Rear light clusters again

Z

Z4andy

Member
 Northern Ireland
OK i'm on my third set of rear lenses.

Today the nearside unit is filled with water.

Now before I call the dealer is there something they might not be doing right when they refit the new lenses?

Seems odd and it's annoying as the car has been perfect now for the last year.
 
Its a design fault.
The lights have a clip on cover over the back of the units. The rubber seal is of the wrong material allowing water to enter the unit.
It would have been better if the design was glued together, as i see no reason for the cover to ever be removed.
BMW should be replacing them all with a new design, not just replacing simply because you have a 'duff one'. The only cure is to disassemble the unit yourself and seal it with a load of sealant.
I have done this because i'm out of warranty, and i have had no problems since sealing this way.
 
flybobbie said:
Its a design fault.
The lights have a clip on cover over the back of the units. The rubber seal is of the wrong material allowing water to enter the unit.
It would have been better if the design was glued together, as i see no reason for the cover to ever be removed.
BMW should be replacing them all with a new design, not just replacing simply because you have a 'duff one'. The only cure is to disassemble the unit yourself and seal it with a load of sealant.
I have done this because i'm out of warranty, and i have had no problems since sealing this way.
Click to expand...

I'm not sure I quite understand... because on my car, the clear lens on the outside of the car is what is separating from the main unit, allowing water in from the edge where the indicators are. When I jet wash my car the indicators fill with foam and water from the edge of the lens thats come away...

8830536334_3ea211b1df_b.jpg
 
+ 1 Above. The most common problem is where the clear lens separates from the black casing. Its not obvious until you know what you are looking for but if you push the lower edge inwards, you should be able to see it moving. It looks like the curve of the outer lens doesn't match the casing, almost as if the centre of the casing is being pulled into the body too much.
 
The most common probelm is leaking from inside, only bothered to look at three other cars, all had water to some description. The seperating is just coincidental, and a get out card for BMW.
My business partners 2012 car has water leaking in and no cracks.
Open boot and pour water along the drain gutter at each side and wait.
Might actually need some warming and cooling of the lense to creat a capillery pumping action.
 
I don't doubt there is a problem with the rear seal leaking but there is another significant problem where they split also. This has been validated by the fact that BMW have actually stopped using three studs on the back to prevent the splitting, which I have now seen on several cars. The new clusters Post 2011have only 2 studs and they use a piece of adhesive film to cover the hole when retrofitting onto older vehicles.

Have they not replaced your lights under warranty? My Z is 4 years old and well out of warranty but they were replaced due to the obvious splitting.


The covers allow access to change the bulbs and the connector?


FYI...
Rear_Light_zpsaebd7c67.jpg
 
My vehicle is 2009, the 3 nut version. I have no cracking.
Having silicon sealed the rear housing, i have no leaks.
I wouldn't want BMW touching it!

My business partners car is 2012 6k miles, its left light has a stress crack about 2 inches in from the number plate and is dry, and the right has no cracks, but water can be seen inside under the right conditions.

That BMW doc. is flim flam. They haven't sorted the problem, otherwise some wouldn't be on their fourth set.
 
Confused...

Are you suggesting that my rear lights never cracked? Was I imagining it? Maniac must be too, along with a few other cars I have seen - and the fact that there is a technical Bulletin relating to this:

2010 BMW Z4 Technical Service Bulletin 2010/11/01 NHTSA #: 10041281
Service Bulletin #: SIB-63-14-10
EXTERIOR LIGHTING:TAIL LIGHTS: BMW: THE REAR LAMP IS NOT WATER TIGHT DUE TO CRACKS DUE TO STRESS. WATER MAY ENTER THE LAMP. *RM

What is 'flim flam' about this?

Have you had your vehicle since new?
 
No, i agree my lights may have been changed. I asked BMW what work had been done on the car when i bought it from them. I expect them to be honest with me. The idrive display was replaced as it had died. And the mod to the boot vents had been done. No mention of lights. I have had the car 12 months with no cracking. When i removed the lights there was a fair amount of dirt accumlated, so i imagine they are the original.
That BMW doc. is an attempt by BMW to cure a problem. In this case the cracking lenses, by reducing the clamping load on the lense.
Then they try to blame the cracks for the water ingress.
This obviously hasn't worked as people are still seeing lenses crack.
Having had these units off several times to cure my leaks, i can see what they are up to.The cracks i have seen look like stress cracks within the plastic, problem due to the moulding process. Have seen this with traffic light lenses.The cracks occur when the plastic tries to 'straighten out'.These are quite substancial solid units when off, i would be suprised if the clamping loads are causing these cracks, otherwise mine would be cracked.
The most likely place to crack under clamping stress would be on the corner curves, as the lamps have two locating knobs that sit into the rear wing.
If you have water in the lense, this procedure won't cure the problem.
All that BMW do is change the unit and keep their fingers crossed you don't come back.
I think these units are used on another model, would be interesting if those owners have the same problem.
 

This is the lamp removed.
The two oval cutouts form the rear clip on unit


Take the clip on unit off reveals a rubber sealing strip.
This is made from porous rubber which allows moisture to get into the lense assembly. I coated this in silicon sealant and reassembled and refitted hoping this would cure the problem. it did to a large degree, but there was still some moisture. So on the second go, i left the clip on unit on and used a whole tube of silicon around the join between the clip on unit and rest of the lamp assembly. Sorry i have no picture of that. This cured my moisture problem. So basically the design is bad and the rubber seal they use is made of the wrong stuff to compund matters.


This shows the lamp after a quick wipe over. You can still see the muck accumulation. Water runs off the shiny black trim top right and pours over the clip on unit. Constant soaking the area where th rubber seal suposed to keep water out.

Cracking of the lense is another matter. Could be due to a reaction between the glue and the lense, probably made of Acrylic.I can see how overtightening the nuts on the studs might try to pull the rear moulding away from the clear lense. Perhaps BMW have tried to fit some rubber gromments over the studs and reduce the tightening load on the nuts.
But they are quite substantial units and quite rigid. They would take some seperating. From what i have seen, it would be decribed as graze cracking. Have seen this on traffic light lenses. After moulding and some time after, internal stresses cause cracking. Early traffic light lenese were curved or dome shaped, they usually cracked straight through the centre.
Also had motorcycle indicator lenses do the same.
 
Well a day of heavy rain, and guess what, moisture in my rear right tail light. Strange because when i wash the car down with a hose, i don't get condensation forming.

Well discovered there was still a gap around a mounting stud that was wet, so now resealing that for the third time.
And i have noticed a stress crack.
Think i have said this before, first and last BMW.

Before reassembly have removed the two rubber grommets that the ball stud locators on the outboard edge of lenses fit into, in the hope that any body roll is not transmitted to lenses.
Did mount a camera just in front of windstop to video a few journeys and noticed the the resulting video showed the camera panning slightly left and right as if the rear parcel shift was twisting.
 
I guess there's no chance of a warranty claim now that you have covered them in Silicone? I recently had both replaced under goodwill despite the car being over 4 years old. I am happy to report that I have not had any water ingress since, and there is no sign of cracking as yet...
 
I had mine replaced too about a year ago, there wasn't any issue but it was just done during a service, I've not had any problems with mine.
 
I use a pressure washer when I clean my car and always flush the panel gaps and around the light's.

Have you found this accelerates the water build up or not?
 
I did have one year warranty, but was already trying to get a clunking rear end sorted, and that was costing £100 a vist. As i claimed that was not normal but they going along the lines of normal wear on a 28k car.When i mentioned the water problem, they just fobbed me of with well its does happen. When i said i tried to seal it, they just said, good idea. At that time didn't realise it was such a big issue.
 
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