Engine Bay Cover - Foam Insulation Disintegrated

987 Crew, I popped the engine bay cover off - for the very first time - to do some maintenance and discovered the engine thoroughly covered in dust from the dry-rotting, crunchy foam heat/sound insulation pad on the bottom of the cover. Complete mess - it turned to powder with almost no force. Searching the google-webs, I haven't found a 987 specific replacement for sale. Not much on this forum either (unless I'm using all the wrong search words). What is a good substitute? I'm leery of using a typical sound-deadening mat for fear it will melt or peel away from the lid onto the engine. I don't want to leave the lid "uninsulated" as I suspect the insulation helped protect the carpet from thermal damage. Thanks in advance.......

Hey @Tytanium , Wow, finding your engine covered in that crunchy, disintegrated foam dust must have been a messy surprise! When you were searching for substitutes, did you happen to come across any specific heat-resistant materials, even if they weren't made specifically for the 987? Sharing what you've already looked at might help the crew here suggest a good alternative that won't melt.

A quick search came up with many options for your application. Below is an example of one of these products. A Google search for ’automotive sound deadening and heat insulation‘ led me to many results, with A****n carrying many in that category. My only caveat is to read the specs, reviews and details to ensure that it is heat resistant. Many of these choices are typically ‘sound deadening’ centered, make sure you choose one that is truly heat resistant. And beware that there is a large price range between these products. Don’t go cheap. That will only get you a cheap made in China knock-off that will break down quickly over time. Spend the money for a good quality matting that will perform well, and last long.

Mine was little more than dust also. Like you, i did a lot of searching. What I ended up with was putting closed cell foam on the other side (away from the engine) and it has definitely helped with the engine noise. I did this on both engine covers.

WTFChuck & ForaFrank, Thanks for the replies. I looked at many (if not damn near all) of the "heat-resistant" sound matting, with the vast majority being either foil over butyl (gooey) or foil over polyethylene (PE) closed cell foam. NONE of them are rated for continuous heat and thermal cycling at the 1100-1800°F temps the headers kick out. None of these products has ASTM heat-related specifications. Even if they did..... there's a huge difference between ASTM lab results and real-world long-term applications. Looking at reviews and specifications (for hours and hours), many users report heat-related adhesive and material failures across all brands. Just this past Sunday, I exposed Kilmat (top brand) and the Amazon Basics equivalent to a small household space heater I use to heat the bathroom on cold mornings - the butyl matting turned rather gooey. I also looked for the Porsche OEM replacement online - nothing found, but I plan to stop by a dealership. SoundSkins has a "Heat Shield' product rated to 480°F, which is a touch less than the header temps of 1100-1800°F. What I did do - I covered the EXTERIOR/top of the engine bay cover in 80mil foil over butyl Kilmat. I used aluminum tape to ensure no sticky butyl edges are exposed. I'm certain the noise has been dampened, but I remain concerned that the mere 80mil thick material will have little heat shielding capabilities. I'll take pics and post soon - turned out nice. Under consideration is a high-temp adhesive to attach a cut-to-fit welder's blanket (or pieces) with foil on top. Search Amazon for "Kanhiro Carbon Felt Welding Blanket Fireproof" - a couple of different options if you're interested. Why so hell-bent on solving for both heat and noise? The Infantry and Aviation left me with significant hearing loss & hearing aids (way too young). I'd like to protect the car and my ears. Still open to ideas ................ Thanks, Tyler

This is great. Thanks for the pic. I have a box of Siless 157mil (4mm) Closed Cell PE Foam. What are the specs of what you used? Depending on my results with the 80mil Kilmat, I might consider a layer of the 4mm PE where space allows. v/r, Tyler

@Tytanium My Cayman is only two years newer than yours but I've got 4 times the mileage and it spent most of its life in Florida heat. The foam under my top engine cover is as good as new. Maybe slightly discolored due to age. I wonder if your engine compartment fan is working to prevent excess heat buildup. BTW, the foam shouldn't need to handle 1100-1800°F header temps. That heat is localized at the lower sides of the engine. I'm sure most of the non-metal parts in the engine bay wouldn't handle that heat either. I would expect 300-400°F would be sufficient. It might be interesting to put a barbecue thermometer heat probe under the cover and capture the actual heat values you're dealing with.

Wonder if they changed material. My 2012 seems to be in good shape. (Fingers crossed) If I had to replace it and could not find an OEM piece, I would probably start with some fairly high density rubber foam sheet (Maybe 1" thick) and sandwich it with a self adhesive rubber/aluminum sound/thermal insulation sheeting (Maybe 1/4" thick). This pieces are INSIDE the car, and don't touch the exhaust at all. I would bet they never get to 200 deg F.

I have another idea on why insulation foam on some covers is deteriorating. Maybe someone attempted to clean it with an improper cleaning product. In my case I don't recall ever doing more than (very rarely) wiping it with a damp rag

My thoughts exactly, as I pondered this issue. If, as it sounds, the OP is referring to the engine cover which sits horizontally over the engine, it is nowhere near enough to the headers to be exposed to those extreme temps. Looking at the engine, there are plenty of plastic bits and soft rubber lines that would have melted a long time ago if they were exposed to temps of 1100-1800°. And if he is referring to the vertical panel behind the seats, I’m sure the temps in that location are nowhere near those extremes. The serpentine belt is directly behind that cover and I doubt it would withstand temps in that range also. A lot of the sound deadening/insulating material I reviewed online specifically indicated that they were for engine bays, underhood, and some marine engine box applications. Besides, the low cost of these would lead me to at least attempt a fix, then with monitoring the material over days and weeks, determine if it is failing, and removing it before it any problems arise. At such a low cost fix, finding out it is not suitable is not a big hit to the wallet.

I recently removed the front engine cover (the panel behind the seats) to discover the same disintegrating foam problem. Again, crumbling to powder. Quick trip to Porsche , Boblingen to learn replacement foam mats cost almost 500 and 900 euros for the front and top lids, respectively. The service guys confirmed what I already knew - thermal cycling over the years destroys all of them, and they never replace the mats once they are ruined. I removed the mat residue from both the top and front covers. The Kilmat significantly cuts down engine noise in the cockpit. Next step: This same crumbling OEM foam matting partially lines the front and sides of the engine compartment. I intend to remove all of it. I will apply Kilmat to the cockpit side of the firewall (behind the seats). Some pics of the front cover (pre & post) to follow.

The foam has a top layer that remains somewhat intact. But the foam core is dry and has lost all beneficial physical properties. The core crumbles to dust with even gentle handling.

Just pressing my fingers into the foam destroys it - note the finger indentations.

And the finished front engine cover. The top engine cover looks very similar. 80mil Kilmat cut to form and finished with aluminum tape on the top side (not the engine side). The correct heat (>70F) and use of an application roller were key to success.

I did confirm the engine fan on the right side of the engine bay is working as one might expect. I cannot speak to the cleaning chemicals used by prior owners between 2008 and now (17 years), so I can't rule this out as a contributing factor. That said, between the dealership having specific knowledge of this issue - and NOT suggesting customers replace these mats - I think it's safe to assume the root cause is thermal cycling over the years. v/r, Tyler

I've been confused by your foam disintegration issue. As I stated earlier, I've seen no such issue. I don't recall any other members having this problem. So I doubt is it common. I'm also confused by your photos because there should be no foam insulation on the aluminum cover. Here's a video showing both the removal of a 987.1 firewall cover (behind the seats). Here's another video showing the rear deck carpet and cover removal. In both cases you can see the carpet has thick beige colored insultation attached to the underside. Also see that there is absolutely no foam insulation on the either of the aluminum covers(inside or outside). Only some rubber weather seal underneath around the perimeter to prevent air/water intrusion around the covers. Since there is no way the under-carpet foam insulation could reach the actual engine bay with the aluminum cover installed, I am wondering if your car had some additional insulation added by a 3rd party. Your photos seem to show the firewall cover (as best as I can tell with the extreme close-up) with disintegrating foam that shouldn't be there. So maybe what the 3rd party installed is disintegrating? If so, no expensive Porsche replacement will replenish that foam. Is the foam attached to the underside of the carpet destroyed, or not? That foam is sort-of rubberized. It has very little contact with engine generated heat. So I doubt heating/cooling cycles are the culprit.

RSchwerer, Please read my posts more carefully. The disintegrating foam is on the engine-side of the engine covers and the engine-side of the engine bay. I never said anything about the foam on the back side of the carpet - neither do my pictures show the beige foam on the backside of the carpet. The foam mats throughout my thread are OEM parts - complete with OEM PNs and prices - that are clear in the OEM service manual. Check this vid at about 4:30 Video @ 4:30 In fact, you can see some dusty powder fall from the foam mat on the underside of the engine top lid in the video at 4:50 when his thumb touches the crumbling foam.

Here's a video that shows the mat on the engine's front cover Video @ 2:45

I wonder if that insulation is only for certain localities? Checking lots of videos, I found it hard to find ones that clearly show the underside of the cover(s). My engine cover is like this guy's, which is just bare metal on the engine side. Same with the firewall.

I think the confusion may be between the tank urethane foam behind the carpet, and the black foam attached to aluminum covers.

I looked up the engine cover in PET and Googled that part. Here's a used one for $180. 2006-2012 Porsche 987 Cayman Engine Cover Trim Panel / 98751321101 Also on ebay for 129 EUR Genuine Porsche Cayman 987 Engine Bay Cover Engine Aluminum 98751321101

@RSchwerer - That could be. My car is EU spec, and the dealer that advised me (Boblingen) is a suburb of Stuttgart, DE - so maybe spec'd for EU and not USA 987s. And I do see more US-based vids where there is no foam on the top cover. @wwexell - Is your car EU or US spec? I also wonder if, due to "failing", dealers removed the pads over the years. I have this padding/matting on the inside of my engine compartment too. Where it is not easy to reach and remove. It is crumbly and rotted as well.

I bought my 2010 new off the dealer's lot in St Petersburg FL. I don't think the dealership modified it. BTW, one reason I looked up the part number in PET is to see if there were any revisions or model variations. There were none. So it's still a mystery why some are insulated and others not

Agree, that is strange. All of the engine covers, both the top (horizontal) and the engine front covers (vertical, behind the seats) that I have seen have no insulation on them. Just a bare aluminum sheet with a rubberized gasket around the perimeter. Yet, watching the vid of the guy detailing his engine shows such insulation in place. Would like to know the mystery as to why some vehicles have it while others don’t.

I have an '09 US spec car with the shitty crumbling black insulation. (~93k miles)

Maybe it is by certain model years? My '09 has crumbling black insulation also.