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Firewall insulation

Interceptor, SP, FF

by Interceptor3 » Fri Feb 03, 2012 10:31 am

I am thinking about getting some firewall insulation for my car. Is it at all possible to fit with the engine still in the car? My car had insulation on it which was silver foil faced, with a lead? sheet behind that, and then foam which is what glued to the car. The foam has rotten and the sheets pretty much fell off when you touched them, so now I have all this foam stuck everywhere. It goes rather powdery when you rub it with your fingers, and I am not sure the best way to get it off either.

Any advice greatly appreciated.
Nigel Honey
Hobart, Tasmania
'72 Jensen Interceptor Mk3 128/4633
'08 Mitsubishi Lancer Evolution X MR
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by dinofritz » Fri Feb 03, 2012 1:23 pm

Hi Nigel,

Well, I guess that you know that the rubber is a closed cell Neoprene rubber, which can be brought in sheets from any larger rubber shop / dealer. These sheets were used in both the inside and outside footwells of the car and the rear firewall. The rubber makes not only a good heat insulator, but also sound as well. The downside is that the rubber holds a lot of oil and water, so when removing it, don't be surprised to find rust (hopefully not too much).

If you're really keen, I guess it could be done without removing the engine, but you would have to perform the bottom half from under the car (e.g. sides of footwells, lower rear firewall, etc). It may take longer, but one advantage is that you can check the clearances as you go (I tried using the 13mm thick rubber in most places, but went down to the 10mm rubber when clearances got too tight - with the motor out, you don't get the luxury of checking this). But, it is easier to do with the engine out, and this is what I would recommend.

To remove the old rubber, try to cut away as much as you can so that you have a pattern (if possible), then the best way to remove it all is to scrape and sand the remaining bits (remember that you'll probably have to patch some rust and seal with a water base bitumen before regluing any rubber). Cut patterns with newspaper, then cut and install the new rubber.

Another suggestion is to make sure that you seal all holes, especially around the heater box and on top of the heater box near the fresh air intake (minimises the amount of engine heat that may creep its way into the cabin).

Don't forget to do this inside the cabin in the footwells too (in fact, maybe start with this easier job - you may be happy with just this improvement). Especially the footwell ducts - make up some cones of rubber to fit inside, and this area gets so hot due to its proximity to the back of the motor. Even the exhaust at the floor of the cabin lets in quite a bit of heat, so this may be a good place to start.

Good luck,

Dino
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by Interceptor3 » Fri Feb 03, 2012 9:54 pm

Thanks Dino,

Most of it has been pulled out and tossed away already, leaving a thin layer of foam still attached. Have not spotted any rust yet, really hoping there is none. So the only option really is another rubber/foam based product? Was hoping there might be an alternative that is less likely to hold moisture. Don't want to remove the motor unless I have to. If I do, it will result in a rebuild of the motor at least, an engine conversion at most ;)

Will have a look at it again over the weekend. Cheers.
Nigel Honey
Hobart, Tasmania
'72 Jensen Interceptor Mk3 128/4633
'08 Mitsubishi Lancer Evolution X MR
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by dinofritz » Sat Feb 04, 2012 12:12 pm

Hi Nigel,

I forgot to mention that in some areas (e,g, trans tunnel), I copied what Jensen did and added a foil backed fibreglass on top of the insulation to better reflect the heat, and being foil this seems to resist oil and water fairly well. On reflection, I wish that I had used this a little more extensively (especially on top of the footwells where the water tends to sit, pool and not run off) - I have seen some restored cars where the entire firewall is finally covered in the stuff (though I think this is a little too extreme).

In Adelaide, this stuff did prove difficult to find when I was doing my car, and the place where I brought it from (Bells Insulation) I think has since closed down. However, a little bit of googling has found the following link which may be of help:

http://www.advancedthermalsupplies.com. ... s/thermal/

Hope this helps - good luck,

Dino
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by Interceptor3 » Sat Feb 04, 2012 1:10 pm

This sounds similar to what was fitted... Will get some photos soon to show.
Nigel Honey
Hobart, Tasmania
'72 Jensen Interceptor Mk3 128/4633
'08 Mitsubishi Lancer Evolution X MR
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Interceptor3
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Posts: 499
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by Julian » Tue Feb 07, 2012 7:58 am

K&D sell the stuff you need. Should be able to source in Aust.
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by Interceptor3 » Tue Feb 07, 2012 9:08 am

Great, I need to order some stuff off them soon too!
Nigel Honey
Hobart, Tasmania
'72 Jensen Interceptor Mk3 128/4633
'08 Mitsubishi Lancer Evolution X MR
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Interceptor3
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Posts: 499
Joined: Thu Feb 03, 2011 7:46 am
Location: Hobart


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