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Grip It & Rip It
Join Date: Apr 2005
Location: SoCal
Posts: 1,219
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Valve Cover Leaking
So i sandblasted and powder coated the outside of my 93 e36 valve cover. I put sealant in the appropriate areas, reinstalled it and it leaks. Here is my plan:
I'm getting a 1/4 torque wrench to re-torque the 15 bolts in a criss cross pattern. Do you think it would be good to resurface the mating surface of the magnesium valve cover? Do they warp over time? Also is there a chance the powder coating warped it? Any advice would be very welcome. I want to do this right the 2nd time. Thx! PS - Sorry to bring this up in the Porsche affiliated forum.... the bmw ones suck.
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82 911SC (sold) Last edited by edgemar; 05-07-2013 at 08:03 AM.. |
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05-07-2013, 07:49 AM
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On my 356, there are different gaskets available, some with a sandwich of gasket material and metal on the inside, some straight gasket material. Some work better than others, depending on QC of that batch of gaskets and what condition the valve cover is in. I've also read about and used RTV or similar to make a better seal.
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05-07-2013, 08:19 AM
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Bandwidth AbUser
Join Date: Nov 2001
Location: SoCal
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Quote:
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Jim R. |
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05-07-2013, 08:27 AM
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Band.
Join Date: Dec 2003
Location: Denver, CO
Posts: 13,315
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Yes, yes, and yes. If there's no lip on the mating surface, throw it on a fine-grit belt sander until the whole mating surface is shiny.
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05-07-2013, 08:29 AM
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Grip It & Rip It
Join Date: Apr 2005
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ok, will do thx!
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82 911SC (sold) |
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05-07-2013, 08:35 AM
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Bandwidth AbUser
Join Date: Nov 2001
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I would recommend using a sheet of sandpaper backed by a real flat surface (glass?). Lay the mating surface of the valve cover on it and sand it until it's even.
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Jim R. |
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05-07-2013, 08:40 AM
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Grip It & Rip It
Join Date: Apr 2005
Location: SoCal
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i'm going to take it to the local machine shop
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82 911SC (sold) |
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05-07-2013, 09:39 AM
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Location: Long Beach CA, the sewer by the sea.
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You don't need to take it to a machine shop. Get some wet or dry paper and contact cement it to some glass or other flat surface like MDF. Move the cover back and forth a bit over the paper and observe the shiny places v. the low spots. If not bad, do that until flat.
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05-07-2013, 10:00 AM
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Grip It & Rip It
Join Date: Apr 2005
Location: SoCal
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thx for the advice. Dropped it off already. They have one of those belt sanding tables.
I'm in an apt. so this is probably my best option.
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82 911SC (sold) |
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05-07-2013, 11:21 AM
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Grip It & Rip It
Join Date: Apr 2005
Location: SoCal
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Got the valve cover back. There is some pitting on the mating surface probably from the sand blasting. The machinist didn't want to go any further sanding it down. Is this thing even worth using?
   
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82 911SC (sold) Last edited by edgemar; 05-07-2013 at 03:48 PM.. |
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05-07-2013, 03:40 PM
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ouch. I would say "no". If you try to keep sanding, you'll open up more voids. And if you try welding, it's toast. You can try JB Weld, but you might as well find a new valve cover. Maybe a huge bead of Curil T.
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05-07-2013, 03:45 PM
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Grip It & Rip It
Join Date: Apr 2005
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makes we wonder why i spent $200 for powerdercoating an old part when a new part is $300
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82 911SC (sold) |
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05-07-2013, 05:38 PM
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Hell Belcho
Join Date: Sep 2006
Location: Oz
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This is what happens when you try to sandblast magnesium. It's history. Time for a new valve cover.
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05-07-2013, 05:52 PM
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Burn the fire.
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Replace. All that pitting is terribad. You'll spend too much time sanding it down and you may take off too much material. Also when throwing them into the oven to bake to powdercoat can cause them to warp as well.
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05-07-2013, 06:24 PM
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Run smooth, run fast
Join Date: Aug 2008
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Before giving up, have a go at it with one of JB Weld's products. They make good stuff.
Lay it on, let it cure the prescribed amount of time, sand it flat, install it, and see what happens. FAQs » JB Weld Maybe contact them for ideas on which of their products they think might work best. This looks like it might do the job: http://www.jbweld.com/product/j-b-pro/
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- John "We had a band powerful enough to turn goat piss into gasoline." Last edited by Heel n Toe; 05-09-2013 at 12:29 AM.. |
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05-09-2013, 12:26 AM
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Grip It & Rip It
Join Date: Apr 2005
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could I fill the crevices with small amounts of RTV between the valve cover and gasket? Would that work?
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82 911SC (sold) |
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05-09-2013, 09:54 AM
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I was thinking about the JB Weld thing to fill the voids, but the expansion and cracking would probably eventually destroy the valve cover, and it's a shoddy repair to boot.
RTV gets hard and will leak. You might have better luck with Curil T sealing paste or a comparable LocTite product like 5910. |
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05-09-2013, 10:09 AM
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Doing some repair with JB is a good idea. Do the thing I recommended when sanding the JB. It doesn't have to be perfect. Clean it well with acetone and a tooth brush because the machine shop got it dirty. It takes 600 º to deteriorate JB. Your VC doesn't see that kind of temp that I know of. |
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05-09-2013, 11:27 AM
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Grip It & Rip It
Join Date: Apr 2005
Location: SoCal
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$15 valve cover in great condition pulled off a wreck. Will sand and paint. Problem solved!
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82 911SC (sold) |
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05-10-2013, 01:24 PM
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2017 Victory Octane
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