Stock Taillight Condensation Information
 

The day my Valenti taillights were delivered I found the passenger side stock taillight with a case of condensation even though it had not rained in months and it was hot dry day. Had washed the car the day before for its weekly wash. When I pulled the stock lights off shorty thereafter to install the Valenti I found that water run off had worked its way passed the gasket and been directed into the taillight housing by a tab the turn signal socket locks against to secure it. I could see that fine grit was collecting on the top of where the gasket seated against the frame of the care and how water also collected there to seep down over time. Pictures below of the gasket and tab. It is obvious to see what is happening. Included a picture of the driver's side showing the same progression but not yet breaching the gasket seal. So if one has OEM taillight condensation, this would be the first thing to check I would think for the source of the water.

This is the design flaw that is easily cured for 99 cents.

Check out all my posts on snowman snot.

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CERBERUS

Certainly is a design flaw. Passenger side is more vulnerable because of the tilt when parking on a street.

A simple fix for the car makers, an integrated lip on the trunk channel over the top black plastic of the light to act as a flow diverter channelling the water over the top instead of under and directly on to the gasket.

I can make it out of aluminum sheet and silicone it on, but tack goo does the job easier.

For the whole 9 yards gasket sealer around the exterior of the gasket joint is a good idea as well (the sealer WILL be breached over time without the water dam).

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CERBERUS

Those are possible solutions addressing the source of water. With regards to condensation itself another one is redesigning the taillight so that turn signal area is not an entry point for water or use LEDs for the turn signal and seal up the back. The Valenti ones I have I can see that even if water drips there that there is nowhere for it to enter the taillight housing. There is actually two issues, water entering the trunk and entering the taillight housing. In some ways its good that the problem is showing up with condensation rather than finding the bottom of the trunk is rusted from water sitting there.

Condensation is NORMAL and normal condensation goes away quickly.
The moisture which collects, remains and increases in volume is as a result of the design flaw.

Design flaw water does NOT collect in the trunk but flows over the top of the tail light, and outside the car. Unfortunately due to the design flaw, water and dirt also flows under the top black plastic housing and assaults the gasket of ANY tail light, whether hermetically sealed or not.

The snowman snot fix channels water over the top of the tail light as per normal but prevents water from getting under the top black plastic housing and into the gasket.

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Water in the trunk is not caused by the tail light design flaw, it is a seperate issue with other causes.

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CERBERUS

it won't fix water in the trunk problem?


Water seems comes through my driver's side Taillights

Try opening the trunk, gently spray water on the back window, watch the water flow, you will see the path over the tunk channel over the top and under the the light to the gasket. Pay particular attention TO WHERE IT GOES AFTER. Your water in the trunk may be coming from somewhere else

It should pour over the lights and exit the vehicle. If it is flowing into the trunk noticeably, something else is amiss.

Possibly the situation of the original tsb of overtightening the light mounting bolts and buckling the metal the light mounts to, thus creating a gap for water to enter, or a misplaced rubber trunk lip seal, or a bad trunk weld, or- or-.

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CERBERUS

Or it could be that the taillight has worked it way loose and needs to be tightened up so the gasket is seated properly. You could pull off the taillight to see if water was coming in between the gasket and the car body by looking at the gasket (only takes 10 minutes). Also there is a rudder grommet where the backup lights wiring runs through the bottom of the trunk to plug into the wiring harness for the rear lights in the trunk that you may want to check out. It is on the driver's side underneath the car behind the bumper. If it is not seated right or damaged water could come in through there where there are wet driving conditions.

And btw RFB, condensation is not normal in California in my experience. Never had any in over 40 years until this car.