I would not use any type of spray foam

Why not?

it could be a potential fire hazard as the cats are under the foam.
I have not tried to burn the foam thats part of the original assembly but i would guess that it must have some kind of heat or fire retardant incorporated in it,
you should figure that the TT will be running in the area of about 200 to 300 degrees F or more .
If you put a solid foam in there this can also cause other issues remember that the TT / drive line moves when the engine is running adding a solid portion to this may transfer NVH to the chassis

If I do it, I'll use flame retardant foam. I only plan on using enough to fill in the crack in the front/center of the factory foam piece.

Maleficio, keep us advised - I am having the same issue with my 83 928S A/T at 63,300 miles...

Will do. I bought a can of DAT foam today, but I may keep searching for a true flame retardant foam for this project.

The motor mounts are filled with water that leaks and they collapse.
Every single car I've found has had collapsed mounts.
The foam doesn't decompose much (unless rodents damage it).

If heat is entering the switch area, as Stan said over a month ago, whether you like it or not, whether you have 30K miles or 130K miles, you need motor mounts to stop the heat.

Will help with driveline sounds and rumble as well.

I've also had one new set of aftermarket mounts fail and need to replace them with the new V8 Volvo mounts during the next couple weeks. How did I know? The heat was back, which prompted a look. Pan bottom should be at a higher level than crossmember. The V8 Volvo mounts are water filled but appear beefy and adequate and have good reviews on the 928. The porsche motor mounts are prohibitively expensive for me.

Not dissing your foam-fill per se, just don't shortchange your driving experience and put undo stress on the driveline by ignoring the harder-to-approach MM issue. If your car has original mounts, they need replacement.

Thanks for the feedback, Chris.

What's really strange is that the heat comes and goes, as if an HVAC valve is opening and closing in the lower forward area of the center console. Sometimes searing heat will barrel out the center console, as I've got the side panels removed.



My mounts are solid, and they look okay, but I'll check again this week.

mine goes like that too some days searing heat barrelling out at front side small gap at shifter leather edge where it meets console. and then days and days nice and cool. way way more cool days than hot ones but when hot atrocious.

Thinking about it seems its when ive turned car on and didnt leave quicker i got back out to do something/s -forgot, had to answer to,or checking something .

like a flapper/valve has reached a temperature and stayed open keeping a heat cycle/build up going and not countering with cool or closed flapper/ valve .

Thinking more, ouch!, theres days, far and few , dont know if same as the hot air days but when turn pcar off a pressured short hiss happens seems at footwell pass side under glove box.
I do know hvac hasnt been completely worked out so no surprise really. hiss hiss already lol