Help! Poorly cast M103 valve cover hell! - PeachParts Mercedes-Benz Forum

tinypanzer · #1 03-16-2009, 04:44 PM

Okay, I'm miffed. I bought a M103 valve cover off Ebay to strip and re-paint for the purposes of replacing my leaky, peeling valve cover. The one I got was in about the same condition as mine (or so I thought).

After spending hours upon hours sanding, brushing, scrubbing, etc. I finally got the thing stripped, but I was horrified to see what the metal actually looks like under all that paint and filler (yes, filler!).

This has got to be the most horribly cast piece of aluminum I have ever seen in my life. Pits and voids everywhere. In one spot, a casting pit goes all the way through, and it's right by a bolt post! It turns out that after these things were cast (if you can call it that) they were just buttered over with some sort of grey filler, over pretty much the entire piece. If you start sanding it off, you quickly realize that there pretty much isn't a smooth surface anywhere on this thing. Yes, I am dead certain that this is how it came from the factory, and not a repair. These are straight up casting defects. I should go take a picture tonight and post it, you won't believe your eyes. MB quality my tuchus.

So now I'm sort of screwed. I've sanded this cover all the way down only to realize that I have a hole in the thing. So, I decided to call the stealership and find out what a new valve cover costs. $280. Well, I'm not in a hurry to spend that much for a valve cover. And I've put like 8 hours or more into this thing already.

So, what I want to know is:

Are they all this bad? What is the proper filler to use for this application? Is it worth filling? Anyone got a decent one they want to sell?

Thanks!

-tp

JonL · #2 03-16-2009, 05:17 PM

Pictures!

Cal Learner · #3 03-16-2009, 05:31 PM

Yes, disgusting isn't it? I call it pig iron, but you're right, it's a pukey gray soft filler-like material. I was going to have mine powder coated, but I decided that stuff is so soft, once they blast it with media, it'll be rumpled and pitted and junky looking. I bought a new one from M-B of Anaheim for $223. Still too much, but I needed something better than what was there after 21 years.

Strife · #4 03-16-2009, 11:42 PM

This is surprising, because I've polished 4 sets of 116/117 valve covers and, considering that they weren't meant to be polished, I thought that they were pretty good - considering that this is a pretty complicated, thin item. But a few spots on them _seemed_ to have been welded at the factory where a complete finished piece might have been impossible to do.

Now Bundts, on the other hand...those were forged, and definitely not meant to be polished. They used thick paint, and lots of it, to "fix" them. Really "fixing" them took hours and hours with die grinders, etc.

Mike@Exclusive · #5 03-17-2009, 12:57 AM

you need to smooth the surface out with sand paper or a buffer or something. My boss's wife's 104 in her 300CE had the same problem with the peeling paint and looked like complete ****. I stripped all the paint off of it and hand polished it to a mirror shine. It took a lot of work, but came out real nice in the end.

pawoSD · #6 03-17-2009, 07:28 AM

Do some just hold up better than others? Ours is perfectly nice with the black paint in good condition.

mbdoc · #7 03-17-2009, 08:00 AM

That is why the M103/M102 engines have the epoxy coating.

They are terrible castings. If you use a thick epoxy paint it will look good.

Ron in SC · #8 03-17-2009, 08:13 AM

I just pressure washed mine and blasted nearly all the black paint off. It looks pretty good, it's a 1992 300TE, I'll post photo later.

pawoSD · #9 03-17-2009, 10:07 AM

Quote:

Originally Posted by M.B.DOC

That is why the M103/M102 engines have the epoxy coating.

They are terrible castings. If you use a thick epoxy paint it will look good.

Why did they have such poor quality castings?

Douge · #10 03-17-2009, 12:59 PM

The car I have now 88 300sel is the first one I have had that the paint wasn't peeling badly. I would just lightly prep it and bomb can it with high temp paint. It will look better than 95 out of 100 cars.

tinypanzer · #11 03-17-2009, 06:39 PM

"you need to smooth the surface out with sand paper or a buffer or something. My boss's wife's 104 in her 300CE had the same problem with the peeling paint and looked like complete ****. I stripped all the paint off of it and hand polished it to a mirror shine. It took a lot of work, but came out real nice in the end."

No, this cover is BEYOND that. I have sanded it down and all I have revealed are pits that go all the way trough the metal. I would have to use filler just to stop vacuum leaks!!

Luckily, this guy in California had a couple M103 valve covers sand blasted and ready to paint for the very reasonable price of $50. I just decided to plunk it down and buy one. The photos are pretty nice.

I guess some of these were cast better than others. This one I have here is so poorly cast that I honestly can't believe that they used it at all. I mean c'mon, pits that go all the way through the metal? Give me a break. Stamped steel would have been better.

I'll post a photo of the old one soon.....

pifcat2 · #12 03-18-2009, 09:54 PM

here's another: http://www.mbworld.org/forums/e-class-w124/286723-want-valve-cover-color-suggestions.html

MTI · #13 03-19-2009, 01:31 PM

Having stripped more than a few M102 camshaft covers . . . they are all pretty poor quality surface castings, but why waste the effort if they were going to be coated anyway? The best refinishes I've seen have either been by a lot of elbow grease with a polishing wheel and buffer . . . or powdercoated in brilliant silver.