Some Q's about insulating Defender firewall

[Defendozer]

I've just bought some Dynamat to insulate the firewall in my 300Tdi and have a few questions about it.

#1: I haven't pulled the dash out yet but there are some rust spots visible, mainly in the footwells. Just wondering if anyone has any recommendations for what rust killer/preventer to use? Any advice?

#2: Having never used Dynamat before how effective is it? Would two layers be better then just the one? Two layers would be 3.4mm thick, would that cause problems when refitting the dash etc?

#3: I've never removed a Defender dash before so is there any little things that I should watch out for? It is a Land Rover after all

Any advice very welcome from those in the know.

Thanks in advance, Remo

[manic]

#2
Dynamat works well as a sound deadener to stop vibration noise in panels and also reflects heat. Its not much of a sound barrier on its own.

I don't think having two layers of dynamat on top of each other would be worth the extra cost, if you went for two layers you would need to add something like dynapad as the second layer... if you did go with two layers of dynamat it would be better with one layer on engine bay side.

[DiscoMick]

For the rust in the footwells of the 300Tdi Disco I:

1. Painted it with White Knight rust converter from Bunnings.
2. Painted it with White Knight black paint containing rust inhibitor (also from Bunnings)
3. Slapped on a coat of used oil and let it dry.

Sure similar brand paints from other companies would do a similar job.
You might want to have a good luck and ensure there are no water leaks or rust holes in the floor.
Hope that helps.

[Defendozer]

#2
Dynamat works well as a sound deadener to stop vibration noise in panels and also reflects heat. Its not much of a sound barrier on its own.

I don't think having two layers of dynamat on top of each other would be worth the extra cost, if you went for two layers you would need to add something like dynapad as the second layer... if you did go with two layers of dynamat it would be better with one layer on engine bay side.

Ok sure that makes sense. According to the Dynamat website for best results use "Dynaliner" over the Dynamat, easier to fit to the firewall as well because its self adhesive.
Don't have the money for that stuff as well at the moment unfortunately so I think will just put the one layer on the inside and put a suitable layer of something on the engine bay side sometime down the track when I can afford it

For the rust in the footwells of the 300Tdi Disco I:

1. Painted it with White Knight rust converter from Bunnings.
2. Painted it with White Knight black paint containing rust inhibitor (also from Bunnings)
3. Slapped on a coat of used oil and let it dry.

Sure similar brand paints from other companies would do a similar job.
You might want to have a good luck and ensure there are no water leaks or rust holes in the floor.
Hope that helps.

Yes most helpful thank you I'll be in town tomorrow so will go to the paint shop and see what they've got.
There are no holes in the footwells....yet! I know of a few spots where water has been leaking in and dribbling down so will look into fixing them while I'm on the job.

[flagg]

My firewall is "Dynamatted" with a single layer. Make sure there are NO HOLES at all before you fit it. You will have fit problems with anything that is fixed on by two different planes at a angle.. like the accelerator - it is bolted in by two plates that are at a 45 degree angle. The extra thickness of the mat means that only one set of holes will ever line up. Its an easy fix - just cut the dynamat under one of the plates. My description isn't very good, but you will work it out pretty fast.

It will make a big difference to heat, but not to noise unless you do a lot more work and fill all the gaps. I did a LOT of this doing a full firewall swap, but how have a lot of noise coming through the heater.. so I'm going to fix that up next. Its like playing whack-a-mole, but each time it gets quieter.

[Defendozer]

Thanks flagg,

Yes I can get what your saying about the angled brackets, was able to look at that as Ive pulled all the matting out of the car and am currently treating the rust in the footwells, passengers side isn't very bad but the drivers side needs a little more TLC

It did used to have aircon so there are the holes in the passengers footwell that need to be patched up and maybe one or two others.

Once that's all done I'll be giving the firewall a coat of Killrust enamel rust prevention paint to keep it all a little more healthy.

Just another question.... How much do you overlap the sheets where they join? Or do you not overlap them?

[flagg]

Didnt overlap them at all, butted them up so there was no gap. I applied it with a few inches of cut pipe by rolling out any trapped air and ensuring it was all properly in contact too.