I've developed a leak from the radiator fan switch and it seems to only be leaking around it and not through it, otherwise it works fine. I've bought a new washer to replace the old one and I'm thinking of putting some thread sealant on the threads of the fan switch which should hopefully stop all future leaks. The fan switch looks like a typical fan switch used across the board for many VW cars.

Is it a bad idea to put sealant around the threads? Some say that the threads need solid contact with the metal of the radiator as it acts as a ground and also it might interfere with the sensor temperature readings.

Car: 2004 Seat ibiza 6L

Mileage: 110000 km (63000 miles)

1 Answer 1


Instead of putting an RTV sealant on it, which is what it sounds like you're talking about, put some teflon or liquid teflon type goop on there. The only reason I suggest this is so if needed you can easily clean it off at a later date. Using a sealant is not a bad idea, especially if it is leaking right now. If all you have (or can get) is an RTV type sealant it's no problem, it's just a heck of a lot easier to clean off than RTV.

There is one note to all of this. Double check the threaded boss of the radiator. It might just be it is cracked. Even with sealant it will continue to leak if it is.

  • I'm going to look closer if the radiator is cracked or threads damaged, the sealer I'm talking about is basically like loctite except a sealer.
    – Aden
    Commented Jun 22, 2023 at 18:16

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