# Knocking noise from Bonnet area!



## jandk

Hi,
We purchased our Arto 64L a few months ago, and the first time we drove at over 65 mph, there was a considerable repeated knocking noise from the front area,
very disconcerting at first, but handling, brakes, drive all seemed ok, dropping to under 60mph the knocking noise stopped, we now think the noise is caused by the bonnet vibrating and the bonnet catch either hitting against the lock assembly, or the bonnet release arm ( the bit you move sideways to release the safety catch) touching the flexing bonnet.
Just returned from a trip to France, where it was unpleasant to drive on the motorways at around 65mph due to the knocking noise, we tried various pieces of foam, stuffed between the bonnet lower edge and the body, but nothing has yet cured the problem.
We have spoken to Travelworld, and are visiting them in early January to have a few things sorted, I also mentioned this problem to them and they are going to try and resolve it.
In the meantime has anybody on the forum heard of this "bonnet" problem, maybe it's not even the bonnet!
maybe there's a home remedy?
other than that, its superb, and really quiet
p,s, please resist telling us to drive slower !
Thanks
John and Katie.


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## erneboy

That would be hard to diagnose without hearing it, but a good mechanic should have no difficulty finding and fixing it. Could there be something loose under the bonnet blowing about at speed. I had a loose wire (leading to the wiper motor) tap, tap, tapping at speed when my van was new, very annoying, Alan.


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## jandk

Thanks for the idea re the possibility of a wire or something moving, 
I should have mentioned, the noise can be reproduced by pushing at the bonnet lower edge, a person sitting in the cab hears the same "knock",
when moving this "knocking" is loud !!
maybe we should turn up the radio !!


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## 91502

If you can replicate the noise by pushing the bonnet it sound as though the catch needs adjusting. Usually MH bonnets are large and flexible due to being made of fibreglass so take a lot of battering with the wind. I am sure they will fix it in January but make sure it is secure now as you wouldn't want the cost of replacing it if it comes off when travelling, not to mention the damage it could do to your MH or other road users. 
James


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## kazzzy

I have a 69GL and have had this problem for the past 3 years, I have had dealers look at it (well Brownhills) and have tried to resolve it myself, it does appear to be the bonnet to me it seems like the bonnet is not secure fully on the right hand side, if you look at the design the bonnet catch is fitted to the left of the engine bay. I have tried as you have various pieces of foam and have placed felt tape around the entire edge of the bonnet but it still persists although it has been somewhat improved by the modifications made.
For those of you who dont know the vehicle is an A class and the bonnet is fiberglass so does tend to flex and with the offset bonnet catch the re is little support on the one side.
If you do get it fixed please let me know what they do as it drives me insane and if I do eventually fix it I will let you know. Have any other N&B owners suffered with this?


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## jandk

Hi Kazzzy,
Thats exactly the noise and scenario, I was trying to explain. We also are trying foam pads between the bonnet and bonnet aperture, 
The noise seems to come either from the metal latch knocking against the catch, or the safety catch hitting the back of the bonnet as and when the bonnet vibrates.
As you mentioned, the bonnet does flex, a lot, and maybe some "formers" could be made up, and fibreglassed to the inside of the bonnet (horizontally) to add stiffness to remove flex and resultant noise?
I have spoken to Travelworld, and Annabel has heard of the problem, I also think it is quite likely the factory have noted this problem, and maybe they have a modification available, might be worth a call to them.
Thanks for your reply
John and Katie.


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## kazzzy

Hi John and Kate,
I speak German so I have just sent the aftersales manager at N&B Polch an Email I will see what he comes back with, I dealt with him earlier in the year as I had a cracked shower tray (thats another story) anyway he was quite helpful so I will see what he says and let you know.


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## jandk

Hi
Thank you for contacting the factory, looking forward to hearing back from you
John and Katie


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## jandk

Hi
Think I may have solved the problem, looked at the lock system this morning, and pushing the bonnet in and out to replicate the knock, also looking at the diameter of the metal latch (catch?) that is bonded to the bonnet, I believe it is too thin and moves fore and aft in the lock mechanism when in lock position causing a "knocking" sound.
Wrapped two turns of Duct or Duck tape around the latch to increase diameter, closed bonnet, no knocking when bonnet moved in and out, yet to road test, but think its the cure !
if it works I will split a plastic tube and wrap around the latch to increase its diameter.
ps it might be an idea to look for a wear mark on the latch so the tube can be positioned over the correct area.
John and Katie.


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## aikidomo

Wot next? 
Bonnet Gate!, do not mean to be flippent, just could not resist it. :roll:


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## erneboy

If turbos went faulty routinely we could have Gategate (waste gate), I could not resist either.

As far as rattles and bangs go, I always have some sponges (car wash type) with me I can tape them to, or wedge them in, all kinds of rattly things, Alan.


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## jandk

Think I spoke too soon, while roadtesting the "fix" the "knocking" sound from bonnet area is still there,
Back to the drawing board !
any suggestions
John and Katie


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## kazzzy

I am still working on it  I have spoken to my contact at the factory, he asked me for some more detail which I have sent him so hopefully I will hear from him at some point this week.


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## kazzzy

JandK Please PM me your email address, I have some info from N&B regarding a solution apparently it is not the bonnet but the grille section.


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## jandk

Hi Kazzzy
I've sent you a pm, I'd like to thank you on this forum for taking the trouble to contact the factory, I think there are a few owners that will be pleased to hear of a "fix" for this problem.
John and Katie


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## nicholsong

Interesting thread

It is also good to find Arto members posting-not been many since I acquired mine and I was starting to feel a bit lonely on MHF. I am optimistically hoping the lack of posts means Artos have few problems!

I have not had my recently acquired Arto 69GL (2003) over 65mph yet (Too Mean!) but in case I ever do will somebody please post the fix, if found, rather than only PM 

Thanks 

Geoff


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## jandk

Hi Geoff,
I received a pdf file from Kazzzy this morning, this was initially sent from N+B to Kazzzy,
The knocking noise which I and a few other owners thought was caused by the bonnet vibrating, is caused not by the bonnet, but the middle blade of the three blade grille (below the bonnet) flexing downwards at speeds around 65-70mph and banging against the blade beneath,
I looked at the grille this morning and can see a horizontal mark where the blade has been hitting.
The fix is to construct and resin a metal tab to the underside of the middle blade, also construct and fit a small vertical tab attached behind the grille to bolt the first tab to, thus eliminating the blades ability to flex,
could always just stuff some foam between the two blades!!!
I thinkthis grille design is from about 2007, so luckily you shouldn't have a problem, so speed away!! 
if anyone is interested, pm either myself or Kazzzy, and the info could be emailed to you.
John and Katie


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## nicholsong

John and Katie

Thanks for info on the problem and the fix.

I shall lash out on a bit of extra diesel to push her up to 65+mph just to find out if you are right about it being a recent model problem. Will advise.

Geoff


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