coolant spewage

[BP10000]

1995 Golf 1.9 TD, 308k km

I have been having some problems with overheating lately. After starting the car, the temp gauge moves over the course of about 5 minutes, up to the center of the gauge, 90C, and stays there.

But when it's hot out if I accelerate briskly, or am stopped for a long period, the coolant starts to spray out of the overflow bottle. The temp gauge has never moved past the center position. I am running the coolant system with no pressure (the lid only screwed on by one thread) since my bottom coolant hose is weak from diesel leakage. My coolant solution is about 90% water from topping up so often.

If I look in the coolant bottle when it is up to temperature, before it has overheated, there is a white froth on the top, like weak soap suds. No oil in coolant or coolant in oil, but my blow-by seems a lot.

This sounds like a headgasket right? Could it have been caused by having my timing over-advanced for 200km?


The other thing is my rad fan isn't coming on. The 30A fuse in the dash is intact, as well as the fusible link under the coolant bottle in the engine bay. But there is a second slot behind the fusible link, under a clear plastic cover, that had a blown fuse in it, which I have lost. Does anyone know the size/rating of that fuse? I think it was like a  big blade fuse.

[BP10000]

I think my fan problems might be temp switch related. Jumping one of the connections in the switch gives me low speed fan operation, while the other makes a solenoid click in the fan control module but gives no fan operation (probably to do with the missing fuse for one of the speeds)

On the coolant neck on the front of the cylinder head, there are two electrical connections. one on the top with 2 wires, and one on the side with 4. The top one seems to be some kind of high temp fan override switch since when I jump its connections the fan comes on very strongly, if the ignition is on.

Will it do any harm if the fans are running full blast every time the ignition is on for the next week or so?

Can anybody point me to an online wiring diagram for the mk3? the haynes manual sucks!!

[Golf/Jetta]

i'm going throught the same thing with a car i just bought.
front top rad hose gets stiff but not hard as rock, as it can happen with a blown head gasket.
does your rad hose (top front) get stiff/hard as rock?
that soapy solution in the expansion tank could be stop leak.. if there was any

[BP10000]

new developments:
After driving about 40 km at 80kph with the cooling cap loose, I didn't have any problems with coolant overflowing. When I stopped and left the car idling with the coolant cap off, the level in the tank slowly rose until it overflowed the tank. I tested the temperature in the tank with a candy thermometer (don't tell my mom) and it was 75C when I stopped and rose to about 82C as it was overflowing. The dash gauge stayed at just shy of the middle mark.

Today I tested the gauge by grounding the pin on the temp sender connector(as suggested by the haynes manual) which caused the needle to pull slightly further to the left of the off position.

Next test I put the cap back on tight and started the engine. The engine was already warm from driving earlier, and took about 2 minutes to get up to 90 indicated in the car. The top coolant hose seemed to get slightly firmer, but not rock hard.

I then let it idle for another 10 minutes maybe, and there was still no change on the dashboard temp gauge, and the fans didn't come on, and the coolant didn't overflow. I was still able to slightly squeeze the top hose.

To speed things up a bit, I drove around the block somewhat aggressively. There was still no change in the temp gauge, the fans didn't come on, and the tank didn't overflow, but the pressure did manage to blow through the stop-leak holding my lower coolant hose together, ending the experiment (luckily close to home)

Is it possible for old, dirty, weakly mixed antifreeze to lower the boiling point of water?
What's the proper test for the temperature gauge on a mkIII?

[Rabbit on Roids]

if you short your gauge wire out (ground it to something) it should read pegged into the red section.
more resistance = cold temps
less resistance = warm temps
the warmer you get the engine, the less resistance the sender puts out.
so if you touch the gauge sender wire to something grounded, it should bury its self clear over towards the "stop now or you are gonna (profanity removed by moderator) your engine over" section of the gauge.

[veedubcanuck]

 No pressure in the cooling system will make the coolant boil sooner. That is why they pressurize systems... to raise the boiling point.