How To: Fix inner (lower) engine cover after it cracks

After researching this and reading a short but to the point post on how to fix the inner engine cover, I decided to document my own fix that I performed today.

Materials:
High temperature marine epoxy. I bought LOCTITE brand rated for 300 degrees Fahrenheit.
Lots of clamps. Spring, squeeze, C, or other. Get as many as you can.
Mixing container. I used an empty soda can with the top half cut off.
Strip of aluminum from the local hardware store. It's about 1.25" wide.
File to bevel the edge and remove burrs
Saw to cut it. Bandsaws make short work of this stuff.
Empty frozen pizza box
Some type of matt or sheet of cardboard to protect your work surface.

Step 1, measure and cut the aluminum to length. Don't throw out the scrap. Make it a little long so that you can bevel the corner for a nice tight fit. Sand this or sandblast it. You want a nice rough surface for the epoxy, and later the paint to adhere to.

Step 2, remove the cover and move it to some place with a large flat work space where it's comfortable to work. I used the floor. Before bringing it in, I hit it with the sandblaster where the epoxy will be going. Hold your breath unless your cabinet is big enough for the whole thing. Silicosis is not fun.

Step 3, grind down or chisel away that small rib. You want a flat surface between the hinge mounts. The goals is to have no large pockets to fill with epoxy. It should be a near perfect fit between the aluminum and the fiberglass:
Attachment 22252

Step 4, vacuum up any bits of fiberglass. Again, silicosis is bad, m'kay.
Attachment 22253

Step 5, check your bevel. Test fit the aluminum.
Attachment 22254

Step 6, clean the aluminum surfaces with acetone. Get fingerprints and grease off. It should be pretty clean if you sandblasted it. I also did a very quick wipe of the fiberglass to remove dust and get rid of oils. Don't go nuts here. You don't want the fiberglass absorbing solvent.
Attachment 22255

Step 7, get your mixing container ready. Ever keep around old paintbrushes for modeling, long after they are hard with paint? Now's your chance to use one. Use the handle to mix up the epoxy. Use the whole tube, don't cheap out. Mix for a solid minute to 90 seconds to make sure it's thoroughly mixed.
Attachment 22256

Step 8, use another small brush, or the same one if you wiped the handle, to brush epoxy onto both surfaces. Get a pretty even coating, and get it into all the crevices. Try not to get it on areas you don't want it on. It wipes up easy enough though.
Attachment 22257

Step 9, carefully center up the aluminum strip, beveled side down (you did put the epoxy on the beveled side, right)? and press it in tightly. Start clamping from the middle and work your way toward the ends. My engine cover had little raised areas on the edge toward me that held the strip of aluminum down. Figure out how to lay down your strip before you put the epoxy on everything. Remember that pizza box and the piece of scrap aluminum? Wrap the box around the scrap aluminum and use that to clamp against. Don't use C-clamps directly on the fiberglass!
Attachment 22258

Step 10, clamp. Make sure clamps are tight! Again, start from the middle, work your way toward the ends.
Attachment 22259

Note the pizza box under the fiberglass.
Attachment 22260

Another shot of the pizza box wrapped around the scrap aluminum strip. There are many ways to do this, but this worked for me. I considered using a shop towel but this cardboard just felt right.
Attachment 22261

Give this at least 24 hours before painting. I plan to mask off most of the cover before painting with SEM trim paint. I hear that stuff works well and matches the rest of the trim and engine covers. I don't have this yet but will update this post with additional photos once I completely finish this.

Use your finger to smooth the excess epoxy that squeezes out for a nice clean finish.

Remember, before painting, use a little acetone, sandpaper, or both.

Original post I based this on: http://autos.dir.groups.yahoo.com/ne...s/topics/63402

-Bob, 1982 DMC-12 10904, sitting at 3706 miles as of 9/29/2013

I found that an aluminum bar from HD or Lowes that is riveted to the rear lip of the cover (so perpendicular to the way you did yours) works fine yet doesn't interfere with hinges or with the clearance against the fiberglass.

Whichever way, this is a worthwhile mod to do BEFORE it cracks!

The best epoxy mixing cups I've found are those small plastic 3 oz cups they sell for bathroom dispensers. You will want clear if you mix by volume but they are hard to find. I use the white plastic cups since I mix by weight. They have a flat bottom so your tongue depressor (cut square) does a good job of mixing. You don't want the paper cups because the wax on the paper may contaminate the epoxy.

Quote:

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Originally Posted by Bitsyncmaster

The best epoxy mixing cups I've found are those small plastic 3 oz cups they sell for bathroom dispensers. You will want clear if you mix by volume but they are hard to find. I use the white plastic cups since I mix by weight. They have a flat bottom so your tongue depressor (cut square) does a good job of mixing. You don't want the paper cups because the wax on the paper may contaminate the epoxy.

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I use graduated plastic cups, much like what come with NyQuil. The volume was so great in this case that I ended up using that bottom half of a soda can. It's slow cure so it didn't really warm up. Never mix the 5 minute stuff in that kind of volume unless you want burns or maybe even a fire!

thanks for the great write up. i just got all the supplies you listed at home depot tonight (im just going to paint the piece after its all epoxy'd with some primer and rustoleum black trim spray since i'm out of SEM trim black). hopefully i can get this knocked out relatively soon as my lower engine cover currently bow's quite noticeably when opened.

I ground the center rib out and glued in a polished piece of SS to reflect the engine.

Fantastic work!!

for the not so skilled I sell this SS kit;)

http://pages.ebay.com/link/?nav=item...d=311307944708 http://tapatalk.imageshack.com/v2/15...947bbe7702.jpg

I've been fixing engine covers in this manner for about ten years so you're really on to it here. I use a black powercoated steel bar in the same spot and use either fiberglass resin or urethane to hold it on. Either work well and have never failed but I guess epoxy should work too.
The black steel bar is stronger than aluminum, cheaper, won't rust and nearly impossible to see when installed.
It also seems like a lot less work than your method as it's cut to size, sealed, and ready to go for less money than aluminum stock or as Chris Nicholson would say "Aluminnium"!!!! At 18.99 (#106364G) out the door why bother with a strip of aluminum which has gotten very pricey?
This # is my own assignment so don't look for in the parts manual or DMCH website unless they decide to copy my part design & # some day :)
So many of my original parts designs have been copied by others that it gets a bit frustrating but that's life! The people who do this copying know who they are so I don't need to point fingers! I'm not referring to you either Rob so don't get selfconscious here.
Rob

Quote:

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Originally Posted by rdarlington

Materials:
High temperature marine epoxy. I bought LOCTITE brand rated for 300 degrees Fahrenheit.
Lots of clamps. Spring, squeeze, C, or other. Get as many as you can.
Mixing container. I used an empty soda can with the top half cut off.
Strip of aluminum from the local hardware store. It's about 1.25" wide.
File to bevel the edge and remove burrs
Saw to cut it. Bandsaws make short work of this stuff.
Empty frozen pizza box
Some type of matt or sheet of cardboard to protect your work surface.

Step 1, measure and cut the aluminum to length. Don't throw out the scrap. Make it a little long so that you can bevel the corner for a nice tight fit. Sand this or sandblast it. You want a nice rough surface for the epoxy, and later the paint to adhere to.

Step 2, remove the cover and move it to some place with a large flat work space where it's comfortable to work. I used the floor. Before bringing it in, I hit it with the sandblaster where the epoxy will be going. Hold your breath unless your cabinet is big enough for the whole thing. Silicosis is not fun.

Step 3, grind down or chisel away that small rib. You want a flat surface between the hinge mounts. The goals is to have no large pockets to fill with epoxy. It should be a near perfect fit between the aluminum and the fiberglass:
Attachment 22252

Step 4, vacuum up any bits of fiberglass. Again, silicosis is bad, m'kay.
Attachment 22253

Step 5, check your bevel. Test fit the aluminum.
Attachment 22254

Step 6, clean the aluminum surfaces with acetone. Get fingerprints and grease off. It should be pretty clean if you sandblasted it. I also did a very quick wipe of the fiberglass to remove dust and get rid of oils. Don't go nuts here. You don't want the fiberglass absorbing solvent.
Attachment 22255

Step 7, get your mixing container ready. Ever keep around old paintbrushes for modeling, long after they are hard with paint? Now's your chance to use one. Use the handle to mix up the epoxy. Use the whole tube, don't cheap out. Mix for a solid minute to 90 seconds to make sure it's thoroughly mixed.
Attachment 22256

Step 8, use another small brush, or the same one if you wiped the handle, to brush epoxy onto both surfaces. Get a pretty even coating, and get it into all the crevices. Try not to get it on areas you don't want it on. It wipes up easy enough though.
Attachment 22257

Step 9, carefully center up the aluminum strip, beveled side down (you did put the epoxy on the beveled side, right)? and press it in tightly. Start clamping from the middle and work your way toward the ends. My engine cover had little raised areas on the edge toward me that held the strip of aluminum down. Figure out how to lay down your strip before you put the epoxy on everything. Remember that pizza box and the piece of scrap aluminum? Wrap the box around the scrap aluminum and use that to clamp against. Don't use C-clamps directly on the fiberglass!
Attachment 22258

Step 10, clamp. Make sure clamps are tight! Again, start from the middle, work your way toward the ends.
Attachment 22259

Note the pizza box under the fiberglass.
Attachment 22260

Another shot of the pizza box wrapped around the scrap aluminum strip. There are many ways to do this, but this worked for me. I considered using a shop towel but this cardboard just felt right.
Attachment 22261

Give this at least 24 hours before painting. I plan to mask off most of the cover before painting with SEM trim paint. I hear that stuff works well and matches the rest of the trim and engine covers. I don't have this yet but will update this post with additional photos once I completely finish this.

Use your finger to smooth the excess epoxy that squeezes out for a nice clean finish.

Remember, before painting, use a little acetone, sandpaper, or both.

Original post I based this on: http://autos.dir.groups.yahoo.com/ne...s/topics/63402

-Bob, 1982 DMC-12 10904, sitting at 3706 miles as of 9/29/2013

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This thread went dormant after my post and as I reread what I said it would be easy to misconstrue the meaning. It's a great repair thread that RDarlington has put together and I should have limited my input to letting the group know that I have premade repair plates for this purpose that would save time and money over the aluminum stock that needs to be prepped to fit.

My drifting into other venders "borrowing" my designs over the years should have been left for another day as I had no intention of suggesting that was the case here. I just want to clear the air and let this thread proceed without any further possible controversy. No offense was taken nor intended so please post away as you see fit and keep up the good work!
Rob

Quote:

---

Originally Posted by PJ Grady Inc.

I've been fixing engine covers in this manner for about ten years so you're really on to it here. I use a black powercoated steel bar in the same spot and use either fiberglass resin or urethane to hold it on. Either work well and have never failed but I guess epoxy should work too.
The black steel bar is stronger than aluminum, cheaper, won't rust and nearly impossible to see when installed.
It also seems like a lot less work than your method as it's cut to size, sealed, and ready to go for less money than aluminum stock or as Chris Nicholson would say "Aluminnium"!!!! At 18.99 (#106364G) out the door why bother with a strip of aluminum which has gotten very pricey?
This # is my own assignment so don't look for in the parts manual or DMCH website unless they decide to copy my part design & # some day :)
So many of my original parts designs have been copied by others that it gets a bit frustrating but that's life! The people who do this copying know who they are so I don't need to point fingers! I'm not referring to you either Rob so don't get selfconscious here.
Rob

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well here's hoping my prep work pays off and the clamps are tight enough (any tighter and i feel im risking cracking the fiberglass!) to make a nice strong bond.

Attachment 33463

again, thanks for the great writeup with pics. They helped me out a lot!

When working on experimental airplanes, they say you should not clamp an epoxy bond with to much force. You don't want to squeeze all the epoxy out of the joint.

I still think urethane or fiberglass are better adhesives in this situation as I've used both many times with no failures. I see how the steel roof boxes often separate from the fiberglass body on our cars and it reminds me of how inflexable epoxy is. Although it will probably work I think either of my first two choices is easier and more reliable.
Rob

Quote:

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Originally Posted by Bitsyncmaster

When working on experimental airplanes, they say you should not clamp an epoxy bond with to much force. You don't want to squeeze all the epoxy out of the joint.

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Quote:

---

Originally Posted by Spittybug

I found that an aluminum bar from HD or Lowes that is riveted to the rear lip of the cover (so perpendicular to the way you did yours) works fine yet doesn't interfere with hinges or with the clearance against the fiberglass.

Whichever way, this is a worthwhile mod to do BEFORE it cracks!

---

Here is my own HW/Lowes based solution I came up with 4 years ago. Very inconspicuous, does the job and still looks good!
Attachment 34771Attachment 34772Attachment 34773