Condensation

My Aotosleeper Devon has severe condensation inside the nearside headlight unit. I have found out that the gasket on the rear of the light unit is damaged and possibly allowing moisture in.  I have purchase a new rear cover and gasket.  How do I go about removing the moisture before replacing the new back cover please.

A bag of silica gel?

If headlamp is removed, put it in the oven for an hour or two with the plate warmer setting at 30 degrees? That won't hurt anything as it was warmer than that outside yesterday!!

Can't think of anything else to suggest.

I've observed in our house that there's a device called a hair dryer. I have no need for it, but it might be suitable - on a gentle setting - to warm the headlight in situ, from it's back in the engine bay?

Cymro

I haven't needed one for 20 years Cymro - which is probably why it didn't occur to me. 

A very good idea though, specially if the headlight is not to be removed.

Dave

Having just been through this exercise due to a crack in the rear cover on my Worcester, my suggestion would be as follows.

Wait for a dry sunny day and put the van facing the sun.

Take off the rear cover and push a cotton rag in the space between the reflector and the back of the headlamp unit. Remove cloth, wring out and repeat procedure until little more water is apparent. (It is amazing how much accumulates in this space).

Then remove the bulb assembly (without touching the bulb itself). There is a metal wire clip that simply pivots off.

Using a hairdryer at its lowest setting, blow through the back of the unit and through the bulb entry using short bursts to make sure you don’t overheat the plastic mouldings.

Leave in the sun for a while to fully dry it off before re-assembling.

Don’t forget that run off from the windscreen is an appreciable cause of water getting into the rear of the headlamp units. So if rain threatens then you need to put things back pronto - unless you have a garage of course!

Can I ask you where you obtained your replacement rear cover? I have struggled to find a source (other than complete headlamp units at eye watering prices) and had to resort to gluing up the crack in the original. I suspect being MB your Devon will be similar to my Worcester.

Hope this helps.

Regards Graham

Here is one I think? https://www.ebay.co.uk/itm/Mercedes-Sprinter-Passenger-Side-Headlight-Cover-Genuine-Mercedes-0008266324-/121697204063

and https://www.ebay.co.uk/itm/Genuine-Mercedes-Sprinter-Headlight-Cover-rear-Left-driver-lamp-2500-3500-New/183465428152?epid=8024417933&hash=item2ab76444b8:g:0zsAAOSwSGRbs5kV

Here is one I think? https://www.ebay.co.uk/itm/Mercedes-Sprinter-Passenger-Side-Headlight-Cover-Genuine-Mercedes-0008266324-/121697204063

and https://www.ebay.co.uk/itm/Genuine-Mercedes-Sprinter-Headlight-Cover-rear-Left-driver-lamp-2500-3500-New/183465428152?epid=8024417933&hash=item2ab76444b8:g:0zsAAOSwSGRbs5kV

Thank you Peter - you are magic at finding these items. I have ordered your first reference as I can read the Hella part number moulded into the plastic on the photograph. Although I was fairly confident of my repair, the clip fixing puts a direct strain on the glue line - not to be desired.

Regards Graham

What about switching on the headlamps and using the heat from the bulbs?
Probably a very good reason why that wouldn’t work otherwise I’m sure someone would have suggested it!

Nothing wrong with that suggestion for the final dry out. It is just that there is a large “pocket” between the outer case and the headlamp reflector that can store a surprising amount of water - enough to rinse your hands out in my case!

Graham

For Graham F.  I contacted my local MB commercial depot. Gave my reg No and they sent me one by free delivery the same  day.Cost £32

Thanks constable. I tried to find one through the Hella part number with no success. You have taken the obvious route that I should have thought of in the first place! As commented above I have ordered one through eBay as per Peter’s advice for £29.99 - what a saving.

Thanks anyway - Graham

Thanks for all the advice.  Removed old rear cover and found no moisture behind it but gasket seal was damaged slightly. Played hairdryer through bulb socket and dried the unit out. Placed a bag of cilica crystals at rear of lens and replaced with new cover. This morning lens again misted slightly. I cant see any crack etc in lens or housing, unfortunately, where van is parked it never gets sun on the light in question. What next can I try please ?

Could be the joint between the lens and the reflector?

Are you sure that there is not any residual water between the reflector and the rear of the unit? There is quite a large pocket in this area that can only be checked by wriggling your hand down into it or as mentioned previously by pushing a rag down there to be sure it is dry.

Although you can dry out the reflector part with the hairdryer, etc, if there is a bit of a reservoir below and behind it, then condensation will return.

Sorry if you have already done this but I went round the loop more than once before clearing mine properly.

I assume that you had not been out in the van before noticing the return of the condensation, but had it been raining overnight? If not, then it must be coming from behind the reflector.

Hope you have some success.

Regards Graham

GrahamF   How do I get to the pocket of water ? is it right behind the reflector access via the removeable cover as I have no visability from where I could reach it. Thanks

Constable - Yes the only way to it is, as you say, behind and below the reflector as accessed from the removable cover. It is not possible to see into it, but if you if your hand is small enough then you can wriggle your fingers into this area. Best to just push a cloth down there to show that there is water trapped and then use it to dry it out.

I am away at the moment in Scotland and although the weather has not been that bad overall, it has really rained heavily at times. My glued up cover seems to have survived so far with no return of the condensation. Hopefully upon my return my replacement cover should have arrived and can be fitted.

Regards Graham