water leak finding spray

[AW10]

I'm trying to find the source of a water leak into the boot of my 5 series estate. It doesn't seem to be the usual culprit of the panoramic sunroof. The hatch and glass seals both look fine, seem to be properly installed and are nice and pliable. I stumbled across a water and wind leak finding spray http://www.shopwurthusa.com/wurthstorefront/Chemic... in the US but there doesn't seem to be a UK equivalent. Any ideas on what else I can use? I have put some of those adhesive dots that are used on mobile phones to note water damage in some places but they're tiny and tedious!

[andyiley]

I take it the link you pasted is a joke.

[marshalla]

Food colouring, watering can, water. Mix 2 in the other and apply.

[AW10]

andyiley said:

I take it the link you pasted is a joke.

No, why? It seems like the spray makes some sort of powder lightly stick to the surface and the wind/water than shifts it allowing you to see where the flow is.

[AW10]

marshalla said:

Food colouring, watering can, water. Mix 2 in the other and apply.

The frustrating thing is that I can not find the point of entry, just where it collects. I have spent loads of time with a hosepipe and can not get water into the boot area yet after a good rain there it is. Hence the idea of the spray to try to narrow down the search. It collects in an area obscured by the tail gate so I can't even crawl into the boot during a rainstorm and watch the water appear.

[David A]

AW10 said:

The frustrating thing is that I can not find the point of entry, just where it collects. I have spent loads of time with a hosepipe and can not get water into the boot area yet after a good rain there it is. Hence the idea of the spray to try to narrow down the search. It collects in an area obscured by the tail gate so I can't even crawl into the boot during a rainstorm and watch the water appear.

Sounds like the water is pooling somewhere and then overflowing. Have you been spraying with hose continuously for 30mins?

OR does it appear after driving - coming up from puddles underneath or running backwards along the body?

[AW10]

David A said:

Sounds like the water is pooling somewhere and then overflowing. Have you been spraying with hose continuously for 30mins?

OR does it appear after driving - coming up from puddles underneath or running backwards along the body?

Pooling is a possibility; I may not have run the hosepipe long enough. It happens when the car sits still overnight. I think I may have narrowed it down to water entering the tailgate somewhere and then exiting the tailgate but inside the seal. But too soon to tell what the exact path is - more disassembly required.

[Martin350]

Tail light gaskets are quite a common leak point on some BMWs, and (probably) cheap to buy and easy to replace.

[Athlon]

Strip the boot area out so you can get to the metalwork the lightly dust with talc.

Leave until it rains and there will be trace lines in the talc where the water has run, follow to the source.

[AW10]

Martin350 said:

Tail light gaskets are quite a common leak point on some BMWs, and (probably) cheap to buy and easy to replace.

A tenner each but unfortunately no difference.