Soundproofing 93 Defender?

Have attempted to make my Isuzu Landy quieter, and have managed to make it more bearable.
Used Dynamat extreme on the inside of the bulkhead, over the front seat boxes, and over the rear wheel arch boxes. Then covered all of this with carpet.
Stuck 10mm thick 'Formshield' (self adhesive closed cell foam with silver lining) over engine side of bulkhead. Also removed the headling on the roof and stuck this over the entire inside of the roof.
Under the floor carpet mats added additional closed cell foam (like the stuff camping mats is made of).
Under the bonnet, have formshield type foam stuck to the panel, and added a genuine underbonnet sound deadener on top of this.
Fair bit of work, and not sure what it all ended up costing, but can now even hear people sitting in the rear cargo area now. I could barely have a conversation with the passenger in the front seat before this.
Still have to raise your voice a bit though, and it is still noisy compared to most other vehicles.
Bonus is the heat reduction in the cab.

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Originally Posted by AdsLandies

Under the floor carpet mats added additional closed cell foam (like the stuff camping mats is made of).

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This is the EVA foam I was talking about earlier. I keep forgetting most people know it as camping mat foam.:angel:

Best results come from it laid loose so you can use the air gap behind and between for some extra insulation. It's great stuff and quite cheap too.

Has anyone gone to the trouble of measuring the ambient temp under normal driving conditions under the bonnet. Most of the EVA foil backed products are rated to about 100 dec C. I would imagine the temp immediately above the turbo would be well above that. No point installing it if it disintegrates from the heat.

I have a engine management temp monitor with the external sensor. I might position it under the bonnet above the turbo as an experiment.

The other issue that just occurred to me about installing heat/sound shielding under the bonnet is the fact that the alloy bonnet would conduct heat efficiently thus dissipating the under bonnet heat. Add shielding to the bonnet, to my mind, would trap the heat. Or does the air flow under the bonnet make the problem negligible? Therefore benefits outweigh the negatives.

cheers MLD

I would keep EVA foams inside. Any turbo/exhaust heat is going to be well over 100C. I also like to keep foams away from the engine bay as they become stamp-pads if oil gets on them.

Underbonnet my approach has been to simply stop rattles. On my work-car (not a defender) I used expanding foam between the bonnet frame and skin as a deadener. It worked.

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Originally Posted by MLD

....The other issue that just occurred to me about installing heat/sound shielding under the bonnet is the fact that the alloy bonnet would conduct heat efficiently thus dissipating the under bonnet heat. Add shielding to the bonnet, to my mind, would trap the heat. Or does the air flow under the bonnet make the problem negligible? Therefore benefits outweigh the negatives.

cheers MLD

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The under bonnet insulation will work well to reduce noise. While some heat will be retained, I think the fact that the fan maintains an airflow over the engine even at low speeds, should be enough to see heat / air dissipated under the car. I had 10mm dense closed cell foam on the SIII, with no overheating issues, and I'm sure the Defender runs cooler.

Having said that, vented bonnets are good for reducing engine bay heat, so I suppose it depends what your main concern is, if your'e doing heavy work in 50 degree heat, then heat dissipation may be more important that sound reduction.

On a similar heat issue, I've got a friend with a PUMA who gets a lot of heat from the exhaust that runs just under the drivers footwell. We were thinking that a scoop on the RH guard might direct air flow down over the inner guard and past the RH footwell, helping to dissipate heat. Just a RH version of the heater air scoops often put on the LH guard.

Hi michael 2

Re your puma heat issue I tried a number of options to redirect flow and install heat shields with out much success. Recently I removed the cat and results so far are dramatic. Whilst it is winter a recent 2 hour highway run that would normally lead to a hot footwell was fine.

My 90 Td5 is off to get steam cleaned and undersealed next week, I decided to take off the plastic guards under the engine (pain in the arse,had to drop the prop and anti-roll bar) and gearbox. Do these serve any real purpose in reducing noise levels as I'm tempted to leave them off? All they seem to do is trap dirt! Plus the foam is knacked after a fuel regulator leak:(

The Wright / Exmoor moulded matting arrived last week and the sound meter arrived a few days later.

Today was the first sunny day in Melbourne for awhile, and it coincided with a day off work for me.

It's now in the car, so I'll have some freeway speed testing in the morning on the way to work.

I've got the Dolium / Frontrunner safe under the cubby, so that was anothe big hole I had to cut, but I insulated it both inside and out with the foil backed butyl stuff from Jaycar, so hopefully that maintains the integrity of the insulation barrier.

Some trimming had to be done to accomodate the A/C unit, and the A/C kick panel needs the square bottom edges rounded off to fit in again.

I'll update tomorrow with sound data.

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Originally Posted by Michael2

The Wright / Exmoor moulded matting arrived last week and the sound meter arrived a few days later.
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I'll update tomorrow with sound data.

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Be very interested in how much of a difference the matting makes for you as I'm looking at it also.

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Originally Posted by samuelclarke

Be very interested in how much of a difference the matting makes for you as I'm looking at it also.

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Sorry about the delay in getting figures to you. On the first day the accelerator stop needed to be wound out to accomodate for the mat, so I couldn't get a good throttle going on the way to work. Peak hour and slow traffic didn't help on the way back.

So far idle noise measures the same (55db) as before, but feels quieter.

Accelerating up hill at 80kph is at 73db, down from around 76db.

100kph is around 76db down from 78db.

What I'm going to do is make up a comparison table using the TD5D2a HSE auto as a benchmark of a relatively quiet diesel.

I'll compare a standard and insulated 110SW at

IDLE
60kph
80kph Cruise
80kph Uphill Accelerator
100kph

The next phase will be to remove the bonnet insulation, fit foam against the bonnet, and refit the original on top, as most of the noise now seems to be coming from the front.

I'd also like to do under the roof lining and the doors. Hopefully I can get a mate with a standard 110SW to come over and do the comparo over the w'end.