Still problems with the Rad fan

Boiling over is usually due to lack of sealed pressure while the car is running. Pressure keeps the boiling point higher than normal and when there isn't enough pressure the boiling point is lower. Check your rad cap and have it checked for a possible head gasket. They use a blue fluid within a tube and suck in the air within the rad. If it changes colour your head gasket is blown, or something like that.

The blue fluid in a tube. . . is that the CO2 test? That combustion gases are getting into the coolant lines via a blown head gasket?

But even if this is the case, why is the fan not kicking into its high speed? Perhaps the higher boiling point is preventing the coolant form reaching a higher temperature, thus not triggering the rad fan to spin faster. Does this make sense?

In any case, if it is the head gasket, then its game over. Can't justify the expense.

RIP, my precious Wolfy.

Extra expense? Head gasket $40, VC gasket $10, head bolt kit $30, torque wrench borrow one. Piece o cake. Yes it's the CO2 test and it's pretty good to find out if the HG is cookied. Never heard of a 2 speed fan speed in these cars but sure, say it does exist, your coolant is still boiling and shouldn't , there is something else doing it.

Radiator speed is controlled "only" by coolant temperature. from memory first speed comes on about 205 degrees F and second is about 220. You might have bad rad fan if it's spinning slower than before, or the voltage to it is low. Check it at the fan with a volt meter and also at the thermo switch to see what it is.

I would try jumping the thermo-switch first, as there can be a massive voltage drop in it if it's defective but still-kind-of-switching-on. A "normal" switch would melt down from this, but as it's "watercooled" you might not see smoke.

Ingo

Apologies if this has been suggested before, the beginning of this thread vanished from my news server.

I once had a faulty thermo switch on an 87 GTi where only the highest fan speed would come on. Perhaps you have the opposite problem? The thermo switch is easy to replace. On the '87 it sits on the right side wall of the radiator, close to the bottom. I did this work with my brother, I worked from under the car removing the old switch, and he put a cork in from above. I then got the new switch, he removed the cork and I put the new switch in. Lost so little coolant that a single wipe with a paper towel cleaned it up.

You can easily test if the switch is the problem. Unplug the c>

Great, he gets the fan to spin faster! What has this got to do with boiling coolant? The fan operating a normal speed shouldn't allow for boil over.

OK. I have nothing to loose. I consider myself intelligent and armed with the proper information and instructions, can acquire the confidence to take on the job.

So, this said, where do I find the appropriate resources. Is there a "VW Head Gaskets for Dummies" out there? I already have the Hayes manual that I bought a long time ago at a Canadian Tire.

Whatever the outcome, I have commited myself to buy a new car (probably the

BTW, you're sure its the head gasket. I don't want to pull R&R the thing and not solve my problem.

circulating

Agreed. But, is it now spinning at normal speed? Most of the time now, I can stop the fan with my hand. If its spinning at normal speed, should I be able to do this?

Have you replaced the presssure cap? It increases the pressure in the cooling system that raises the boiling point. If it's bad then it will allow the coolant to boil. Mentioned in aother reply is that the fan comes on low at 205f. Water at sea level, no pressure, boils at 212f so it could be the cap. Just something to check before the head gasket.

Joe R.

I wouldn't just go and change a head gasket ust for fun. Check the rad cap first , then the thermo switch and it that doesn't solve the problem I'd have the co2 test done to make sure that's what it is.

I don't appear to be "bleeding" coolant anywhere. It just boils over out of the reservoir when the engine is idling (not when I am driving; everything fine then). I should also state that if I have the cabin heating vents on full while I am idling, the coolant does not boil over.

"s>

head/headgasket

Agreed. Even on slow speed, I wouldn't try it on mine.

First thing I would do would be to umplug the thermoswitch and jumper the connectors on the harness with a paperclip as another poster suggested, simply because it is the easiest thing to try. Next would come applying 12V directly to the fan itself.

Thermoswiches *do* go bad. It is possible that you have a dirty contact. If it is a 2 speed thermoswitch, it is unlikely that both temperature switches went bad at the same time though. I would more suspect the fan in this case though. Head gasket is unlikely. Don't go replacing a headgasket on whim though. They aren't all that hard to do but it definitely is something where having a little experience doing maintenance can go a long way.

Rich

try your water pump and follow bently instructions on testing efficiency of fan motor Some fans are two speed so one of the fan speeds could not be working.Does your temp indicator inside car coincide with boilover situation.