Finding an obscure leak is not easy but this methodical approach works fine. Remove all carpets and other stuff and with rear seat squab laid flat put a small person in the boot armed with a torch.
With gently running hose starting low down, work upwards to each point mentioned below. Play the hose on each area for several minutes while the assistant uses the torch to see if water gets in. Don't go higher until all the lowest points are tested. Slowly work upwards until the assistant yells "WATER" and stop right there. Mop up the puddle and test again from below that point until the water just appears again. The choice now is either fix or continue because seeing the next higher leak is tough if water is already getting in lower down. Either way, continue in the same vein until all the mentioned places are covered. Do not use the hose under pressure.
From the bottom up, these are places where water gets in the boot.
Corroded boot floor - common when water problems have been allowed to persist
Rusted wheel arches - common in well-used cars
Towbar fixings - common where towbar is subsequently removed
Rear bumper fixing bolts - common
Badge bar - rare but common if removed and refitted
Rear panel seam below and towards the outside of the rear lights above badge bar - common
Rear light gaskets - very common
Spoiler fixing holes on Vitesse - rare unless spoiler removed/refitted, water exits on boot trim
Rear wiper seal - common but only small amounts into upper boot area
Rear quarter light window seals - rare
Rear hatch seal - rare, but more common if damaged or hatch door is not tight
Rear window to hatch seal - common particularly if rear window is removed and refitted
Broken rear sun roof tubes - rare
Same tubes disconnected from exit hole - common if bodywork repairs carried out
Badly fitting/broken rear washer nozzle clip - ? slight effect in boot, causes tailgate corrosion
Click here to reveal solutions to all the above issues.
Rover SD1 Tips 'n Tricks - #3 - Curing Water Leaks into the Boot
A frequent question from SD1 owners is about detecting and curing water leaks into the boot. Of all the cars I owned only the SD1 consistently leaked water into the boot area via so many different entry points. Problems started quite early in the SD1's life because Rover issued a technical bulletin to dealers defining corrections when customer's complained. That bulletin was later revised. Quality engineering - not!
Now, 20 or 30 years later, the problems are worse because of the age of the cars and their early propensity to leak like a seive. Experienced SD1 owners mostly know what to do about the problem but no matter how clever we become, the problems do seem very persistant. What follows is my cocktail and distillation of the Rover Technical Bulletin, wisdom learned for other owners and first hand experience.