Cylinder head cover removal for painting

[Texholdem]

my Cylinder head cover has the paint flaking off and is very unsightly. if I remove it to paint, do I have to replace the head gasket when re-assembling?

Should the mounting surface better be left untouched?

I guess high temperature paint is to be used, but how high and where to get, Sherwin Williams?

[MattBelliveau]

God, I hope not!

I'm pretture sure you are talking about removing the vallve cover, and not the head itself. Removing the valve cover, I would replace the valve cover gasket on principle. Cheap, and might as well while you have it off.

[Texholdem]

Yes, only the cover, the part of the engine closest to the hood insulation .

I think the part is called cylinder head cover, I got a quote from dealer

"According to your VIN#, the correct part# for your cylinder head cover would be 104-010-11-30, which runs for $510.00 plus tax. Unfortunately though, Mercedes does not have that part in stock, either in the US or Germany. It looks as if you may need to check around some wrecking yards to see if they may have any...'

So replacement is not available.

[long-gone]

I think it's generally referred to as the valve cover, though Mercedes might call it a cylinder head cover. I dunno?
Anyway, pull it off and remove the baffle and baffle gasket inside (3 or 4 phillips screws). take it to a machine shop and have them put it in their cleaner. it'll cost about $20, but it will remove most of the old paint and get the oil out of the metal.
When you get it back you'll find that the casting is not that good of a quality, with numerous defects and wrinkles. Use a flat file on the flats and dremel or die grinder with either various barrel sanders or cylindrical stones to get in the rounded areas.
You can get engine paint at an auto parts store or maybe a hardware store. I tried to find a high temp primer but was unsuccessful there so I just used the paint. Read the labels on the cans carefully, it should hold up at 300°+. Mine has been holding up okay but I'm noticing a few small blisters afer only about 6 months. If I had to do it again and had a few extra bucks I'd get it powder coated. Some people have the aluminum polished for a chrome-like effect.

I'd get a new gasket as well, if it hasn't been replaced in a while it will likely be stiff and provide a poor seal if re-used. Even a new one can be kind of touchy and prone to leak if it's not set just right. torque it down to spec, over or uneven tightening can cause a leak in a short time. You'll need to replace that gasket for the baffle too (cheap dealer item), use a good thread lock on the screws (maybe get some Benz stuff from the dealer while you're there).

[rocky raccoon]

You are correct. Do not paint the mating edge. Clean it well and reassemble with a new gasket. Careful on torquing the hold-down bolts. The spec is low, probably on the order of 3 to 4 Nm. Use a torque wrench to get them even. Too tight or uneven will result in an oil leak.

[long-gone]

I think it's generally referred to as the valve cover, though Mercedes might call it a cylinder head cover. I dunno?
Anyway, pull it off and remove the baffle and baffle gasket inside (3 or 4 phillips screws). take it to a machine shop and have them put it in their cleaner. It'll cost about $20, but it will remove most of the old paint and get the oil out of the metal.
When you get it back you'll find that the casting is not that good of a quality, with numerous defects and wrinkles. Use a flat file on the flats and dremel or die grinder with either various barrel sanders or cylindrical stones to get in the rounded areas.
You can get engine paint at an auto parts store or maybe a hardware store. I tried to find a high temp primer but was unsuccessful there so I just used the paint. Read the labels on the cans carefully, it should hold up at 300°+. Mine has been holding up okay but I'm noticing a few small blisters afer only about 6 months. If I had to do it again and had a few extra bucks I'd get it powder coated. Some people have the aluminum polished for a chrome-like effect.

I'd get a new gasket as well, if it hasn't been replaced in a while it will likely be stiff and provide a poor seal if re-used. Even a new one can be kind of touchy and prone to leak if it's not set just right. torque it down to spec, over or uneven tightening can cause a leak in a short time. You'll need to replace that gasket for the baffle too (cheap dealer item), use a good thread lock on the screws (maybe get some Benz stuff from the dealer while you're there). You might also consider putting washers under the cover bolts as the twisting directly on the paint will scrape it off under the bolt heads.

[Texholdem]

Originally Posted by long-gone

When you get it back you'll find that the casting is not that good of a quality, with numerous defects and wrinkles. Use a flat file on the flats and dremel or die grinder with either various barrel sanders or cylindrical stones to get in the rounded areas.

it would be way beyond my skill , maybe I could get it done too; or is it possible to sand and paint without removing? Certainly the backside is hard to reach. Since everything else in the engine bay is old, a shiny valve cover would not look right. i would paint it to a dull, weathered finish.

[73Elsinore]

Having just gone through this I can make some additional comments to the good comments already here that might help.

Originally Posted by long-gone

Anyway, pull it off and remove the baffle and baffle gasket inside (3 or 4 phillips screws).

There are 29 screws or so and for both baffle covers and they are a nasty b*tch to get out because they are self-tapping and they were driven into unthreaded holes when the cover was first assembled. You should use an impact driver to get them out.

Originally Posted by long-gone

take it to a machine shop and have them put it in their cleaner. It'll cost about $20, but it will remove most of the old paint and get the oil out of the metal.

I took mine to the sandblaster. For $40 they blasted it clean using aluminum oxide. You will need to clean most of the varnish out of the inside of the cover first using lacquer thinner or similar sovent. Nasty job.

Originally Posted by long-gone

When you get it back you'll find that the casting is not that good of a quality, with numerous defects and wrinkles. Use a flat file on the flats and dremel or die grinder with either various barrel sanders or cylindrical stones to get in the rounded areas.

+1 on this. The casting is not aluminum; it is either pot metal or magnesium and yes it's pretty rough.

Originally Posted by long-gone

You can get engine paint at an auto parts store or maybe a hardware store. I tried to find a high temp primer but was unsuccessful there so I just used the paint.

I will be using PJ1 flat black motorcycle exhaust paint. Supposedly good to 1500 F (I have my doubts), it requires a curing procedure which makes me think they put some thought into this paint. I am using flat black because I live in a hot climate and I am after every last bit of cooling I can get. Flat black is the best radiative heat emitter there is.

Originally Posted by long-gone

If I had to do it again and had a few extra bucks I'd get it powder coated. Some people have the aluminum polished for a chrome-like effect.

I discussed this with my sandblasting shop who is also a powder coater. He recommended against powder coating, saying they had poor luck on valve covers, that the coating starts to peel after about a year. He recommended painting with a regular two-part catalyzed paint. That is out of my budget right now so I am going with the exhaust paint. Plus, this way, I can patch it myself if nedds be, and the patch will be nearly invisible.

Originally Posted by long-gone

I'd get a new gasket as well, if it hasn't been replaced in a while it will likely be stiff and provide a poor seal if re-used. Even a new one can be kind of touchy and prone to leak if it's not set just right. torque it down to spec, over or uneven tightening can cause a leak in a short time.

+1 on this too. The seals at the spark plug holes dry out and then you get an oil leak down into the spark plug holes. So when you do the perimeter gasket around the cover, do the spark plug hole seals also (cheap).

Originally Posted by long-gone

You'll need to replace that gasket for the baffle too (cheap dealer item), use a good thread lock on the screws (maybe get some Benz stuff from the dealer while you're there). You might also consider putting washers under the cover bolts as the twisting directly on the paint will scrape it off under the bolt heads.

Those gaskets do not show up in the EPC and the parts guy I checked with can't find them either. If you notice, neither the baffles nor the cover plates have MB part numbers on them, which is weird. I will use The Right Stuff when I reseal mine (only because I have some here on hand). Great idea on placing washers under the bolt heads.

[Texholdem]

Maybe it is simpler then it reads but i am getting dizzy right now, to whom changing rotors & pads is already a big archievement.

[73Elsinore]

Originally Posted by Texholdem

Maybe it is simpler then it reads but i am getting dizzy right now, to whom changing rotors & pads is already a big archievement.

Ehhh, it's no sweat. Just get the section out of the manual for this job and follow the instructions. You will need a torque wrench to properly tighten the cover bolts back down. You can get a cheep one at Harbor Fright .

[long-gone]

Sorry about the double post, don't know how it happened.

73Elsinore - thanks for additional notes.
Not sure if we're talking about the same motor. I was assuming Texholdem had an M103 or 104 (mine was an M103). The baffle inside mine only had 3 or 4 screws holding it in. just a flat metal plate with a crimped edge. The gasket is a U-shaped rubber strip that fits in a channel cast in the cover. The crimped edge of the baffle pushes into the "U". The Benz dealer found it in an exploded view and said it was the first one he'd ever sold.

I recommend having it boiled in the cleaner at the machine shop because not only does it do a great job getting most of the paint off but it cleans the inside as well. When you get it back all you have to do is scrape the remaining traces of paint and clean up the numerous burrs, creases wrinkles and flash in the metal.

The only fault I can find with the flat black idea is that matte colors tend to show every mark and scuff with even the most minor contact and oil tends to "darken" it where you try to wipe it off (stains burn off on an exhaust). I used a semi gloss grey metallic that gives a very nice look and contrast to the black air cleaner and predominantly aluminum castings that surround it.

Texholdem - Sound like it's already a dull weathered finish! It's really pretty straight forward, and you don't have to file off the imperfections in the casting if you don't feel up to it, it just makes it even nicer. Torquing the valve cover bolts is a pretty standard practice though LOTS of people just do it by hand, but they tend to over tighten them thinking it helps. The intricate shape, design and gasket thickness on these covers (as well as experience) is why I would recommend torquing them.
I highly recommend NOT trying to sand and repaint it in the car! (especially the sanding part sand and engines don't mix).