DIY: Hood Insulation on a 1977 Porsche 924

I love doing these DIY posts.  I doubt there is much need for this one, but I just did it this weekend and snapped enough pictures as I went to put something together.

We bought this 1977 Championship Edition 924 this past winter.  It's in fantastic shape.  If there's a better Championship Edition out there, I'd like to see it.  I noticed that it was missing the underhood insulation that should be on the car though.  The car has clearly been painted, and the insulation was just never replaced.  I ordered an insulation / heat shield kit from Pelican Parts for something like $80.  It's pre-cut foam and is really better than what originally came on the car.  

Here's the problem though - It's just not a job you want to do with the hood on the car.  I'm not saying you can't do it, but I assessed this job and decided it would just be so much easier and produce better results if the hood were off the car.  I hate removing panels from a car that is perfectly straight, but it was the best option here. 

Removing the hood is not that terribly involved.  It's held on by four bolts.  That's it.  First though, you need to remove anything that is connected to the hood and the rest of the car.  In this case that was just the light and the windscreen washer tubes.  The light was simply one screw and plucking a wire out of a couple of clips.  The tube is equally simple.  It just pops out and then you can pull it through the hood until it's free.  I took pictures just to make sure I knew how it all went back in.

As I mentioned, there are four bolts - two on each side.  I believe they were 13mm, and they were easily accessible.  I put painters tape on the edge of the hood just to make sure I didn't scratch anything with the socket wrench.  This is where you need help.  It's at least a two person job, if not three.  I recruited my wife and mother for this one (and my two-year-old daughter - but she was just supervision).  After carefully protecting every inch of paint that was at risk (next picture) we loosened the bolts on both sides and then with my wife and I holding a side each, Grandma removed the bolts. 

 
I used furniture pads and blankets and covered everything that I thought might be at risk.  It turned out to be unnecessary, but better safe than sorry.  The paint on this car is pristine, and I wasn't taking any chances. 

 
I had two sawhorses set up in the back of the garage with pads taped around them so we just lifted the hood over the car and flipped it and placed it gently on the horses.  This hood isn't terribly heavy.  I've laid the insulation pads on the hood to check fitment here.  There was one section (the one that juts out on the left side) that needed to be trimmed, but that was a breeze.  You can cut this stuff with a pair of scissors easily.

The first step is to clean up the hood.  This was almost a non-step on my car, but others that have residue from previous pads and years of engine grease might be a different story.  I used some Goo-Gone to clean up a few minor spots and wiped everything down, but that was all I had to do.  I then taped around the edge of the areas I was going to be spraying just to keep any overspray from the adhesive off of the paint.

It's pretty simple really.  I used 3M Spray Adhesive - the yellow stuff.  I set the mats on some boxes on the driveway.

So here's how this stuff works.  You have to spray both surfaces you're putting together.  I installed one pad at a time just in case I had an issue.  I sprayed the hood liberally in both directions to cover everything and then I sprayed the pad the same way.

You have to let everything sit for between 4 and 30 minutes (per instructions).  It's a little weird letting glue just sit there.  I let it sit for the minimum of four minutes, during which time I removed the tape I had on the hood.

The trickiest part of the whole operation is setting the pads in.  This stuff is really sticky and you can't just slide it around until you get it exactly where you want it.  Once it's down, it's pretty much down.  This is why I think it would be very difficult to do this with the hood on the car.  I got both sides set and then left them for an hour or so.  No issues and they look great.  The trick is to make sure of your fitment before applying adhesive.  If you've got a perfect fitting piece, you can just work from one corner and get it in flat and smooth.

I reassembled the entire crew (after bath time for our supervisor) and we put the hood back on the same night it came off.  I was concerned with getting it lined up but it was really easy and looks like it was never off the car.  I reinstalled the washer tubes and the light and it was job done.  It's a couple hour job, and most of that is prep work and waiting on the adhesive to dry.  If you have to clean off your hood though, it will take much longer.  

This is a DIY job that will certainly improve the looks and functionality of your 924.