Sat Nav Won’t Stick To Windscreen – Sorted!


Damn it! Stick already, this shouldn’t be this difficult, right? It’s frustrating, I know, but hang in there and we’ll get this figured out right now.

Sat Nav’s commonly refuse to stick to a windscreen for one of three reasons.

  1. Dirty windscreen
  2. Dirty suction cup
  3. Deformed suction cup

In this short post, I’ll describe each problem in a little more detail and what you can do to fix them. I’ll also include some MacGyver hacks for nailing this repair like a total pro.

1 Dirty Windshield

Dirty windscreen

Sounds too simple to be the solution but in many cases, a dirty windscreen is the root cause of a Sat Nav that just won’t play ball. The Sat Nav cup as you know creates a vacuum when engaged, a smooth grease-free surface is, therefore, mission-critical for the cup to perform.

Windscreens collect grime at a faster rate than you might think. Activities like smoking, dashboard dining, hot drinks all help lay down a layer of grease.

Even some car cleaning products such as dashboard cleaners, dressings, and some air fresheners cause grease to form on surfaces.

Condensation inside the cabin plays a part too. Some condensation is normal. However, excessive interior condensation may be a sign your car has a water or coolant leak or simply that the recirculation button is left on for too long. I wrote a post about heater controls, you can check that out here “How to turn on heater in my car”.

The dashboard and interior plastics themselves through off-gas under sunlight and that too will cause glass surfaces to develop a greasy scum. A suction cup just can’t create a sufficiently strong vacuum through a layer of grease.

Your glass surfaces are under constant bombardment, and the only real solution is to clean them regularly. Cleaning the surface will allow the cup to make perfect grease-free contact with the glass surface.

Cleaning car windscreen

Household glass cleaner will work just fine, however, I prefer automotive cleaners as they’re odorless. Obviously, avoid using polishing materials such as furniture polish, etc. they lay down a layer of wax, great for protecting furniture but for creating a grease-free surface. Check out the windshield cleaner I use and also the anti-fog protection here on the “Car cleaning tools page”.

Lots of MacGyver-type solutions will work too, but only use them in the suction cup area. You could use rubbing alcohol; spectacle cleaner; lemon juice; vinegar; nail varnish remover; white spirits – all will remove the grease but may stink up the interior a short while.

A full windshield degreasing is a way to go, I promise you’ll really notice the difference especially if you do a ton of night driving. Greasy glass causes glare, especially in wet night driving conditions.

The secret to streak-free glass cleaning is to use a top-quality cleaner and two clean dry cloths. I wrote a post about it here “Newspaper to clean windshield”.

2 Dirty Suction Cup

Sat Nav suction cup

The suction cup of course gets dirty too, which makes sense since it’s been stuck to a dirty window surface, or at least until it fell off. As the cup is made from a silicone-based material, it’s best to avoid using harsh chemicals such as those used on the more durable window surface.

Instead, I use household washing-up soap in warm water. Just dip the silicone pad in the warm water to clean, washing the complete assembly is pointless and will take ages to dry fully.

I allow the silicone pad to air dry and the job is complete.

3 Deformed Suction Cup

Heating Sat Nav suction cup

As suction cups live in direct sunlight, UV attacks the mission-critical soft silicone material. It commonly causes them to become hard and deformed. If that sounds like your problem, we’ll need to take some action to help revitalize the silicon.

Although we call them suction cups, the silicone pad should in fact be flat. Problem is, as the silicone pad ages it retains that cup shape, even when not in use.

Reattaching a cupped pad therefore often proves unsuccessful as the cupped pad has a much smaller contact patch. Triggering the suction cup simply breaks what little contact there is, the vacuum is lost and the and you know the rest.

To restore the silicone pad, ie remove much of the cupping, boil some water and pour it into a suitable container, add a little detergent, may as well clean it as we restore it. Submerge the silicone in the hot, but not boiling water.

The heat serves to soften and reshape the cup, you may need to repeat this process until the pad feels alive much of the cupping is removed.

Flame on suction cup

A second option that works quite well, apply a flame to the pad but don’t obviously leave it in one spot or you’ll melt it. Keep the flame moving in a circular motion, just about 10 seconds in total is enough to fix most pads. That’s it, stick to the window, you’re golden!

John Cunningham

John Cunningham is an Automotive Technician and writer on Rustyautos.com. I've been a mechanic for over twenty-five years, and I've worked for GM, Volvo, Volkswagen, Landrover, and Jaguar dealerships. My passion is cars. I use my knowledge and experience to write articles that help fellow gear-heads with all aspects of car ownership, including buying advice, maintenance, and troubleshooting.

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