Induction noise ????

[Den]

We have a nice MH, but under load we have what i would call an induction noise (air intake). The question being has anyone fitted or had fitted from the magazine. Blankets that cover the engine, and if so have you noticed a difference. Any recommendations gratefully received.

[Guest Tracker]

I am surprised that induction noise is that great.

 

I don't want to insult your intelligence and at the risk of being over simplistic can I ask - do you have an air filter in place and are you sure that all the bulkhead and cab floor grommets are in place as these can allow an amazingly disproportionate volume of noise through a very small hole?

 

Another source of noise intrusion can be an ill fitting cab door and if you can see daylight through any part of the door to rubber seal - often around the wheel arch - that won't help. Can often be improved by pulling the rubber seal off, bending the flange outwards and resealing.

 

I've never covered any engine with a blanket - well not since the days before anti freeze was cheap - and the thought of a lack of airflow around a hot engine does not appeal to me one little bit no matter what the assurances from the supplier.

[colin]

I you name the van someone might have a specific answer

[mirage]

When you say induction noise under load does it have a sort of irritating gurgling sound to it pulling hard uphill between 50-70MPH. We had this on an "A" Class, dealer fitted a noise killer kit which included an engine blanket but it did`nt really improve things greatly, Fiat blamed the conversion type. I don`t know how common a problem it is have seen some owners comment on it, I have heard it said re-chipping can result in improvements.

[Den]

It's a 9 series LeVoyageur A class 3ltr 6cyl merc. The sound could be described as a roaring sound . On the flat and light on the gas its OK. Demand more power then it becomes Vocal. Not the normal diesel knocking noise but a desperation to gasp air. Wife would say more a growl..(the mh not me). I need to do something and also a friend with the same mh. (his waiting for me to cure mine first, no flys on him)..

[Den]

Hi tracker

All grommets are in place and this is a common fault with this particular mh. All doors etc fit well. Hayes did fit some sound deadening material below the bulkhead on my previous mh and the present one. But i want to improve, it made perhaps a 50% reduction, but that isn't really satisfactory.When i say blanket i mean the sound deadening type purposely made for the job. Seen at shows and advertised in the MMM.

[docted]

Den

Have you made sure that all is well mechanically?. I recently had a problem with my daily runner that sounded like a blown exhaust. I took it to the garage where they discovered that the air inlet pipe from the filter box was loose causing an awful din.

[Brian Kirby]

docted - 2008-12-06 2:36 PM Den Have you made sure that all is well mechanically?. I recently had a problem with my daily runner that sounded like a blown exhaust. I took it to the garage where they discovered that the air inlet pipe from the filter box was loose causing an awful din.

Sounds highly plausible to me.  The noise seems to relate to the degree to which the throttle is opened, so seems likely to be air (i.e turbo) pressure related.  A missing/damaged seal, or loose clamp, between the turbo and the air filter, an air leak downstream from the turbo, or even some air leakage from the turbo (unlikely, I guess, but all mechanical parts are assembled, so poor assembly must remain a consideration until eliminated).  Small gaps can make a disproportionate noise when significant air pressures are involved.

[Den]

Hi

It does sound like a loose turbo pipe but all has been checked by me and professionally . The previous mh now owned by Collin (his waiting for me to rectify mine first ) Sounded the same. I have not as yet found a merc van with the 3ltr to compare. Idealy a rolling road would help, ie the f1 honda factory (not being used at the moment.).

[Basil]

We have a 'Noise Killer' insulation kit fitted, which includes the lead blanket over the engine, to our Boxer this has dramatically reduced the noise levels inside the cab particularly at speed, but it is mainly mechanical noise and road drumming that has been reduced it has had little effect on the air / turbo noise which possibly if anything is a little more noticable as the louder mechanical noise is now damped down.

The blanket has had absolutely no effect whatsoever on the running temperature as it does not actually rest on the engine but is spaced away so that air can still pass across the top and down the back.

 

Bas

 

P.S. Just a thought our Boxer is fitted with a boost guage that shows the pressure of the turbo, the supply tube to this got cut last year and that made a very loud 'induction' noise although the cut was very small and had little effect on the running of the van.

[Den]

Hi Basil

Thanks for the reply on the very product i'd looked into, but had never heard of anyone using it. When stationery because your not requirering power only revs we canot pinpoint any leaks etc. Did'nt realise the fiats were fitted with a turbo gauge. I'll ring a merc garage to see if the vans have them fitted ...Just in case... Road and engine noise are not a problem. Its all down to this air intake noise.