Repairing frame rust and epoxy coating

[DrWin]

So, now I got the fuel tank out and I think I may have to do something about this:

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But what do I do? I guess I have to grind the frame down to where it isn't rusted and then... (?)
Do we have a product to cover the frame up with that does the same and looks the same as the original epoxy?

[Mark D]

There are quite a few different ways you could go with repairs. POR-15 rust preventative paint is a common fix, or you could strip the panel completely to bare metal and have it powder coated. For the repairs to the frame itself you probably don't want to completely remove it and strip it down for powder coat, so spot repairs are usually the way to go.

My fuel tank closing plate wasn't quite as rusty as yours, so I used POR. The process involves quite a bit of prep, but basically it goes like this:

Remove all flaking epoxy with sanding discs / wire wheel. Feather the edges to avoid hard lines between the existing epoxy and the repair.
Remove rust from bare metal using sanding discs and wire wheel.
Apply POR Metal Ready Etching solution
Apply POR Rust Preventative Paint
Apply POR Primer (This will allow a top coat to stick to the POR rust preventative paint. It will also build up the paint thickness to match the OEM coating)
Apply Top Coat (Rustoleum Smoke Gray is a good color match)
















This thread may also be helpful, and there are more pics of repairs on the frame itself.
http://dmctalk.org/showthread.php?51...lor-Comparison

There are other products besides POR that are more user friendly and require less prep, and are easier to top coat. Rich_NYS is in the middle of similar frame repairs and you can see his thread here:
http://dmctalk.org/showthread.php?17...rage-find-quot

He's using a product called Mastercoat instead of POR-15

[Mark D]

Also, the source of all that damage is a leaking brake master cylinder. Brake fluid softens up the epoxy causing it to flake off, then water gets in causing rust. Looks like you'll need to replace the master cylinder, and your brake servo (booster) is also looking like it suffered some damage from the leaking brake fluid. Unless it has holes rusted through it causing it to leak, you can probably just clean it up and repaint it black.

[JohnnyK]

If you're getting that far into it anyways, I would at least use a good catalyzed product instead of a POR style product (or any single component product). I uesd epoxy primer then a urethane topcoat.

[David T]

If you're getting that far into it anyways, I would at least use a good catalyzed product instead of a POR style product (or any single component product). I used epoxy primer then a urethane topcoat.

The benefit of using POR 15 (or another product like it) is that you don't have to remove every last bit of rust. POR 15 encapsulates the rust so it can't spread. Most other paints don't do that and will eventually fail if there is any rust left. Unless you chemically treat the surface of the steel with acid to dissolve every last bit of rust, or sandblast, you can't get rid of the rust. As for the bad master cylinder, it may have been replaced long ago and hasn't leaked in a while but the damage to the frame coating was done. Check and see if it is leaking and if it isn't then you don't have to replace it (at least not now). Also check the hose from the clutch fluid reservoir to the clutch master cylinder. If it looks like it is "sweating" it should be replaced. Brake and clutch fluid needs to be flushed at least every other year or you wind up having to replace the cylinders and calipers.

[JohnnyK]

The benefit of using POR 15 (or another product like it) is that you don't have to remove every last bit of rust. POR 15 encapsulates the rust so it can't spread.

That's marketing BS. If you think a catalyzed product doesn't 'encapsulate' (to use the name of another POR15 style product) as well a single component product, I would be interested in hearing why. POR15 is easy to apply, is available, is affordable, can be brushed on, and works about as well as an alkyd product. Those are it's benefits, not it's 'superior' performance.

[DrWin]

There are quite a few different ways you could go with repairs. POR-15 rust preventative paint is a common fix, or you could strip the panel completely to bare metal and have it powder coated. For the repairs to the frame itself you probably don't want to completely remove it and strip it down for powder coat, so spot repairs are usually the way to go.

My fuel tank closing plate wasn't quite as rusty as yours, so I used POR. The process involves quite a bit of prep, but basically it goes like this:

Remove all flaking epoxy with sanding discs / wire wheel. Feather the edges to avoid hard lines between the existing epoxy and the repair.
Remove rust from bare metal using sanding discs and wire wheel.
Apply POR Metal Ready Etching solution
Apply POR Rust Preventative Paint
Apply POR Primer (This will allow a top coat to stick to the POR rust preventative paint. It will also build up the paint thickness to match the OEM coating)
Apply Top Coat (Rustoleum Smoke Gray is a good color match)

This thread may also be helpful, and there are more pics of repairs on the frame itself.
http://dmctalk.org/showthread.php?51...lor-Comparison

There are other products besides POR that are more user friendly and require less prep, and are easier to top coat. Rich_NYS is in the middle of similar frame repairs and you can see his thread here:
http://dmctalk.org/showthread.php?17...rage-find-quot

He's using a product called Mastercoat instead of POR-15

Damn, that lookes nice.
I'll have to go do that...

[DrWin]

Also, the source of all that damage is a leaking brake master cylinder. Brake fluid softens up the epoxy causing it to flake off, then water gets in causing rust. Looks like you'll need to replace the master cylinder, and your brake servo (booster) is also looking like it suffered some damage from the leaking brake fluid. Unless it has holes rusted through it causing it to leak, you can probably just clean it up and repaint it black.

Great to point that out. I read that brake fluid eats the epoxy. Makes sense that this would be the reason for all that rust in the particular place.

[David T]

It isn't so much that brake fluid "eats" the epoxy as much as it softens it up and allows it to come loose from the metal. When it drys, it cracks and moisture can now get to the steel and the loose epoxy holds the moisture in keeping the area wet as it rusts. That is why part of the fix is to remove as much of the loose epoxy as possible. The other problem with the epoxy coating is that after many years it hardens and in certain, highly stressed areas of the frame where it flexes, the epoxy cracks, again allowing moisture to get to the steel underneath. The epoxy coating was not meant to last forever and when it fails the steel underneath rots.

[Rich_NYS]

I'm working on my 3rd DeLorean. I have the frame stripped and doing spot repairs. I wanted to go with an epoxy finish and got some good advice from Mark D, but my schedule & "piecemeal" approach wasn't a good fit for the process. I also learned of possible compatibility issues with some of the products I already have (and wanted to use,) so I decided on a urethane product.

I used POR-15 on my last car and got very good results. I'd be willing to use it again, but I think there are better products now. I recently learned about the Mastercoat line of products, their Rust Sealer is what I'm using. My friend Jimmy used Eastwood's Platinum rust encapsulator. It's advertised as being 3x better than their regular stuff. I had intended to use that, but forgot about it until after I ordered the Mastercoat. I very strongly suspect it's nearly the same stuff, and definitely choose it over POR-15. I wish I had remembered, 'cause I need to order some stuff from Eastwood and would've saved on shipping.


I'll update my thread soon(referenced above) with pics of my test pieces.


My closing plate was a bit odd; the epoxy had a small bubbled area [that I'm familiar with] on the tank side, but almost all of the epoxy was lifted from the metal (not just the bubbled area) and peeled off in large pieces:


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