Hi,
I thought I'd share my recent experience of replacing the worn out original liner. My "˜86 turbo came with the dimpled grey sponge bonnet liner. Over time this became brittle and began crumbling onto the engine.
I scraped off the sponge and used glue remover, a solvent, to remove the residual rubbery type glue. I spent 4 hours over several sessions spraying on the solvent then quickly following up with a plastic scraper. It was really hard work, especially since I decided to leave the bonnet in place. Eventually I got the bonnet almost to bare paint, but with smears of glue pretty much everywhere. I was not prepared to continue the torture and so decided I would line the bonnet.
Research suggested that Classic 9 Leather Shop's replacement liners were decent quality and fit. The material is:
"nitrile vinyl closed cell foam rubber, these hood liners will not absorb water or oil. They are light, about 11 ounces on average, are fire retardant and insulate against sound and heat.
You can wash the liner and hose it off. Since the material is made for aircraft firewalls and bulkheads and is FAA approved for aircraft, it's extremely light and unlike the factory liner will not absorb water and resists mildew."
I opted to not have the large white Porsche emblem on the liner. I chose the ½ as opposed to ¼ inch thick option. It cost about £90 including VAT and import from her US.
The material appeared to be carefully hand cut using a template. It was certainly not cut with a press tool as a factory part would be, the fit was pretty good, but not perfect.
I tested a small off cut of liner material and my chosen glue (Evo Stick Impact Adhesive) on a piece of painted steel plate. After the glue had gone off I set about the test piece with a cigarette lighter. No fire, good news.
I lashed generous amounts of glue onto the two pieces of liner (3 x 250ml in total) then offered it up to the bonnet. It's worth spending some time pressing the liner to expel air pockets and to follow the swage line pressed into the bonnet.
Once in place do not drive the car. Leave it for a few days to make sure the glue has fully given off its solvent and set.
If you do drive the car before the glue has set the heat from the exhaust will evaporate the solvent so quickly that it can't defuse through the liner fast enough. The liner will then balloon up and stretch. You will then have to quickly drive to B&Q to buy more glue, remove the liner, re-trim it to make up for where it has stretched, then re-glue it in place. Ensuring your car is located in a place where you are happy to leave it parked up for a couple of days. Well, at least that's what I heard happens if you drive the car before the glue has set, ahem, moving on.
The ½ inch liner does touch several components in the engine. This results in permanent indentations in the liner. I can't say if the ¼ inch liner avoids this issue.
The car now sounds slightly quieter. The higher frequencies emanating from the engine bay are the ones most attenuated. Imagine turning the tone control on your stereo so that it dulls the sound. It makes the car sound a bit more refined.
I'm happy with the end result.
I thought I'd share my recent experience of replacing the worn out original liner. My "˜86 turbo came with the dimpled grey sponge bonnet liner. Over time this became brittle and began crumbling onto the engine.
I scraped off the sponge and used glue remover, a solvent, to remove the residual rubbery type glue. I spent 4 hours over several sessions spraying on the solvent then quickly following up with a plastic scraper. It was really hard work, especially since I decided to leave the bonnet in place. Eventually I got the bonnet almost to bare paint, but with smears of glue pretty much everywhere. I was not prepared to continue the torture and so decided I would line the bonnet.
Research suggested that Classic 9 Leather Shop's replacement liners were decent quality and fit. The material is:
"nitrile vinyl closed cell foam rubber, these hood liners will not absorb water or oil. They are light, about 11 ounces on average, are fire retardant and insulate against sound and heat.
You can wash the liner and hose it off. Since the material is made for aircraft firewalls and bulkheads and is FAA approved for aircraft, it's extremely light and unlike the factory liner will not absorb water and resists mildew."
I opted to not have the large white Porsche emblem on the liner. I chose the ½ as opposed to ¼ inch thick option. It cost about £90 including VAT and import from her US.
The material appeared to be carefully hand cut using a template. It was certainly not cut with a press tool as a factory part would be, the fit was pretty good, but not perfect.
I tested a small off cut of liner material and my chosen glue (Evo Stick Impact Adhesive) on a piece of painted steel plate. After the glue had gone off I set about the test piece with a cigarette lighter. No fire, good news.
I lashed generous amounts of glue onto the two pieces of liner (3 x 250ml in total) then offered it up to the bonnet. It's worth spending some time pressing the liner to expel air pockets and to follow the swage line pressed into the bonnet.
Once in place do not drive the car. Leave it for a few days to make sure the glue has fully given off its solvent and set.
If you do drive the car before the glue has set the heat from the exhaust will evaporate the solvent so quickly that it can't defuse through the liner fast enough. The liner will then balloon up and stretch. You will then have to quickly drive to B&Q to buy more glue, remove the liner, re-trim it to make up for where it has stretched, then re-glue it in place. Ensuring your car is located in a place where you are happy to leave it parked up for a couple of days. Well, at least that's what I heard happens if you drive the car before the glue has set, ahem, moving on.
The ½ inch liner does touch several components in the engine. This results in permanent indentations in the liner. I can't say if the ¼ inch liner avoids this issue.
The car now sounds slightly quieter. The higher frequencies emanating from the engine bay are the ones most attenuated. Imagine turning the tone control on your stereo so that it dulls the sound. It makes the car sound a bit more refined.
I'm happy with the end result.
