Toyota Corolla Sound Insulation

[pmf]

I have aToyota Corolla TS TREK 1.8 MY21. I was looking under bonnet for first time and noticed no sound insulation on under side bonnet/hood. It looked unfinished. A friend has a CHR 2.0l GR Sport MY 21 and it has under bonnet insulation.  Given that if I recall the Corolla windscreen has front acoustic glass I thought they would have sound insulation also under the bonnet if there was a need at the windscreen. The windscreen obviously does a great job as the car is pretty quiet from inside but to me it does look unfinished under the bonnet.

Do any of the Corolla models have sound dampening there perhaps the 2.0l.

[Catlover]

Perhaps the acoustic windscrreen negates the need for under bonnet sound proofing.  Why go to extra expense and add weight to the car just to make it look "finished"  (whose going to notice)

[Gerg]

I think this question has come up before a few times.

Whilst you wait for an answer from someone who works at a dealership or similar - I think the fitting of this insulation is trim-level dependent (unlike the Auris before it). 

The 2 litre engine, unlike the 1.8,  has direct fuel injection, which I would expect to be noisier than the other fuel system - port injection.  The pump and injectors are working at much, much higher pressure, so extra noise is to be expected.  But the 2 litre has port injection too, for when the engine decides that that system is more effective. 

I have read somewhere (on another forum perhaps?) that the insulation that you are missing is surprisingly expensive to buy as a spare part, unfortunately.  The part isn't very heavy at all.

I have run other cars with this type of trim removed to see what difference it makes, it was less than I was expecting, but this is so objective, obviously!

On our Auris, I have removed this trim in order to fit some DIY cut-to-size pieces of Dynamat brand sound deadener, before refitting the insulation that you mention.  That gives a noticeable improvement.  Not very large, but certainly worthwhile.  It slightly quietens the road noise as well on the Auris.  Dynamat has a foil backing, so it is visibly obvious it is fitted when the bonnet is up, but not when underneath something else!  It is also very heat resistant indeed.

Worth thinking about if you expect to keep the car a long time. Dynamat is quite expensive, but not for the amount needed for underneath a bonnet. Less than £30, I think. 

[Gray86]

It’s probably not there as it isn’t needed. The engine is very quiet from outside the vehicle as it is. It’s louder inside than outside. Extra soundproofing around the firewall would be preferable. 

[pmf]

Thanks Gerg, the Auris TS the Trek replaced is still in the family and certainly keeping the Trek for quite a while so definately looking into this.

Joe, thanks  and your right a small saving on each car mounts up but unfortunately I noticed immediately, it just looks wrong, you see the windscreen washer pipes and all the numerous holes etc.  I just expected a bit more given the price of these cars, a bit of covering material/ sound insulation would have just finished it. It is a minor thing admittedly and certainly not something that's not gonna change my overall opinion that it's a great car. If it is fitted to the 2.0l motors then it may be available so I may have a look at whether its affordable, but as Gerg mentioned probably too expensive to be worthwhile.

[pmf]

Graeme, yeh your probably right I think something there would have finished it. I note you have the 2.0l Touring Sport does it have the insulation on underside of bonnet? Thanks

[Gray86]

12 hours ago, pmf said:

Graeme, yeh your probably right I think something there would have finished it. I note you have the 2.0l Touring Sport does it have the insulation on underside of bonnet? Thanks

Hi, just checked and yeah it does have some 

[oldcodger]

There are places that specialise in aftermarket sound insulation fitting and kits, but the doubt they will have anything for the new Corolla.

However there are lots of materials you can fit yourself to give a good finish all over the bonnet, not just odd stick on silver pads.

A simple search shows up loads of suppliers and materials along with ytubes on fitting  them; be a lot cheaper than anything from Toyota which even if classed as a spare will probably not be on their shelves in a hurry.

Even our old Corolla has bonnet insulation and a large engine cover which also aids engine noise insulation but we added extra sound deadening pads to the doors and boot which made a noticable reduction in drumming noise from the back plus a much better sound from the Speakers.

 

 

[pmf]

Graeme, thanks for checking, I now know at least its available, whether affordable is a different question. I'll have a word with my local parts department.

Thanks re aftermarket info and I will look at various aftermarket options particularly once I find out cost of Toyota part.

Thanks for the help.

 

[TonyHSD]

10 hours ago, pmf said:

Graeme, thanks for checking, I now know at least its available, whether affordable is a different question. I'll have a word with my local parts department.

Thanks re aftermarket info and I will look at various aftermarket options particularly once I find out cost of Toyota part.

Thanks for the help.

 

Hi, if you ask the part department they may say that this part is not available for your car since it’s 1.8, just tell them to look for 2.0. Just in case the parts advisor is thick and does not want to help. 👍

[Roy124]

I await more info with interest.  Whilst noise levels might seem a subjective issue, they are also a personal one.  I have severe high tone frequency loss; unwanted noise at other frequencies does not help.

Regarding 'nothing for your 1.8', I had one ofe the first batch SAAB 99 with the Triumph 1854cc engine.  I was told to go to a Triumph garage for any spares but not to tell them it was for a SAAB 🙂

[Roy124]

After the discussion on sound proofing I decided to do a check on today's run. Cruising at 65 I was on a down gradient and only running on Battery.  As the gradient changed the engine kicked in but I noticed no change from the previous tyre noise.  Tyre noise is significantly more than any engine noise.

I had been considering soundproofing but have now ruled that out.

[pmf]

I've asked my local parts department to check price and just waiting on them getting back to me. For me I think it looks unfinished but hope it may help when on a long climb when the engine has to work a bit harder, but in most driving situations without much load or higher revs I think your right the noise from engine in the cabin is pretty quiet but likewise I do notice tyre noise. However until I get the price, I'm not committing to it yet.

[oldcodger]

Sound proofing is limited to some degree  by the selling price point, so expect there would be some improvement from bonnet insulation.

You can remove the front wheel arch liners and attach sound deadening pads etc  to the inside of the wing and door pillar to help reduce type noise, if its such a concern, same with the rear wheels where you can often get access to the relevant panels from inside the boot.

We used the Dynamat type pads to good effect.

 

[Roy124]

Oldcodger, if your car detail is correct then what you advise is sound 🙂 but DIY insulation for new cars is perhaps not the best option.

[Parts-King]

On 4/18/2021 at 5:02 PM, pmf said:

 

Do any of the Corolla models have sound dampening there perhaps the 2.0l.

The 1.8 and 2.0 share the same bonnet, so I suppose there is no reason why you could not fit the sound deadener from the 2.0, however, do you want to spend £186 on it? 

 

[Roy124]

PK, that's a NO from me. 

[TonyHSD]

But that sound proof on the bonnet only reduces the noise from the engine outside the cabin and will not add much if at all extra sound proof to inside the cabin, perhaps they just not bother to install one for financial reasons, although Prius has them and older Aurises. I agreed, it looks unfinished and ugly but who is watching that and how often?! Ok, I open the bonnet once or twice a week but believe me I am interested to check fluids levels and oil more than how the bonnet or engine look, it’s all covered in salt and grit anyway, the car doesn’t stays clean and shiny for long . M25 around London the gritting is live every night and will continue at least to the end of April. 🤭😶

[Roy124]

Tony, you are arguing that they don't need to fit any bonnet insulation.  In support of that, they add a noise generator to give an audible warning at low speed and above that external engine sounds are a bonus!  The sound levels emitted from 1.8 or 2.0 engines cannot be that different.

Given my limited observations engine noise at any speed is imperceptible against tyre and wind noise.

Do all 2.0 have the insulation or only higher spec?  It might be more a selling point than a necessity.

[TonyHSD]

48 minutes ago, Roy124 said:

Tony, you are arguing that they don't need to fit any bonnet insulation.  In support of that, they add a noise generator to give an audible warning at low speed and above that external engine sounds are a bonus!  The sound levels emitted from 1.8 or 2.0 engines cannot be that different.

Given my limited observations engine noise at any speed is imperceptible against tyre and wind noise.

Do all 2.0 have the insulation or only higher spec?  It might be more a selling point than a necessity.

Hi, I am not sure about if all 2.0 has insulation on the bonnet, perhaps they do. The 2.0 has direct injection fuel system that works under high pressure and does make more noise than 1.8. Interestingly Prius gen 4 same as Corolla 2019 both 1.8 hybrids and Corolla doesn’t have insulation., selling point maybe, everything is possible. Here is the video regarding these. At 4:35, not only that but and engine cover is missing, Corolla seems like more accessible  (cheaper) product, although they are similarly priced. 

 

[Devon Aygo]

6 hours ago, Roy124 said:

Tony, you are arguing that they don't need to fit any bonnet insulation.  In support of that, they add a noise generator to give an audible warning at low speed and above that external engine sounds are a bonus!  The sound levels emitted from 1.8 or 2.0 engines cannot be that different.

Given my limited observations engine noise at any speed is imperceptible against tyre and wind noise.

Do all 2.0 have the insulation or only higher spec?  It might be more a selling point than a necessity.

 

Other than being transverse 4 cylinder engines the 1.8 2ZRFXE and 2.0 M20AFXS share no common architecture.

According to an engineer I managed to corner, the direct injection on the 2.0 was found to be intrusive so all 2.0 gain additional cabin & engine bay insulation 2.0 also have an insulated windscreens over 1.8  

[Roy124]

Thank you.  I wonder how the sales between 1.8/2.0 split.  I wonder just how much real difference there is between the two engines in terms of performance and economy?  Is the profit margin on the more macho number sufficient to make it really profitable?

 

I found this link:

Corolla Hybrid: 1.8 vs 2.0? - Corolla Club - Toyota Owners Club - Toyota Forum

I agree with AndrueC, the 1.8 meets my requirements and I have only one 'slow' gripe.  If I use the adaptive cruise control, 'tuck in' behind the HGV convoy with 65 speed set, on a busy road it is quite comfortable.  With and maximum spacing set but lane 1 travelling at lower than 60, HGV joining the 'convoy' are tempted to overtake to use my safe space.  

Where lane 2 is travelling at 70, or empty, the power is available to 'get out of Dodge'.  The first time I experienced this was in the demonstrator and I was doing 70 plus with no sensation of a power surge.

[Parts-King]

5 minutes ago, Roy124 said:

Thank you.  I wonder how the sales between 1.8/2.0 split.  I wonder just how much real difference there is between the two engines in terms of performance and economy?  Is the profit margin on the more macho number sufficient to make it really profitable?

Can't tell you how profitable they are, but I have had both engine models, the 2.0 is vastly different in the feel of it's performance, but the MPG was averaging about 56 for me, and 70 ish in a 1.8 version 

[Roy124]

PK, happy with that :).  My 1.8 would get about 57 during the winter months and is now coming up to 65ish.  I have one managed a couple of 50 mile journeys with about 25 miles dual carriageway so have yet to experience consumption over a longer journey.   I certain enjoy putting £20 of petrol in rather than £80 of diesel.

I did some comparison between running an old diesel Merc for a year with high fuel and maintenance against a new Toyota with high repayment and low maintenance and it was practically cost neutral.  This also factored in insurance, tax, tyres etc.

[Parts-King]

The first 1.8 Corolla I had (I have had many) averaged 74 MPG over the summer, amazing MPG for a comfortable automatic car