THE WHY?
The benefits of installing new sound absorber to the underside of your hood / bonnet are reduced noise. It also keeps the heat inside the engine compartment preventing damage to external paintwork and keeps the engine at the optimal operating temperature aswell as insulating it from the sun and snow.
THE TASK
Before you can start you will need to remove all the old sound absorbing material, see my other post for a how to. This is very important as poor preparation could end up costing you a lot of money.
You will then need the following items:
a. Methylated spirits
b.Wax paper or baking parchment
c. 3M Scotch Weld 80 Spray Adhesive (£15)
d. Scalpel
e. 2 x sound absorbing pads from Porsche or here (£30-40 per side)
f. Large sheet to cover engine bay
g. Masking tape
h. Old newspapers
THE HOW TO
(Amateur mechanic Job Time approx: 1-2 hours)
As stated above you should have completely cleaned the old sound absorbing material from the underside of the bonnet /hood. If not see here for a how to.
Now begin by covering the engine bay with a large sheet, this will prevent any glue getting on the engine. Next use newspaper and low-tac masking tape to mask off one of the sound absorbing areas as shown below.
Give the exposed area a quick wipe over with methylated spirits to remove any grease, allow a moment for the meths to evaporate. Now depending on what sound abosrbing material you've bought the process here may differ. If you've bought genuine Porche sound absorber I believe it has it's own adhesive backing. If like me you bought 3rd party sound absorber you will need to use a special heat tolerant spray adhesive called 3M Scotch Weld 80. Spray the exposed area giving it a generous coating, then tear off two large sheets of wax paper / baking parchment and stick these over the glued area (as shown below) making sure you leave about 2-3 inchs of exposed glue along the top edge.
Now pick up the corresponding sound absorbing pad and coat the back of the pad in the same 3M adhesive. Once you've done this take the top edge of the pad and carefully line it up in the correct position and stick it to the underside of the bonnet. This glue is not repositionable so precision is the key here. Once you are sure you've got it lined up correctly remove the upper most sheet of wax paper and carefully smooth down the pad making sure you massage any air pockets out to the edges. Then remove the lower sheet of wax paper and smooth the final piece down. You may find that the bottom edge overlaps the area, but before you trim it make sure you remove all the surrounding masking tape and newspaper. Now simply trim off any excess with a scapel and press down all the edges. If you've got any bubbles use a pin to make a smal hole in the centre of the bubble and massage out the trapped air.
Now the finshed article with transfers applied
The benefits of installing new sound absorber to the underside of your hood / bonnet are reduced noise. It also keeps the heat inside the engine compartment preventing damage to external paintwork and keeps the engine at the optimal operating temperature aswell as insulating it from the sun and snow.
THE TASK
Before you can start you will need to remove all the old sound absorbing material, see my other post for a how to. This is very important as poor preparation could end up costing you a lot of money.
You will then need the following items:
a. Methylated spirits
b.Wax paper or baking parchment
c. 3M Scotch Weld 80 Spray Adhesive (£15)
d. Scalpel
e. 2 x sound absorbing pads from Porsche or here (£30-40 per side)
f. Large sheet to cover engine bay
g. Masking tape
h. Old newspapers
THE HOW TO
(Amateur mechanic Job Time approx: 1-2 hours)
As stated above you should have completely cleaned the old sound absorbing material from the underside of the bonnet /hood. If not see here for a how to.
Now begin by covering the engine bay with a large sheet, this will prevent any glue getting on the engine. Next use newspaper and low-tac masking tape to mask off one of the sound absorbing areas as shown below.
Give the exposed area a quick wipe over with methylated spirits to remove any grease, allow a moment for the meths to evaporate. Now depending on what sound abosrbing material you've bought the process here may differ. If you've bought genuine Porche sound absorber I believe it has it's own adhesive backing. If like me you bought 3rd party sound absorber you will need to use a special heat tolerant spray adhesive called 3M Scotch Weld 80. Spray the exposed area giving it a generous coating, then tear off two large sheets of wax paper / baking parchment and stick these over the glued area (as shown below) making sure you leave about 2-3 inchs of exposed glue along the top edge.
Now pick up the corresponding sound absorbing pad and coat the back of the pad in the same 3M adhesive. Once you've done this take the top edge of the pad and carefully line it up in the correct position and stick it to the underside of the bonnet. This glue is not repositionable so precision is the key here. Once you are sure you've got it lined up correctly remove the upper most sheet of wax paper and carefully smooth down the pad making sure you massage any air pockets out to the edges. Then remove the lower sheet of wax paper and smooth the final piece down. You may find that the bottom edge overlaps the area, but before you trim it make sure you remove all the surrounding masking tape and newspaper. Now simply trim off any excess with a scapel and press down all the edges. If you've got any bubbles use a pin to make a smal hole in the centre of the bubble and massage out the trapped air.
Now mask up the other side and repeat the process.
Now the finshed article with transfers applied
Here is a link to the 3rd party manufacturers instructions in case you are still unsure or need further detail.
this is really neat and looks really look my Boy friend has a Porsche 944 that he bought a year ago i might show him this it looks neat
ReplyDeleteI followed your instructions did the same to my 944 type 2, here in Holland. I ordered the Pads on EBay.
ReplyDeleteWe started en finished the job in a day, but we had to work hard. The Porsche glue is really difficult to remove, and you are working in an awkward position too.
But a lot of alcohol (and a lot of sweat) did the job.
Getting the pads on the car, after removing the glue was easy. I am still satisfied when I look under the hood.
Thnx for posting!
A.L.C.C.M. Bik
Glad you found the guide useful, it's not an easy job. If someone has a better way of removing the old glue I'd love to know. But the finish when you stick the new pads on is well worth it.
ReplyDeletemy '87 has a hole for the brake fluid reservoir cap - is that poking into yours?
ReplyDeleteNope, it doesn't touch it. The only bit that does touch very slightly is the end of the injector rail nearest the distributor cap, not enough to make a hole just a small dent in the material. Really pleased with the work I did on this, still looks as good and is stuck as well as the day I did it almost 3 years ago now. Where did the time go :)
ReplyDeletedo you think the material would be easy to cut?...
ReplyDeletedid your original have a hole there - or anywhere else?
Yep, material would be very easy to cut, probably best using a template and a sharp scalpel. The original sound absorbing material had completely vanished before I acquired the car, if you look carefully in the second picture in the other how-to I did on removing all the old glue you can just make out the circular area you describe that would sit over the brake fluid cap. I didn't have the original stuff to work from so was none the wiser when I originally did this job. As I said earlier it only touches the injector rail very slightly on mine, not enough to warrant cutting a hole for in my opinion.
ReplyDeleteWould it make sense to add a layer of Dynamat (or comparable sound/heat proofing material) to the underside before installing the factory-type sound absorber as you did? Anyone try that?
ReplyDeleteI don't see how that would be of any benefit having two layers? The 3rd party solution I used already insulates against noise and heat, it is also flame retardant too. If you applied two layers you would also probably need to cut some areas to stop the material pressing against the engine when the bonnet is closed as the gap is quite tight in some areas.
DeleteWhere did you get the transfers from?
ReplyDeleteThey came from the same place as the pads, see the link in the list at the beginning of the article. Not sure if they sell the transfers separately though.
Delete