounds like its about to take off so i go to check and sure enough (10mins after i leave it) the fan is running full speed. Just about manage to start the engine and the fan turns itself off. The gauge by this time is reading quite low.

 

So to summarise the fan is only working when the engine isn't! Wiring wise the only thing I have changed is to remove the resistor and connect the two wires. All other components and connections remain as standard. This is where the search feature draws a blank for me so any help would be greatly appreciated as no doubt i'll have to try and sort it out over lunch today!

 

Cheers

[jackherer 543]

The fan loom isn't connected to the engine loom in any way so its most likely a loose/bad connection somewhere and just coincidence that its only worked with the engine off.

 

I would check the earth first as it sounds like thats the one part you haven't checked yet.

[pocketrockets 0]

The only problem I have with that is the fan continued to work despite the fact the temperature had dropped quite a way down from the slower speed temperature setting (Going from the gauage the temperature was only about a third up the scale). Technically, it shouldn't have been running should it?

[jackherer 543]

Once the engine is off and the water pump isn't running the coolant in the rad can be a very different temp to the coolant in the engine which is where the sensor for the temp gauge is.

 

If its not a wiring problem, which it probably is IMO, it is possible the coolant system isn't bled fully and there is some air in the rad preventing the fan switch from activating.

[pocketrockets 0]

Ok, thanks for your assistance on this, I'll double check everything over tonight.

[sport1901966 8]

As has already been said check out the earth point (just inside the pass side headlight) - I was having fan problems and cleaning up/repairing this solved them.

 

I drew this diagram, might help you (all the loom is around the thermo switch area so should be easy to check it all out):

 

Edited October 1, 2009 by sport1901966

[pocketrockets 0]

Thanks guys much appreciated. I think the earthing point on the early phase 1 isn't in that location though. The Cooling fan resistor is mounted behind the shock tower mounting point on the passenger side right on top of the inner wing. Pug obviously moved it on later cars. It looks like the earth for it is taken direct to the Ignition amp plate so there isn't really a problem with the earthing side of things there. Definiatley no air pockets either.

 

The problem was actually the so called 'brand new' thermo switch I purchased at the start of the week! I put the original old switch back in last night and the fan sprung into life at full speed on the lower speed setting so for the immediate future its sorted!

 

Thanks again though for the assistance given!

 

Cheers