HexHead front engine cover corrosion the cause

[Bendy toy]

Last summer, mine was powder coated due to corrosion at the bottom edge. There was cruddy paint all around the bottom screw under the triangular lug. As much inside the cover as outside.
Today I've had the cover off to fix the timing shaft oil seal that I damaged refitting the cover.
I've found the rib where the plastic cover fits over was badly rubbed. Not yet through the coating but certainly not good.
I fitted some washers under the screws but the cover still seemed tight to the metal so I've also trimmed off the little edge flange where it sits over the alloy timing cover. I've left it on at the top where it locates the plastic back cover.
I now have a 1mm gap between the plastic belt cover and the timing cover. Hopefully no more corrosion problems.

Paint damage


Gap to prevent rubbing

 

[cookie]

on two of my bikes, i took the plastic cover off, threw away the sound deadening sponge (if fitted), applied ACF 50 liberally under the cover and where it touches timing cover. copperslipped the cover bolts and refitted. neither bike had any corrosion in that area.

in fact, i also applied ACF50 to timing cover outside the area covered by the plastic, over the torx fixing screws and join to crankcase - never had any corrosion there either.

 

[Bendy toy]

Mine had corroded with the original owner. When I went tidy up the paint (nothing serious) the 2cm2 area outside was 4cm2 inside. There is no road salt inside the cover so has to be a mix of rubbing and dissimilar metals.
I eventually had the engine cover powder coated. The bike has done less than 2000 miles since the paint job and the plastic cover is already fretting against the engine cover rib.
All the belt cover does is protect the alternator belt from stones & fingers so final solution is to stop it rubbing.
My brother's GS has a stainless crud catcher but alloy cover corrosion at the bottom is really bad. All the worse for it being hidden away.

 

[NeilCol]

I'm gonna get my front cover done in the Autumn, and hopefully find a painter who can sort the few areas on the engine block down the side.
Once done and having read about the rubbing of the cover I wondered if some Helicopter tape over the ridge would be a solution? And I also wondered if the spongy bit was there to prevent the cover rattling around causing it to rub. Surely it has some purpose?

 

[Nice 'n' Fat]

I've had a crud catcher fitted since about 3k and now at 54k I still have no corrosion to the front cover or any other area on the bike

 

[Bendy toy]

When I first saw the paint bubble around belt cover bottom edge, the foam pad was intact. I did not have a crud catcher but it would have made zero difference on my bike. The bottom edge of the cover (stone chip area) was untouched yet the bottom two bolt holes and bottom plastic cover bolt areas were a right mess.
Yesterday I could see & feel a clear line along the RHS (left in pic) rib caused by the plastic edge digging into the coating.

 

[Bendy toy]

I've had a crud catcher fitted since about 3k and now at 54k I still have no corrosion to the front cover or any other area on the bike

Lucky you. I stripped my bike & had the frames refinished. It was rusty even in areas that had never been exposed since the bike was built. Those parts could never have got road salted or covered in ACF or polished.
My brother also has an 08 GS his rear frame is much better condition than mine but his timing cover is a disgrace AND that had a Crud Catcher.
So my experience, admittedly with two bikes, is the corrosion is not caused by stone chips.
This had a crud catcher - corrosion around cover screws and shocking under the catcher. Copper grease on crud catcher mounts Dirt is last autumns ACF-50.

 

[Nice 'n' Fat]

Why am I lucky?

It's a June 2006 bike which I have owned and looked after from new. It cost me a lot of money so I look after it

 

[Bendy toy]

You are lucky because you did not by a Mk2 1200 with the rubbish paint finish. The 1150s and Mk1 1200s had a solid finish. Mk2s were crap. Mk3 better but still not up to 1150 standards.

Washing a bike with crap paint make absolutely no difference. Bro's had ACF-50 every week and was put away last autumn with ACF and other oil based protection. It's still come out looking like a WW2 bomber from the North Sea.

 

[Bendy toy]

Pictures from brothers 08 GSA. It's got less than 1/2 miles of mine but front cover is terrible. It's gone just as badly in areas not accessible for cleaning and each time it's corroded under the paint. Engine cases and gearbox are clean.

 

[Bendy toy]

Aprilia Pegaso 650 Mreg
Kept in same garage. It's dirty used all year around and no corrosion in sight

 

[MattW]

The end of that brake pedal is shocking...

 

[Beemerman59]

You are lucky because you did not by a Mk2 1200 with the rubbish paint finish. The 1150s and Mk1 1200s had a solid finish. Mk2s were crap. Mk3 better but still not up to 1150 standards.

Washing a bike with crap paint make absolutely no difference. Bro's had ACF-50 every week and was put away last autumn with ACF and other oil based protection. It's still come out looking like a WW2 bomber from the North Sea.

It can't be inherent in the design of the Mark II's though Bendy as my '08 is fine - no corrosion anywhere other than on a couple of brake caliper bolts I missed from ACF'ing. And it gets ridden all year round, I just never let the salt sit on the bike for any length of time. I fitted a crud catcher when the bike had done about 6K and always ACF before the winter. I think its more the case you have been unlucky with your bike rather than others being lucky with theirs.

 

[Nice 'n' Fat]

I agree

 

[cookie]

from what little i can see, it's corroded cos you've left the bike fucking minging

 

[Delboy777]

from what little i can see, it's corroded cos you've left the bike fucking minging

Thats what you do when you apply ACF50. Dont wash it !!

 

[cookie]

Thats what you do when you apply ACF50. Dont wash it !!

best to check underneath it occasionally. that corrosion did not happen overnight.

 

[Bendy toy]

Last autumn, it was looking questionable under the crud catcher when put away but it was a serious shock when pulled out for the summer.

Thats what you do when you apply ACF50. Dont wash it !!

Yes its dirty but as @Deloboy said, ACF-50 attracts dirt and it is greasy. Also note the state of the top edge that can't be cleaned without taking the belt cover off the bike. The paint flaking is worst where it can't be seen or cleaned and where it can't get salt sprayed.

Black gunk under the alternator belt cover is rubber filings from alternator belt. The bottom edge was hidden behind a crud catcher which might have protected against stone chips (he's got Remus headers with no cross pipe). But the problem is coming from the under bolt heads and has spread from the steel backing around the bottom cover bolt. Its ****all to do with cleaning.

It was looking a little bubbly last autumn but nothing too get stressed about. Pulling it out this spring, most of the bolt faces are crudded up and the finish has just evaporated.

Also note the 1995 Aprilia owned by the same bloke and used all winter. Not exactly clean and yet the only metal oxide in sight is on the brake pedal.

 

[Beemerman59]

Last autumn, it was looking questionable under the crud catcher when put away but it was a serious shock when pulled out for the summer.

I didn't realise you store the bike over winter. What is the environment like that you leave it in? Is it damp, do you cover the bike?

 

[cookie]

the problem is coming from the under bolt heads and has spread from the steel backing around the bottom cover bolt. Its ****all to do with cleaning.

it's salt or similar got under the paint at the raw edges where the cover is machined and where the bolt heads have ground the paint off as they were tightened.

it's all about the cleaning, bearing in mind the shit finishes the BMW use nowadays. hiding the susceptible area up with a big chunk of stainless is an obvious mistake too.