Stop water finding its way in through windscreen or rear window seals
“Saved me from having a new windscreen fitted to my Mercedes.”
– Frederick Tomley, Judge.me review
The rubber seal around a rear window or windscreen can develop fine cracks over time, letting water track into the boot or cabin. Captain Tolley’s Creeping Crack Cure uses capillary action to seep into these cracks and seal them from the inside, often for a fraction of the cost of a diagnosis or reseal from a dealer or garage.
Over time this loosens the fitting and opens fine cracks around its base, often invisible until water starts appearing below.
Captain Tolley’s Creeping Crack Cure uses capillary action to seep into these hairline cracks and seal them from the inside, without needing to remove or rebed the fitting.
“Early Rover 75 models have a design fault in the seals for brackets supporting the rear window and its seals – they fail and the car boot fills with rain water. I read about Captain Tolley’s on the owners’ forum for the car, where many users recommended it as the most simple cure. They were right. My car now has a dry boot. Simple, effective and cheap. I recommend this product.”
– Alex, Judge.me review
“Believe in Magic – car boot filling with water every time it rained. £100’s quoted by the garage to fit replacement gaskets and rear door seal. £12.50 bottle of the white stuff from CT and no more leaks, now that’s real magic!! My only complaint: it was by chance I read an article recommending it in a Land Rover magazine. Needs to be advertised nationally and not kept secret!!”
– Phil Looker, Judge.me review
“I was annoyed to find that the leaking windscreen wasn’t covered by my insurance, especially when I found out the replacement cost. I applied the product as directed – it took a few applications and it worked perfectly.”
– James Brough, Judge.me review
Water can travel a long way before it shows up, and a blocked drain or worn door seal can look identical to a seal leak. A quick test saves you sealing the wrong spot:
Rule out blockages first. Check the sunroof drains, roof gutters and windscreen base drains are clear, and that door seals are in good condition.
Soapy water and air: spray soapy water along the outside edge of the glass, then blow compressed air around the trim from inside. Bubbles show where it’s getting through.
Low-pressure hose: with a helper watching inside, run a gentle hose from the bottom corner of the windscreen upward. Avoid high pressure, which can force water where rain never goes.
Mark the spot with tape and let it dry fully before applying anything.
*For best results, apply in dry conditions above 10°C / 50°F and keep the area dry while it cures. Cold or damp weather slows curing, and moisture can dilute the sealant before it sets, so allow extra time if conditions aren’t ideal. If you’re working in a garage or storage space, check if the air feels dry, not just that it’s out of the weather, and allow extra time to cure if it’s damp or unheated.
This works best on a true hairline crack, less than 0.8mm wide. A simple way to check: if you can just about see the crack but can’t fit the edge of a fingernail or a thin card into it, it’s a good match. If you can see daylight through the gap, or fit something into it, a traditional reseal will likely give a better result.
Then the fix is to clear or repair the real source, such as unblocking a drain or replacing a door seal. Sealing the windscreen won’t stop that leak. Once it’s sorted, repeat the tests to confirm the leak has gone. If the tests point to a hairline crack in the seal, that’s what Creeping Crack Cure is for.
Yes, once fully cured. Apply it in a dry spell and give it at least 3 days before exposing it to rain or a car wash, so the sealant has time to set properly.
You can still get a good result on a slightly wider gap by building it up in layers. Apply a bead, let it soften slightly, work it into the gap with a fine tool, then add a fresh coat over the top once dry. This takes a bit more patience than a straightforward hairline repair, but several customers have had success this way on a trickier seal.
Fixed windows such as rear quarter glass can develop cracks in their seals over time, letting water seep in around the frame without an obvious source.
Ageing seals around the boot lid or tailgate are one of the most common causes of water pooling inside the car, often traced back to a single hairline crack.
Sunroof seals and drainage channels are prone to hairline cracks that let water drip into the cabin, especially as the vehicle ages.
Rivets and fastenings loosen with age and vibration, leaving tiny gaps that let water creep in - a common issue on riveted trailers like Airstreams.
