Modifying roof motor housing with a drain hole?

[benlumley]

Planning to tackle the roof motor replacement over the weekend (assuming parts arrive in time) - bit of googling I came across this:

http://bmwspecialistreading.co.uk/z4-roof-motor-failure/

Amongst other things it says...

Whenever we replace a roof motor on a E85 Z4 we modify the motor housing (box) to include a water drain, preventing this issue returning.

Anyone got any opinions on this? Anyone tried it? It kind of sounds good... kind of doesn't. My thinking is that on the one hand, if water gets in it's obviously better it can drain out. However, if (when) the drain holes into the wheel arches get blocked and water doesn't drain fast enough, you are pretty much guaranteeing the roof motor will get wet, albeit only until it drains. In which case, it'd be better to not have the hole and ensure the box is properly sealed?

What does anyone think?

(I have bought a new box/sound insulation thingy with the new roof motor by the way)

 

[Lillywhite]

I had my roof motor replaced a couple of weeks ago. My Indy also recommended that he drilled a small hole in the bottom of the housing. He said that even if the main drainage was not blocked water might still get into the housing and would not drain out and the motor would sit in a pool of water quickly corroding. The roof motor housing is suspended above the main drainage hole and it is also important to keep this area cleaned out on a regular basis from debris crud etc. and a blast of compressed air should do the job.
I agreed to his suggestion and he also sealed the housing around the joints with some sort of recommended sealant. My Indy told me not to buy a new housing (saving me £56) and he cleaned the existing housing and insulation. I did, however, need a new Bowden cable which had seized and was not disengaging the hydraulics.

My hydraulic pump was badly corroded at the motor end but at the hydraulic end (top) was in good nick and all photos that I've seen on this forum of failed units have the same corroded appearance as in your web-site link. That car had done 40,000 miles, mine had done 39,950 when my motor failed!

 

[benlumley]

Thats one for the yay's then... I'm thinking I'll probably add the hole, should be a good move as long as the drains are kept clear.

I've an open mind on replacing the housing - I can return it for cost of postage; so will see what state it's in + whether or not the new one represents any design improvement. Important bit was to get the parts I'm likely to need to maximise chances of being able to sort it in one go. If there's any doubt, will put it in I think - seeing as all being well, I'm saving the labour etc doing it myself and would rather not take any risks of it going wrong again. Think my Bowden cable is OK - I've got it permanently disengaged and am using the roof manually at the moment. Imagine a seized one complicates the roof removal somewhat, if the motor has completely gone as well!

I've got to 60k btw - imagine it's more age related than mileage though, I notice your car is a 2006 too.

 

[RJS-Z4]

Best of luck, take some pictures along the way

 

[andysat]

Iirc when Bing had his replaced his indy drilled a bigger hole in the bottom of the car

 

[Lillywhite]

I've got to 60k btw - imagine it's more age related than mileage though, I notice your car is a 2006 too.

Yes 7 years old on the 1st September. This problem with the roof motor was notified by BMW within barely a year from the Z4 being introduced and they issued an info sheet about sealing the housing. However, it is now face lift cars that are having hood motor failure and looking at the picture from the website that you posted I'm now pleased that I took my Indy's advice about drilling a small hole.
I shall be on my guard to ensure that the main drainage hole above the rear arch doesn't get blocked up. :wink:

 

[Lillywhite]

Iirc when Bing had his replaced his indy drilled a bigger hole in the bottom of the car

He mentioned that the other day but it won't solve the problem if the housing lets in water and can't escape as shown on the OP's website link.

 

[benlumley]

Iirc when Bing had his replaced his indy drilled a bigger hole in the bottom of the car

I called a few indies for quotes before deciding to get parts and try myself first. One of them said they modify/enlarge the drain holes so they don't block so easily.

Not sure I'm brave enough to go drilling holes in the car myself though!

 

[Bing]

Iirc when Bing had his replaced his indy drilled a bigger hole in the bottom of the car

He mentioned that the other day but it won't solve the problem if the housing lets in water and can't escape as shown on the OP's website link.

I don't understand - having had a good look at the replacement I bought - how water could ever get in the housing from just running down from the top. As I recall, the 'lid' clips over the base, not into it, so water would just run past the join. As long as the entry points for the electronic and hydraulic connections are tight and/or sealed then the only way it could fill up is through the drain holes becoming blocked again. And if they do become blocked a hole in the bottom of the housing will allow it to fill up faster.

My guys drilled the drain holes bigger at the top and removed the rubber bungs at the bottom to reduce the likelihood of them blocking again. Of course they will still need cleaned every once in a while, but I'm happy they've done enough and maintained the integrity of a unit that BMW redesigned but did not see the need to put a drain hole in.

To be honest, if you do the above, and drill a drain hole and clean the drains regularly it's unlikely to fill again ever so an additional hole shouldn't be a problem anyway. I guess we'll have to wait 5 or 6 years to find out if replaced roof motors start failing to be sure :lol:

 

[benlumley]

To be honest, if you do the above, and drill a drain hole and clean the drains regularly it's unlikely to fill again ever so an additional hole shouldn't be a problem anyway. I guess we'll have to wait 5 or 6 years to find out if replaced roof motors start failing to be sure :lol:

True - and to be honest, if I've not had to switch cars for practicality/cost reasons in 6 years time, then a little roof motor aggro isn't going to bother me unduly I don't think...

 

[Lance]

Lillywhite......can I ask what indy you used and if you were happy with their work? And roughly what sort of cost I'll be looking at.

Mines failed too

Cheers

 

[bcworkz]

I recall a few cases where the motor housing was found to be soaking wet and yet the drains were clear. Speculation was water somehow ran along the hydraulic lines and got into the housing. I think more likely is the drains were blocked at one time, then subsequently cleared. Either theory indicates a drain hole would be a good idea. This course of action mean one needs to actively ensure the main drains remain clear, which I'm sure we all do anyway.

The alternative would be to completely seal the housing such that it's completely impervious to moisture. If done well enough, it shouldn't matter if water collects or not. The idea of thoroughly sealing the enclosure of a device that generates heat makes me feel queasy though. Put me in the extra drain hole camp.

 

[Lillywhite]

Lillywhite......can I ask what indy you used and if you were happy with their work? And roughly what sort of cost I'll be looking at.

Senior Garage Services based in Riverside Market Harborough. Contact Barney on 01858 462145. They did a very good job, I obtained the motor from BMW Sopers in Lincoln for £306. Initially they had a problem when the hydraulics wouldn't work but they discovered a problem with my Bowden Cable which was faulty and they obtained a replacement from BMW locally. They charged me £291 labour including VAT for taking off the roof, fitting the motor and Bowden cable and refitting the roof including cleaning out the drainage holes. They also taped round the paintwork where it abuts the roof to prevent any damage.

AutoTech Performance in Telford, who are highly recommended by other forum members, quoted me an all in price of £628 including VAT and parts but a round trip of 190 miles was just too far for me.

 

[Lance]

Thanks Lillywhite, much appreciated.

 

[benlumley]

Did this all yesterday - including the extra drain holes in the bottom of the new housing - the old one was soaked, so opted for the new one as leaving the car with no roof until the old one dries out wasn't really an option.

 

[sharpster74]

Hi all, i'm new here but thought i'd share my experience. Our car is a 2007 3.0 si with just 27k on the clock and the roof packed up last March (motor). I gave the car to a local garage who has quite a reputation for the more fiddly jobs!! They re-conditioned my motor, modified and cleaned the drainage system, and gave me a year's guarantee on the workmanship and i have to say the roof works a treat and has been all summer (hot for once). They charged me 350.00 all in which i thought was quite reasonable.

 

[Derby Z4]

Hi all, i'm new here but thought i'd share my experience. Our car is a 2007 3.0 si with just 27k on the clock and the roof packed up last March (motor). I gave the car to a local garage who has quite a reputation for the more fiddly jobs!! They re-conditioned my motor, modified and cleaned the drainage system, and gave me a year's guarantee on the workmanship and i have to say the roof works a treat and has been all summer (hot for once). They charged me 350.00 all in which i thought was quite reasonable.

That is a good price.

 

[srhutch]

I'm a little confused. Looking at the link the OP posted it looks as if they are drilling a hole in the main housing, not the one that was added to the motor housing on face lift models.

 

[benlumley]

I'm a little confused. Looking at the link the OP posted it looks as if they are drilling a hole in the main housing, not the one that was added to the motor housing on face lift models.

Unsure on the facelift vs pre differences, but the hole is in the black 2 part box it sits in

 

[Liam-O]

I considered drilling a hole but thought that would allow water to get in should it become blocked even at a low level. Once it's wet, the water would soak into the padding and carry on rusting.

I decided to seal the casing with silicon sealant so that even should it become completely submerged, it should be water proof. That and keeping on top of the drainage should mean it will last at least another 10 years