temp gauge/warning light

[martinb]

thought i would post this here too as will probablyy get seen more than in the garage!

The GTI that HIC have enterered into the Ramshackle Rally seems to a bit of a problem with the temprature gauge so was just wondering if anyone could give me an idea of where to start with sorting the problem.

Basically based on what my boss has told me the temperature gauge does not seem to work at all but after you have been driving the car for about 10mins the warning light starts flashing. He assures me that yes he has checked that the car has water in it, the car did recently have a water leak and we replaced the plastic housing on the front of the block which was cracked.

They are supposed to be driving this car to Valencia in under 2 weeks and i already rate their chances as fairly slim (as none of them can navigate and the car has proven tempramental!)and think that they really could do with having a temp gauge   

Any ideas?

Cheers   

[clipperjay]

Well to start the black temperature sender located in front of the block. The resistance sends the signal to the meter on the dash to read the temperature scale can go abit wrong.
A cheap method to sort the flashing warning light is to change out the expansion tank for a MKIII one exactly the same, but newer and loads from tat yards for £3. But to check if its work right get a small wire and bridge the two pins on the plug located on the expansion tank. You can see it leads off to TWO metal pins which makes the complete circuit when the water boils and flashing should appear. To clear the flashing just switch off engine and it will reset itself.

Changing out that plastic housing on the rad could have caused air pockets which can cause hot spots where water does not reach enough pressure to circulate the water to cool things.
try pumping the top pipe and lower rad one with the cap off until it get to about 60C from cold at just before boiling. Then slap the expansion cap back on and run it for twenty mins.
Check the black plug contacts also it might have just oxidised over time sand paper will sort it out.

Jay

[martinb]

Cheers jay, nice one, will give it a try!