'93 Golf GL 1.8: Overheating/losing water!

[sylvian]

(Please don't laugh at me I'm a newbie!):

Recently, noticed the water level dropping quickly, and the water temp rising v. quick, on average 100-110+ triggering the warning light, steam coming from bonnet etc.

A friend suggested a failing head gasket, but I checked the oil, dipstick, water, and there's none of the sludgy/gunkyness to indicate this, AND because of what I did next...

I hotwired the fan with a hair clip , drove around 60 miles without a problem. Temp now around 80-90 and less, and it doesn't lose water anymore. I assume this means its just that the fan isn't kicking in when it should meaning the thermostat must be buggered...

So my questions are:

- Should I/how do I replace the thermostat and or/temperature sensor? And where best to buy from?
- Is the big ball supposed to have normal tapwater in, I've noticed an image of a book with '!' on it, and 'G11', which Google tells me is a coolant, but I thought you just put normal water in?
- Anything else to check/replace?

[rubjonny]

1. Run the car from cold and check the bottom rad hose, it should stay stone cold till the gauge gets to half way, then get hot.  If this happens the thermostat is fine
2. Replace the temp sender in the bottom of the rad, you'll loose some coolant but if you do it quick and leave the header tank cap on not a great deal.
3. The coolant system should have a 50/50 mix of water & antifreeze, VW have upgraded to G12+ from G11, 2 bottles from your local dealer should be enough to completly fill your coolant system.

I'd flush the coolant system out and start afresh if I were you, especially if the coolant looks a dirty brown colour.  Basically disconnect as many hoses as you can and blast them all through till the water comes out clear, then refit the pipes and top up with 50/50 water & G12+.  The way I do it is this:
Tip 1x bottle of G12 in, then fill the bottle with water, and tip that in.  Then pour half of the other bottle of G12 into the first bottle, and top both up with water.  Top the system up, then what you have left chuck in the boot in case you need to top up the system

P.S. The 'big ball' is called the header tank, or expantion tank

[sylvian]

Thanks for this! The radiator hose is acting like you said, so I can eliminate the thermostat

Ok i've got the g12+, and will buy a temp sender. The hose bit sounds easy, but first if you can bear my stupidity  :embarassed: some more questions:

* Where is the temp sender, what does it look like?
* With the G12/water mix, am I just filling it up in the header/expansion tank or is this done elsewhere?
* Am I supposed to do anything else when filling, I have read some flushes also involve having the heaters on?

Am really grateful for the advice on this. I've really tried to find these exact answers before coming back!

[Len]

If you want to do a full system flush then yes you would have to do the heater fluid as well.

If your water is brown the I think a good flush out is needed. Brown also means that there hasnt been any anti-freeze in the system just water.

I would have a really good look all around your car, get it nice and hot, check all the hoses, turn the heater on etc.

[rubjonny]

1. The temp sender is screwed into the radiator at the bottom on the passenger side.  It should have a 2 or 3 pin plug on it.
2. Just in the header tank once everything is connected back up
3. Not on a MK3 Golf, as coolant flows through the heater matrix regardless of what the heater controls are set to.  Some cars such as the MK1 Golf cut the flow of coolant to the matrix, so you need to set the heaters to hot in this case.  Basically, if in doubt, set the heaters to hot