water ingress tail light

[harrylime]

I have some water leaking into my nearside tail light fitting. It is not a huge amount and nowhere else seems to be affected. Does anyone have a definitive source of the leak and a fix please?

[Cotswold Pete]

Is your a Mk3 or Mk4, the back bulkhead changed between the two.  My Mk3 did have a slight leak at one point, think it was just a case of taking out cluster and reseating.

On Mk4, I would have thought water ingress much less likely.

Do you know if it is for sure coming in the where the cluster is, or whether it is is maybe coming in from top of boot seal and working its way around the boot until it appears near the cluster.

 

[harrylime]

1999 mk 4

[harrylime]

I don't know where it's comong from as I've yet to investigate properly, hence my asking if there's a common cause

[steve2006]

Have you checked the spare wheel well for water ingress too?

[Newbie1]

Shouldn't happen unless the light unit is damaged or water is getting into the rubber boots around the wiring loom at the back.

[Cotswold Pete]

You could check if it is boot seal, by gently pulling at boot seal, if it moves, then means the original mastic has dried and boot seal needs cleaning and re-seating or replacing.

With both my Mk3 and Mk4, the water ingress was near the boot lock, not the clusters, even though the boot seal had actually gone near the rear window.

Did once have a Cavalier where the clusters leaked, and the reason was a mild bump at back had moved the bulkhead by about 2mm, which was enough to ensure the new light cluster never sat correctly, and even with lots of silicone i could never get it to stop leaking. 

[Newbie1]

Silicon really is useless stuff. I've had more luck sealing lights with butyl cord, and it doesn't leave a mess behind.

[GrahamG]

Quote

3 hours ago, Newbie1 said:

Silicon really is useless stuff. I've had more luck sealing lights with butyl cord, and it doesn't leave a mess behind.

 

Butyl certainly seems to be the favoured sealant in the marine environment for through hull/deck fittings and around windows etc.