Hi -
Been asked for this a few times, so will post it here (originally posted at TRVN).
It was an easy project to do, though it does take a bit of time as there's a lot of waiting for silicone to dry between steps.
Noise reduction in our unit was significant - at least 40%.
If I had to do it again, I would skip the hi-heat tape for joints, and use thin sheet aluminum (or SS - like the stuff used to patch mufflers) with silicone as an adhesive to finish corners etc. Slower - but a better way to do it. I've had a few pieces of tape come off, as they do get hot, and then are blasted by the fan when it comes on.
Cheers -
Rob
REPOST:
FRED Engine compartment/cover project
Supplies
Insulation pins - I used pins with a 2"x2" square perforated back as I was mounting to the insulation already in place. Pins were trimmed to length, with about ½" extra before mounting. Clips slide easily one-way onto the pins..
http://www.leevalley.com/home/temprl/trvn/Pins.JPG (74K)
Rockwool is easily cut with a utility knife, and has excellent sound deadening and heat insulating properties. It's like a fiberglass board – but deforms very easily. I used 2 two foot by four foot sheets. (I have about 50% waste)
http://www.leevalley.com/home/temprl/trvn/rwool.JPG (45K)
Heat blanket – this is about 5/16 – 3/8" thick, with a fiberglass core and a reflective aluminized exterior. I put this over the rockwool, both to reflect heat, and as a moisture barrier. All exposed edges were sealed. (shown lying on top of the access cover for scale) Comes in various sized rolls – I used about 20 sq feet.
http://www.leevalley.com/home/temprl/trvn/hblanket.JPG (43K)
Insulation adhesive – I used a high tack spray adhesive. Note that the pins and tape really provide the strength to hold everything in place – the adhesive make assembly easier, and will keep material in place while you work. I am not relying on it to hold up to high heat...
http://www.leevalley.com/home/temprl/trvn/cantop.JPG (26K)
http://www.leevalley.com/home/temprl/trvn/adhlabel.JPG (19K)
Flexible Heat tape – A fiberglass core high strength tape, both flexible and compressible. I used this for edging on the access cover, and wherever I needed adhesion without stiffness.
http://www.leevalley.com/home/temprl/trvn/tape.JPG (62K)
Sheet Heat Tape – (no picture) Similar to the above, but sold in sheets. A much stiffer fiberglass core, aluminized surface, and high strength adhesive. Like a stiff cardboard, but can be bent and will hold it's shape somewhat. I used it for inside corners, and anywhere stiffness was desirable.
High temp silicone – available in more than one temperature range, I used the black stuff (also used for making gaskets). I used two tubes (caulking gun size!)
Problems to Address
There were a number of problems with how our engine compartment was sealed. Firstly, the gasket material appeared to be hastily installed, or had slipped after installation. In places, it has been installed over carpeting. In the corners where the cover transitions from horizontal to vertical – the gasket bridged the corners – leaving significant gaps.
The front face of the doghouse (that mates with the vertical cover face) was completely uninsulated. In addition, our access cover had not been fastened at all. While driving – when the engine fan came on – it could be like having a hair dryer blowing on your leg.
http://www.leevalley.com/home/temprl/trvn/seals.JPG (52K)
Area "1" shows the gasket cutting a corner – Area "2" is inconsistently applied.
http://www.leevalley.com/home/temprl/trvn/LHSb4.JPG (46K)
http://www.leevalley.com/home/temprl/trvn/LHSb42.JPG (77K)
http://www.leevalley.com/home/temprl/trvn/rhsb4.JPG (65K)
Above are various views of the engine compartment – looking in from the outside. Couple of things I also wanted to fix were covering the exposed edges of the OSB floor boards – visible in the second and third photos. Note the bridged corner in the second photo – about a ½ gap through which air flowed freely.
Installation
First panel – I extended this panel beyond the fiberglass frame by about 1 ½". Once taped up, this made an excellent bumper for working within the engine compartment, as well as affording a much better overlap between the access cover and the doghouse.
I chose the order in which I installed the panels carefully – as I wanted each successive panel installation to "trap" the previous panel. My order was front, top, then sides. It's also important to know this order so you can plan pin locations. As this is a confined area, top and front panels were cut to size – and the cut in half to get into the compartment. I mounted the front panel pieces first, then trimmed to size once in place.
http://www.leevalley.com/home/temprl/trvn/pnl1.JPG (51K)
http://www.leevalley.com/home/temprl/trvn/pnl1t.JPG (46K)
Next step was to position the pins to hold the side panels, and the top panel (front panel is held in place by the top, sides, and taped to the doghouse). Apply a generous amount of high temp silicone , and push into place on the existing insulation. The excess will extrude through the plate holes, providing an additional mechanical lock. Take into account the order of mounting panels, and the panel thickness! My side panel pins had to allow for the space taken up by the top panel...
http://www.leevalley.com/home/temprl/trvn/pinglue.JPG (31K)
http://www.leevalley.com/home/temprl/trvn/pinmount.JPG (38K)
http://www.leevalley.com/home/temprl...lookingout.JPG (105K)
The last shot above is actually looking out of the doghouse!
Final job day one was to seal the front panel to the doghouse...have to let all the silicone dry!
http://www.leevalley.com/home/temprl/trvn/pnl1seal.JPG (47K)
Next day, I started installing the side and top panels, and also taped up the exposed edge of the front panel. The rockwool pushes easily on to the pins, and is locked in place with clip plates.
http://www.leevalley.com/home/temprl...ornerafter.JPG (74K)
http://www.leevalley.com/home/temprl/trvn/toppnlin.JPG (60K)
http://www.leevalley.com/home/temprl/trvn/frontedge.JPG (49K)
Once the rockwool panels were clipped in place, I cut heat blanket sections , sprayed adhesive onto the rockwool, and clipped the blanket in place as well. Corners and edges were sealed with the stiff sheet heat tape, taking care to leave no edges exposed that would be caught in an airstream.
The finished LHS can be seen below...(hard to photograph the reflective stuff – but it looks great!)
http://www.leevalley.com/home/temprl/trvn/lhsdone.JPG (120K)
http://www.leevalley.com/home/temprl/trvn/lhsdone2.JPG (55K)
Access panel
The access panel has a raised center, with a recess around the edge – presumably to accept the rubber gasket applied. On our unit – the gasket had been pressed flat on the horzontal surfaces. The carpet applied to the access cover ran completely into the recess on the underside.... So the "seal" was a carpet-to-flat gasket seal...
Job one there was to trim back the carpet to the perimeter of the recess, taking care to ensure it was still securely adhered to the cover. I also used shears to trim the excess pile from the underside of the cover, while leaving the carpet backing.
http://www.leevalley.com/home/temprl/trvn/dh1.JPG (40K)
http://www.leevalley.com/home/temprl/trvn/DH2.JPG (53K)
Second shot above shows the recess cleaned out...
Next step was to fill in the recess with silicone... this was done in two stages – and a level suface obtained. It was quite irregular on the first pass!
http://www.leevalley.com/home/temprl/trvn/DH3.JPG (29K)
http://www.leevalley.com/home/temprl/trvn/dh4.JPG (34K)
I then made an edged heat blanket ¼" narrower than the size of the access cover – using the flexible/compressible heat tape on the edges. This was then sercurely glued to the existing heat blanket. Note that the outer inch or so remains unglued, and floats over the silicone filled recess.
http://www.leevalley.com/home/temprl/trvn/dhcorner.JPG (72K)
http://www.leevalley.com/home/temprl...ndercorner.JPG (61K)
http://www.leevalley.com/home/temprl...hcoverdone.JPG (65K)
On top of the flattened gasket, I put a ¼" bead of silicone down the center. Now when I put on the access cover, there is an airtight seal formed as the floating edges of the cover heat blanket are sandwiched between the silicone bead on the gasket, and the silicone seal in what used to be the recess.
So there you have it – it looks great, and work well.
Cheers –
Rob
_________________
Rob Lee
2007 Allegro 32BA FRED
2001 Corolla
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