Pagoda SL Group

W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: Tom in seattle on July 26, 2016, 16:32:22

Title: Fan blade restoration. 250 SL
Post by: Tom in seattle on July 26, 2016, 16:32:22
I have removed the fan blade and clutch.  The blade was heavily corroded and appears that it has been painted once, over existing corrosion.  I have sanded off the corrosion and am tempted to paint the blade but maybe it's "new" state was unpainted, I can't really tell.  Was it originally painted?  Mine is a nice 250sl driver and I'm not trying to zero time it, just drive and enjoy.  What can you advise?
Title: Re: Fan blade restoration. 250 SL
Post by: Tyler S on July 26, 2016, 17:13:37
The original metal finish had some sort of clear coat on it. The blade is magnesium so it turns dark and stains easily. Almost impossible to remove the staining as the surface is porus.  I painted mine with a flat off-silver spray paint. Looks good.
Title: Re: Fan blade restoration. 250 SL
Post by: Tom in seattle on July 26, 2016, 17:28:47
Tyler, thank you.  I'm on the way to the paint store.
Title: Re: Fan blade restoration. 250 SL
Post by: Tyler S on July 26, 2016, 17:40:26
Find something with a bit of another color. Not straight silver as its too bright. I used a Dupli-color "BTY1613".
Has a slight touch of drab olive color in it.
Title: Re: Fan blade restoration. 250 SL
Post by: mdsalemi on July 27, 2016, 14:10:39
Mine had a very rough finish, though clean, indicative of marginally-finished sand casting.
When I changed the radiator and water pump, I sent that out (along with the fan shroud) for powder coating. I can't remember if I had them do a silver or clear, but now it has an extremely smooth finish on it and is very easy to clean.
Title: Re: Fan blade restoration. 250 SL
Post by: Shvegel on July 27, 2016, 17:52:52
I used to rebuild a fair amount of Porsche stuff with magnesium cases and I used phosphoric acid to clean the magnesium to like new. That being said I was stripping some parts a while back and decided to just drop a fan blade in to see how it would work. As luck would have it work called with an emergency and I forgot about the fan for an hour. Luckily I have a spare. 
Title: Re: Fan blade restoration. 250 SL
Post by: Jonny B on July 28, 2016, 02:24:07
Did the tip break off, or dissolve??!
Title: Re: Fan blade restoration. 250 SL
Post by: Shvegel on August 03, 2016, 18:35:42
It dissolved.  Then it rolled in the bucket and started eating the other one.  Darn clean though.
Title: Re: Fan blade restoration. 250 SL
Post by: wwheeler on August 03, 2016, 19:51:19
Like Michael, I powder coated mine. It is wonderful and more importantly for me, it will stay that way. I have never had any luck powder coating aluminum with clear and cast parts are even worse. I know this is mag, but should be similar. The base metal continuous to "bloom" underneath the clear coating. Not sure why and yes it was done professionally. So after a couple of years, it becomes mottled. With steel, I have no problem with clear.

I used a Bengal silver powder (no clear on top) from Tiger Drylac. Most pro shops will have it. It looks pretty darn close to cast aluminum. Not bright aluminum like many colors. It has a dark fleck in it that gives a cast look. It is not a high gloss, but glossier than bare aluminum. The gloss does fade a bit over time.

In fact I have powder coated many of these parts, water pump and thermostat housing, etc. It gives a very uniform look to the engine compartment. You have to know what to mask off when doing the later parts or you will get into trouble.