Td5 D2 engine - Acoustic Cover soundproofing

Last year I repaired the leaking sunroofs and converted their operation from 'manual' to 'electric'.

During the process, I was driving around without the headlining or loadspace trims. The increase in road and engine noise was noticeable but not intolerable.

At some point however, I turned into a real noise hunter and started filling every available body cavity with foam padding before replacing a piece of the trim. I did this in typical 'one piece at a time' fashion and was happily surprised at the ongoing benefits.

That process has continued to this day. Recent work has focused on the footwell side of the bulkhead and chasing down plasticky rattles and squeaks from the fascia. Indeed it's getting to the point of diminishing return where much more effort is needed for much smaller results!!

Recently I was reading up about the factory fitted sound proofing 'blankets' and covers fitted to the engine and transmission tunnel. When checking the big fella over it seems that one of these covers is missing!!.. 

The above diagram is from Rave and details the Td5 rocker cover components. Part No8 is the familiar 'acoustic cover ' for the top of the engine, but my interest was drawn to the item numbered '13'. This piece is attached by two bolts to the vertical rear face of the cylinder head and bridges the gap between the top acoustic cover and the transmission tunnel blanket (not shown above), both of which are present on Hx.

In the past, I have explored this area behind the cylinder head trying to find the source of a little oil leak. (the half-moon segment of the rocker gasket). 

Access to that area is very restricted and I had to use the inspection mirror to get eyes on the situation and work blind with the fingers. That is how I know the cover is not there. I recall wondering why the cylinder head had those two locating holes there anyway.

Here is a photo from the Web of the missing piece of soundproofing..

  

This photo shows the face of the blanket that is in contact with the cylinder head. As such it reveals some interesting facts.. First of all in its construction. The thick yellow closed cell foam layer (covered in oil stains) is bonded to a thick rubber base with what looks like 5 attachment points. The two central holes with rubber grommets are the ones I know about and I'm assuming the three holes near the base are to accommodate the bell housing blanket.

Looking at those oil stains, it becomes possible to work out where they originate from. - High up on the back of the cylinder head right where the rocker gasket is!  Its even possible to see the impression left by the 'half-moon' segment from the gasket.

The other impression visible just above the two bolts is the circular shape of the rear camshaft seal which, like its counterpart on the front of the cylinder head, is a known oil leak source.

This photo is also off the Web and shows the piece in question mounted to the rear of the cylinder head. One of the mounting bolts can be seen while lower down one of the cutouts fits close to the heater hose.The black pipe to the left is the gearbox or front axle breather.

The above photo is of a Td5 mounted in a Defender. There just is not any room on a Discovery to get this view due to the proximity of the engine bay bulkhead.

Another two photos from the Web. (I believe the original post was about checking the oil level, hence the dipstick lying across the first photo). These photos are of a Discovery and luckily the clean yellow foam of the blanket is just visible at the rear of the engine.

So, the next question is where can I get me a hold of one of these babies?!

Initially I curse the fact that I don't have access to the warehouse of engine delights anymore. It would prove futile and useless to go to the dealers so the only option is breakers yards and that well known Internet site.

I did think about using a foam block stuffed into that space but the risk from heat, oil and vibration that close to the engine makes me realise that the designed option is the way forward.

I am determined to source this piece because with all the soundproofing done in the cabin interior, the only real noticeable or directional rumbling now comes from the central dashboard area which is right behind the bulkhead where this 'gap' is.

To illustrate how crazy things are getting, I thought the rumbling from the central dashboard area was 'resonance' coming through the heater vents on the central dashboard. I tried opening and closing the vents and altering the settings to try and alter the note without any difference being made!!

While installing the wiring in the footwell for the door lights, I took the opportunity to install more soundproofing foam behind the fascia and high up above the existing soundproofing onto the bulkhead.

It was this instillation that then drew my attention to the upper central dashboard area and the missing engine blanket.

I used foam blocks cut roughly to shape and held in place by compression. I was very careful not to foul any wiring, cabling, moving flaps.....or....

 ..steering columns and brake pedals!!

This photo shows the grey foam that I fitted to the bare bulkhead above the pedal box on the drivers footwell. That 'sink plunger' looking thing is the steering column. The black area is the limit of the factory fitted carpet and soundproofing. I have to report that this addition really made a difference to the interior cabin sound when driving.