Summary:
In December, 1999, I decided to spend some of my Christmas break from the office  working on a carburation problem on my 1969 912/5.  In the process I found that debris from the original sound deadening insulation in the engine compartment were being sucked into the air cleaners, and cooling fan.  I suspect that they were probably also blocking the oil cooler and resting on top of the cylinders interfering with cooling. Like every other project I initiate on my 40+ year old sports car, the scope of the project was expanding (as if my magic) to consume my entire Christmas break and more financial resources than originally planned.

Replacement of the insulating pads, called a damper by Porsche, was straightforward but considerably more time consuming than I originally anticipated. Based on the amount of debris blocking the cooling air passages, and jammed into the oil cooler, I would strongly suggest that this repair be completed if you have any evidence of deterioration of the insulating pad. Schedule 16 hours over two days to perform the entire task, and return the car to driveability.

The following procedure is intended to guide the experienced enthusiast / mechanic in these tasks. I do not guarantee, in any way, that these are comprehensive, foolproof instructions. Read them and use common sense, and you should be able to complete this task with a minimum of grief and consternation.

Gotchas:
While theoretically possible, I do not believe that this job can be done without removing the engine from the car. The risk of damaging delicate wiring and linkages is far too great to justify the attempt.

Only the large overhead and forward damper is available pre-cut. You will purchase two dampers, use one intact for this replacement, and cut the other to make the left and right sides. You would like to remove one of the sides intact (mine disintegrated) to use as a pattern. They are mirror images of each other, so one "pattern" can be used for both sides.

Adhesives only work well if the temperature is above 60F. Don't try this if you cant get the car up to this temperature for the duration of the project.

Tools:


Procedure:

  1. Disconnect the battery. Remove the engine. If you haven't done this before, it will take you approximately 3 hours. If you have, you should be able to get it done in less than 1 hour. Do not let this task scare you, it's fairly easy for one person to do. For details, check the archives or post an inquiry to the list.

  2. Open the metal tabs holding the wiring along the right and left sides of the engine compartment. Free the wiring from the tabs. Using dikes, cut any wire ties that secure clusters of wires to each other so they are free. You don't want to ding the wires while you're scraping off the old pads.

  3. Immediately forward of the voltage regulator there is a cluster of ground (brown) wires secured to the body of the car with a 13mm nut. This "common ground" is nearly impossible to see if the engine is in the car, and probably hasn't been disconnected or cleaned in 30 years. Spray this with liquid wrench, remove the nut and wires.

  4. Verify that the battery is disconnected (Very Important). On the left (driver's) side, remove the two 10mm nuts holding the voltage regulator and relay panel in place. There are through bolts on these, which are accessible from inside the left fender which also have 10mm heads. Pull the relay panel and regulator free. Again, it should not be necessary to disconnect anything.

  5. If you have an electric rear window defogger, find it's wires near the left hinge of the engine compartment door. Follow these wires to the relay panel, and disconnect them. If you have "fresh air" rear window defogger outlets, there may be one or two hoses to disconnect. I don't, so I'm not familiar with how they are configured.

  6. Bend the tabs holding the old insulation pad to the top, left and right of the engine compartment. If you're lucky, most of the pads will fall out, making a huge, dusty mess. If you're not lucky, you get to begin scraping and heating to get the old pads off. If possible, try to get either the left or right side in one piece. You would like to have it for a pattern. Using a strong household cleaner, wash down the areas where the old pad was previously attached.

  7. Make a pattern of the right side using cardboard. Check and recheck the fit of the cardboard in the engine compartment. With the pattern in place, write the word RIGHT on the pattern. The right and left panels are mirror images, therefore one pattern can be used for both right and left sides. Turn the pattern around, and fit it to the left side of the engine compartment. It should fit properly. With the pattern in place, write the word LEFT on the pattern. Mark the pattern for the four holes required on the left side for the ground stud, voltage regulator mounts and relay back-plug.

  8. Place one of the new dampers on a flat surface, foam side down. Using the pattern you have created, outline one RIGHT and one LEFT. Pay attention; Remember, you are working with left and right sides here. It is possible to get both the left and right sides out of one damper. There will be some holes where the large damper has been pre-cut for wires and hinges. We'll worry about these later. Carefully cut out your new left and right pads.

  9. Test-fit the left and right pads without adhesive. When the pads fit to your satisfaction, wipe the engine compartment walls with lacquer thinner. It is important that the surface is clean or the new pads will not bond properly.

  10. Turn on your fan so that fresh air is blown into the engine compartment. You don't want to be trapped in that small space with adhesive fumes. Using the paintbrush, apply adhesive to the right engine compartment wall, and to the new right damper pad. Follow the instructions on the adhesive; You want the adhesive to be dry enough that it will hold the pad in place, but not so dry that you cannot adjust the pad during assembly. Once you have the pad in place, gently hold it there. Don't squish the pad, or the adhesive will soak into the foam and your handprints will be permanently embedded in your new insulation!! It can take as long as 10 minutes (and get pretty uncomfortable) holding the pad before it stays in place.

  11. Do step 10 on the left side, then take a break for at least 1 hour to let the adhesive set-up.

  12. Test-fit the large damper pad to the top and front of the engine compartment. Find the rear-window defogger wires (if applicable), and pass them through the hole in the damper pad. Remove the damper pad and apply adhesive to the foam surface of the pad, and to the engine compartment surfaces. Follow the instructions on the adhesive; You want the adhesive to be dry enough that it will hold the pad in place, but not so dry that you cannot adjust the pad during assembly. Once you have the pad in place, gently hold it there. Don't squish the pad, or the adhesive will soak into the foam and your handprints will be permanently embedded in your new insulation!! It can take as long as 15 minutes (and get really uncomfortable) holding the pad before it stays in place since you're working in opposition to gravity on this one.

  13. In order to insure a good bond between the pads and engine compartment, you need to apply pressure to the pads while they dry. I did this by building a temporary platform across the engine compartment, then a large, inflatable dinosaur (sometimes it's nice to have small children) on top of the boards. I then inflated the dinosaur, which complete filled the engine compartment, applying gentle pressure to all of the pads I had just put in place. You are now done for today. You may want to check your dinosaur to insure that it is still properly inflated occasionally.

  14. Deflate your dinosaur and admire the nice job you have done!! From the pad scraps, cut out appropriate pieces to fill in any unwanted holes or squares on the side panels (as noted in step 8). Glue them in place with the contact adhesive.

  15. Use the adhesive solvent to remove any unwanted adhesive from your finished installation, and some general purpose cleaner to clean the newly installed pads.

  16. Re-connect the rear window defogger (if applicable). Re-install the relay panel and voltage regulator.

  17. Using steel wool, carefully clean the electrical ground stud until it is bright and shiny. Clean the ring connectors on the brown wires, and loosely install the brown wires on the stud. Spray the cluster of connections with WD-40 or similar, and tighten the nut, being careful not to unnecessarily crimp the wires.

  18. Guide the wiring loom back behind the metal clips and secure all loose wires with wire ties along both sides of the engine compartment.

  19. Before re-installing the engine, I strongly suggest that you remove the fan shroud and remove any debris from the oil cooler and cylinders. 

Regards to all,
Jon B Kanas


kanas@qadas.com