Valve Cover Refurbishment - Schrödinger's Cat

[Tomnistuff]

Today I discovered that Schrödinger's Cat is dead.  I was trying to verify that my valve cover is really degreased before putting it back on the engine.  I stuck my finger inside the open end of the long crankcase ventilation baffle that is riveted to the inside of the cover.  My finger came out black, greasy and gritty. The gritty part bothered me - a lot.  I spent about another two hours trying to clean it to no avail.

Like the state of Schrödinger's Cat with the box still closed, I could not know if it was clean without disassembling the riveted baffle.  Using the search tool, I could not find any trace of a cover being disassembled on this site, so I opened Schrödinger's Box, so to speak.  I drilled out the "outer" row of four steel rivets that don't go through the cover and, with a sharpened screwdriver, cut the heads off the seven aluminum through-rivets of the "inner" row.  The cat was dead.  There was so much baked on grunge and heavy grease gritty crap (probably carbon particles from fifty years of blow by gasses before the rebuild by Metric Motors), that I can imagine all kinds of engine problems resulting.

I have cleaned the baffle but still have to clean the inside of the cover under where the baffle was.  Then I will reinstall the baffle by drilling and installing small self-tapping screws where the rivets were.

In the end, I hope to have resurrected Schrödinger's Cat.

I will post an update when I am done, along with a couple of photos of what the under side of the baffle is supposed to look like. 

Tom Kizer

[Benz Dr.]

Boy, some guys never sleep. 

   I used to blast a lot of those parts until I realized that any hidden oil or crud would catch all of the grit and anything like that has to be perfectly dry before you start, which isn't possible. I have all of that sort of stuff cleaned in a cyclone wash now.

[mbzse]

.../... the long crankcase ventilation baffle that is riveted to the inside of the cover.../...  There was so much baked on grunge and heavy grease gritty crap.../...

Tom, this is interesting! I have (until now) tried to clean out this area via the openings. Never felt quite confident that I got all the stuff out. But, I never took the step to actually drill the rivets out.
Now, inspired by you, I will work on one of my spare cam covers, and look inside.
Yes, please post your update with pictures. I attach one here as well

[wwheeler]

Tom,

Have you though about what you will use to secure the screws against vibration? Maybe Loctite or such? Last thing you would want is for those to come out. Can't wait for the pictures!

[stickandrudderman]

Guys, just put the r/c in an ultra-sonic bath and do something better with your time!

[Tomnistuff]

I don"t have a three-foot-long ultrasonic bath.
The photos I've attached are after a long time submerged in a hot bath of simple green and a few minutes of hot water flushing through the ventilation hole followed by brake kleen flushing through the ventilation hole and more hot water flushing.  The only thing I accomplished was to stink up the garage.  It's below freezing here and the garage doors were closed.

The last photo shows the consistency of the stuff the next morning after I took off the baffle last night.  You can see that it came off in dry, brittle flakes, even though it looked to be the consistency of black butter.  It certainly is capable of plugging holes.

I don't know what that plastic (I think) thing is at the end near the fill hole, or the black blob next to it.  It may be the blob that ate Cleveland, for all I know.  I haven't attacked it yet.

Regarding keeping the screws from falling out, I'll burn that bridge when I get to it.  Probably drill, tap and tiny screws with red loctite and lock washers.  I'm certainly not sorry I drilled out the steel rivets and shaved the heads off the aluminum ones.  It was a choice between crud in the cover or sand in my ears.

Tom Kizer

[Tomnistuff]

Hans, (MBZSE),

 I blew up your photo at the end of the baffle and compared it to a blowup of mine in the same area.  I think I see the tail of Schrodinger's Cat sticking out.  I suspect that the valve cover in your photo is in similar condition to mine.  I suppose Mercedes-Benz never expected these cars to get as old as ours are.

Tom Kizer

[mbzse]

Tom, thanks for comments and pictures!  Hmm, seeing this didn't do much good for my trust in a clean environment inside my engines...
Colin, does the ultrasonic really release and flush this residue out of the baffle?

[Jack Jones]

Guys, just put the r/c in an ultra-sonic bath and do something better with your time!

Colin, As I am reading all the issues with drilling out the rivots etc, I'm saying to myself "Am I ever glad I have an ultrasonic cleaner". Then I read your response. I must say this is one of the best investments I have made.

[Tomnistuff]

I cleaned up the inside of the cover for about 45 minutes, which did not clean it up as much as I thought it would.  Even a brass and a steel tooth brush didn't help much.  This stuff is so tough that I think an ultrasonic cleaner would just make it angry.  At least what's still there is so "there" that won't fall off and get into the oil passages.  The plastic (I think) thing that I called the blob that ate Cleveland in the sixth post, turned out to be a part of the thing next to it.  I still think it's plastic but it's really hard like Bakelite and partially melted or at least deformed by heat or age.  I would have to destroy it to know what it really is made of and there's no part number in the EPC, so I'm going to put it back as it is and hope it doesn't wake up while I'm doing so.

Since I'm getting ready to put things back together, I thought I would photograph the "thing" near the ventilation hose end of the baffle and where it goes just to document my work for the group in case I don't survive this task.  I really should be wearing gloves to handle some of this stuff.

When the inside is correct, I'm going to follow Cees' example back in 2004 and paint it (after appropriate preparation).  If it's not ready for paint yet, it's not far.  I tried everything that Kent Bergsma recommended and managed to get everything on the outside really, really clean but there are too many "textures" and "tones" on the aluminum to make it look natural without paint.

Cees, is your mag wheel painted valve cover still acceptable after 13 years?  It still looks good in the photo, but I guess that's not the same thing - huh?

Tom Kizer

[stickandrudderman]

To be fair, I have never actually put a R/C in the ultra sonic bath. Perhaps I'll try it on one of my spares and then de-rivet the breather assembly.
Everything else I've put in the ultra-sonic has been cleaned brilliantly but I'm old enough to know that one can never know everything and every day is a school day.

[Tomnistuff]

Also to be fair, I don't know anything about ultra-sonic cleaners.  I was just trying to give some personality to the junk under the baffle and to express the difficulty I had in removing it.  Maybe the Schrodinger's Cat analogy was better than I expected it to be.  Even when mine is clean, and reassembled, it won't be any help to others unless they drill out the rivets too.  Your experiment of ultra-sonic cleaning, then removing the rivets to know if it worked may be the only way to really know that it works.  The true objective, I guess, should be to be able to know it's clean without disassembling it.

I can't believe this issue has never arisen in the history of Mercedes cars.  Maybe I should have kept my mouth shut and just put the damned thing back on the engine dirty.  Someone said, "Ignorance is bliss."

Tom Kizer

[wwheeler]

How about using one of those snake cameras? Kind of a miniature version of what the plumbers use for drain pipes.

[Tomnistuff]

That's an excellent idea.  At least one will know whether it's necessary to drill out the rivets after.  If not, a lot of work is saved.

Tom Kizer

[Shvegel]

Tom,
These are my parts after a very fine bead glass beading and a very thin coat of Nyalic polymer coating.  The glass beading is done at a very shallow angle to sort of polish the surface and the Nylic helps to tone it back down to the look of fresh cast.  I cleaned my cover beforehand by plugging the breather hole and filling up the cover with lacquer thinner.  I cleaned it after with soap and water.

[Tomnistuff]

That's a very nice effect.  It looks factory fresh.  Some of my engine's aluminum parts look original like that, after Metric worked on them, but my cover even shows different colors and textures in the metal flow patterns from the die casting process.  If it had been sand cast, it would probably have held up better.  I suppose glass blasting might help, but I don't want to do something irreversible.

I think mine is probably, at this point, a better candidate for a paint job.

Tom Kizer

[Tomnistuff]

I finally got my valve cover back together.  I drilled out the center of the outboard rivets, expecting the rivet remains to come out with the drill bit, but no luck.  Instead, I ended up with a 1/8 inch hole through the approximate center of each of the four steel outboard rivets.  So I tapped them to M4 x 0.7.  The rivet remains still didn't come out, even after drilling and tapping through the steel rivet length, but not through the aluminum at the bottom of the rivet hole (except for one that I didn't catch quickly enough)..  They are probably molecularly welded in place (steel to aluminum press fit after 50 years).  I used M4 x 0.7 x 12 long Phillips Pan head screws in the outboard holes.

The inboard aluminum rivets, after the inside heads had been cut off with a sharpened screwdriver, were easy to drive out from the inside with a skinny nail set punch, leaving (7) 12 mm long by 4 mm diameter through holes.  I shortened the rivets to about 5 mm and set them aside.  Then I tapped the holes, from the inside of the cover, using a #10 x 24 English tap (because that's the size of screws that would work in a tapped 4 mm hole.  I shortened the screws to 7 mm - 5 mm for the inside end of the holes, 1 mm for the baffle thickness and 1 mm for a #10 lock washer.  That totals 5 mm of rivet and 5 mm of screw to go in each 12 mm thru-hole.

I used a little medium grip (blue) thread locker (that's all I had) and put it all together with the screws and lock washers.  I even put a little thread locker on the shortened rivets before driving them back into the holes on the outside.

It looks like it's going to work since I didn't tap the holes quite deep enough from the inside for the screws to seat without some pretty heavy torque due to thread interference. 

If I were to do it all again and had plenty of time, I would drill out the outboard steel rivets completely and drill through the outside of the cover (the drill will come out in the center of the bottom of the four indentations on the driver's side of the valve cover.  Then I would do the same kind of thru-riveting as was done on the rivets on the top center of the valve cover).  Long 4 mm aluminum rivets (or something close) are available from Spruce Aircraft Company.  It would require an arbor press with some rivet setting tools to do the job right.  With all aluminum rivets, one could periodically remove the rivet heads, drive out the rivets, clean the ventilation chamber and rivet it all back together again in probably an hour.

Oh Well, live and learn.  Here's what mine finally looked like when I finished.

Tom Kizer