Drone Noise at 1500Rpm Prado 2006 3Ltr TD

[gazburn Lurker Find all posts View Profile Close gazburn]

I recently found a post regarding the Drone noise that occurs around the 1500 rpm on the TD 3ltr engine . The noise has been anoying me ever since I bought the Prado , I was told by a mechanic it was caused by the resonant frequency of the guard where the air box gets its air. I found some info of how to fix it, at least reduce the noise. I bought some Dynamat sound insulation on ebay and I have fitted it inside the guard and it has reduced the noise considerably.
Cost Dynamat $60.AU Fixing Lugs for the wheel arch cover $14.00 for 10 Lugs.

[raydhillon Junior Member Find all posts View Profile Close raydhillon]

gday gazburn thats good to hear !

was it a hard mod to do? i plan to get round to it on dads 150.

[Guest Close Guest]

This solution was discussed in the 150 section
http://www.pradopoint.com/showthread...on-and-rattles

[Rowdy Lurker Find all posts View Profile Close Rowdy]

Hi there, This is my first post.

I did this fix to my 08 KDJ120 and the resonance is totally gone. So happy as it was really bad.

Accessing the inner guard on the 120 series will be different to the 150 series. I read that post first and went the same way by attempting to remove only the wheel arch lining and accessing the inner guard from inside the wheel arch. I would advise against this on the 120 series.

Consider removing the entire front guard (front quarter panel). That is, leave the plastic flare and wheel arch lining attached to the steel guard panel. For me this was far easier, and yes I found this out after I had pulled off the flare to access the remaining black plastic clips.

It may depend on which bull bar you have fitted as to how easy it is to remove front guard panel. I have an ARB and access to the necessary fasteners wasn't too bad.

This is what worked for me:
Remove mud flap
(I also had to remover ARB Under guard on the right)
Remove 3 air box bolts
Remove only the black clips that can be accessed with pliers from the engine bay.
Remove 2 outer head light fasteners
Remove 7 fasteners holding the front quarter panel.
Might be 1 or 2 more plastic clips attaching the wheel arch lining somewhere. (If you cant access the tabs with pliers good luck with them)
Remove guard panel

This also makes it much easier to apply the sound proofing. And, very importantly it allowed me to clean out all the crud from the inside the guard (I will do this every couple of years). Everything that gets washed down from the area under the wipers ends up inside your front guard panels.

I stuck sound proofing to the inner guard around the air intake hole and to the inside of the guard panel.

[james_hbay Lurker Find all posts View Profile Close james_hbay]

maybe a snorkle?

[North Lurker Find all posts View Profile Close North]

Thanks for the instructions Rowdy,

However I need to add a couple of points:

• On a standard Prado, removing the quarter panel (QP) seems to be much more difficult than the above instructions. I guess access is easier with an AM bumper? The bolts at the front of the QP are not accessible without removing the bumper, which was something I was not prepared to do. So I used Rowdy's instructions, along with the 150 method and it worked a treat. The vibration is 100% gone (I was so nervous it wouldn’t work, but it did). A noise is still partially there, but it sounds more light a very faint exhaust drone between 1500 - 2000rpm (sports exhaust note if anything), but nothing like a vibration and I am over the moon, its such peaceful motoring now. Here I go:

• This method will take about an hour.
• You do not need to remove the wheel.

Equipment:
• 10mm socket and ratchet (preferably a small ratchet)
• 12 replacement inner guard plugs from Toyota (Call Toyota and describe what you are after and they will know) Around $2 each.
• 2 rolls of response sound deadener (the 150 guide refers to Dynamat, but I couldn’t find it locally in QLD Australia, so I got Response Sound Deadener from JayCar. It was $29 a roll ($20 on special) and I got 2 rolls and that just made it, but you might want to get 3 to be safe).
• 3 long plastic fasteners (used in electrical cabling)

Instructions:
• You need to remove the black plastic guard under the driver’s side front quarter panel wheel arch. This will give you access to the void where the air intake is located.
• Remove the mudguard – 3 bolts; 2 inside the guard, 1 underneath near the footstep.
• Undo the 6 bols that line the flare wheel arch.
• There are 2 more screws under the front bumper that hold the guard that need to be removed.
• Inside the guard you will see a number of plugs holding the inner part of the guard up, these need to be removed. In step 3, where the bolts were removed, these are also plugs so they need to be removed too.
• With a set of cutter pliers, wriggle the flat end against the plastic and move from side to side and pull to remove the plugs.
• They may come out, but if they don’t, cut them off with the pliers. I saved 3 from 12, but you might have more or less luck. If you cut them, just push the other side of the clip though the hole and you will hear them fall out.
• Wiggle and push the guard in the direction of the motor and it will come off. If it doesn’t come off, there is still a plug somewhere.
• You should now be able to look up and see the intake baffle.
• At this point I took the car for a drive and I couldn’t hear the noise, which supports the idea of the noise resonating in the confined space.
• Get a dry rag and thoroughly wipe down the inside of the guard, then follow it up with a wet sponge and wipe the inside clean. Don’t use a hose as there are electrics up there.
• Wiggle the intake baffle, if its loose use the fasteners and tie it down to the mount that is holding it (I didn’t want this to be the problem and have to start again).
• You now need to line the inside of the QP and engine bay panels with sound deadener. You can’t simply just throw the whole roll up there, you need to cut strips and shapes off to stick to each section of metal. The process I used was pretty rough, simply put my hand up there and guess-timated the shape and size I needed and cut it off and stuck it on there.
• Make sure you put as much up there as you can, because you don’t want to come back for another visit. I had literally every part covered in the stuff. Except a little section to the front of the car, which I couldn’t cover as I only had 2 rolls.
• At this point I took the car for a quick drive to make sure I couldn’t hear anything with the plastic panel OFF. No sound, yeeow!
• Sit the black inner guard liner back into place.
• Start by putting the wheel arch plugs in first as you can’t go back to these. Make sure the black plastic us tucked under the wheel arch the whole way around.
• Move to the inside plugs, not forgetting the ones near the mud flap.
• Put 6 guard bolts back in.
• Put 2 bolts under front bumper back in.
• Put mud guard back on.
• Take for a test drive, hopefully you won’t hear any noise and give yourself a pat on the back and crack a beer.
• Marvel at your mechanical skills.