Hi, I removed the foam out of the rear trunk lid last week. Nasty job but managed to do so. Some rust inside and some pinch holes coming through. See pics below.

Used all kinds of tools to get it out (bugger of a job!)
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Used Brunox to neutralize rust inside
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Cleaned the centre piece first with Rustyco (rust remover) and blasting afterwards
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Stich welding trying the get it as flush as possible
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Started to weld up, still some grinding to do...
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good job

@dt4 Thanks... I see you have a 1.8 also. Are you planning to run the L-jet again or go carbs? Mine wasn't running when i bought is (broken valve ). So now at the mechanic for rebuilt.

Nice work!
Good to see a fellow dutchy here.

@kroelofsen
Mine came over already running on carbs so I don't have the original FI set up.

It is running but I haven't had it on the road so I don't know how well it is running.
Dylan (chi-town) took it on the West Coast run last year so it will be pretty well set up

I had an Audi UR quattro (1984) a few years ago which was K-Jetronic FI and I couldn't get that to idle properly so I am not too disappointed that it doesn't have FI

Is the foam along the whole rear edge or only in the middle section, and if so, approximately how wide?
Thank you.

On mine, the foam went about halfway to each rear corner.

I cleaned the foam out of my replacement trunk lid (and patched some rust to one side of the latch mount).

Are you planning to replace the foam, or otherwise adhere the internal rib to the lid? The rib on mine seems kinda flexible, and I worry about latching the trunk lid without enough rigidity.

The foam starts in the middle and is aprox. 50 cm wide...

Yeb it is a bit flexible and I’m thinking about a blob of seal seam under it...

Disregard, now that I think about it. Probably wouldn't work. I was thinking you could dissolve the foam, but you couldn't get enough solvent in and out easily without cutting. However may be good to get what you can't dig out easily.

Good work. Foam is an evil moisture trap. There are a few other places in 914s.

Don't disregard. Acetone can dissolve that shit and wash it out.

It took me around 4 hours to clean both sides. I used special diy tools, see pic.

Basically I used a chisel on an extension, wire brush same and a 2mm wire with a hook bend on the end to jank the foam out bit by bit.

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Cleaned up pretty well... Afterwards it was soaked in rust killer. Lets hope the rust will stay away for a while...

Can you test the foam and see if acetone will dissolve it?

One more reason I'm considering a fiberglass or better yet, carbon lid for my car

Yes. Please try acetone.

Carb cleaner will dissolve it

Hi guys, sorry don't have acetone...

Finished welding and grinding and put some primer on it. Now only the lip needs to be welded in place.

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Wow, great job on seamlessly fitting that replacement sheet metal, looks fantastic!

As a test, try your girl's nail polish remover on a piece of it. Basically the same thing (at many times the cost (in more than one way) LOL)

It it works you only need a drop to tell.

It it for the win! Hence my reply. Well, while at it, line up a few pieces and drop on several different chemicals on each. Time lapse it so we can watch the difference between acetone, carb cleaner, Oshpo (lol), etc.

Oshpo (hydrochloric acid) is a rust killer, won't hurt steel, and what are your guesses at which would dissolve foam most? Hmm. No, I'm not suggesting this. Consult with your lawyer. Lol. Interesting to hear what other thoughts come up.

Ospho is mainly phosphoric acid, not hydrochloric. Hydrochloric acid happily eats steel, whereas phosphoric likes rust and leaves a phosphate coating. Unfortunately, I don't think Ospho would do much to the foam.

Wow, there are a few of us working on the same thing lately.. this is from a few days ago. The following picture shows a left & right side foam piece from two different trunk lids.. I used brake cleaner to dig the other side out of the trunk I've decided to keep and use. The brake cleaner certainly did not "dissolve" any foam, but it might have made the digging quicker (with a very long narrow flat tip screw-driver). I poured a little acetone on one of the foam pieces below after I took the picture - it had no effect what so ever.

My bad. Good catch. I knew it was phosphoric - it's in the name.
I'd still like to see what it does to foam.

Well, I have some Ospho. If someone wanted to send me a chunk of that foam, I can try putting some Ospho on it and will report what happens. Although, TBH, I really don't think there will be any reaction, except maybe to clean the rust off the foam.

Acetone will not melt polyurethane foam but it melts polystyrene foam in seconds.

What was Porsche's reason for the foam in those areas?