Foil heat shield over rear exhaust box

B

Billy Smalls

Member
Hi - The foil heat shield that sits above the rear exhaust box has completely detached itself at the trailing end and is making an annoying clatter over every bump.

The fixings have long since 'returned to earth' so there's nothing to attach it to - I'm thinking of drilling a few holes and blind riveting it to the plastic undershield but has anyone else thought of anything better?

Cheers
 
What I have done in the past is to sand down the old stub so the surface is flattish. Then Grind down the head of one of the self tapper undertray fixings. Then araldite the bolt to the the old stub base. Reinforce with plastic padding. You can then use the top hat nuts to attach the heat shield. A bit if a faff but it what else are we doing on lock down! Picture of unmodded bolt and top hat nut
image.jpg
 
Thanks - that is a bit of faff but I might give it a go - and we're sure the heatshield is needed? is it protecting plastic from a hot exhaust?
 
I made my own poor-man’s stud plates with some bolts and a large washer. Mixed up some JB Weld epoxy and put some aluminium foil tape over the bolt to hold the epoxy in place around the fixing point and try to keep the mess down a bit. Still going strong.


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There's been a few threads on this over the years - rivnuts were seen as the preferred solution it seems.

Personally, I've been thinking of different methods and the one I'll be trying in the near future (when the weather improves) is to grind down the remaining stud, drill out each spot, de-burr, paint/corrosion treat and then use rubber well-nuts with A4 stainless hardware. This will have the benefit of a little physical isolation between the body and the shield, lessening noise transmission and it's also cheaper than getting rivnuts and a setting tool.
 
I liked that idea and have some of the rubber-type fixings you mention but the struggle of being under a car on jack stands trying to drill out the stud with my tools put me right off.

Also, I have a deathly fear of drilling into the bottom of the car. You know what lies beneath so it’s not a problem for you but it gives me the heebies!


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Pinkythelabrat said:
I liked that idea and have some of the rubber-type fixings you mention but the struggle of being under a car on jack stands trying to drill out the stud with my tools put me right off.

Also, I have a deathly fear of drilling into the bottom of the car. You know what lies beneath so it’s not a problem for you but it gives me the heebies!


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I agree, it's a squeeze being under the car with just axel stands to give clearance. I've got a nice little right angle drill for my compressor and also a Dremel right angle chuck, so big clearance isn't needed really.

In terms of what's underneath, there's nothing of great importance around the areas you'd be drilling, certainly not within a couple of inches (5cm for those whippersnappers out there!) proximity. You're more likely to cause damage with a slipping drill on the outside, holing the tank or a fuel line for instance.

Wiring all runs along the sides of the car in the sills, so is well out of the way.
 
Skipton01 said:
There's been a few threads on this over the years - rivnuts were seen as the preferred solution it seems.

Personally, I've been thinking of different methods and the one I'll be trying in the near future (when the weather improves) is to grind down the remaining stud, drill out each spot, de-burr, paint/corrosion treat and then use rubber well-nuts with A4 stainless hardware. This will have the benefit of a little physical isolation between the body and the shield, lessening noise transmission and it's also cheaper than getting rivnuts and a setting tool.
Click to expand...
Will the rubber handle the heat? The shield will be hot, and the screw or stud will be too.
Mac.
 
I did exactly this recently, I cant remember the exact fix but I think on mine the bolts had corroded out but they fix into plastic, there was just enough bolt remaining to get some very good mole grips on to the shaft of the remaining bolt out and fit a new one + repair washers as the heat shield holes has ripped/enlarged. On a few I think I just used self tappers +washer in the side of the plastic inset. Not going to win a concourse award but took about 15 mins and was using the stuff I had in the shed (admittedly I do have a lot of useful stuff in my shed).
 
PlasticMac said:
Will the rubber handle the heat? The shield will be hot, and the screw or stud will be too.
Mac.
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At the rear of the car, especiallly on diesel models, the heat of the exhaust will be perfectly fine with rubber well nuts. It’d only be heading toward the centre tunnel and forward of this that the heat build up could prove detrimental, especially anywhere near the manifold.
In short, I’d not worry about it.
 
Pinkythelabrat said:
I imagine the heat experienced will be similar to that on the exhaust hanger.


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I suspect the rubber used for exhaust hangers is designed for higher temperatures than that designed for expansion bolts. Rubber is very flexible term. Mostly not rubber at all.
Mac.
 
Is the diesel tank anywhere near where I am proposing to drill a few holes to blind rivet the foil to the plastic? It looks like the tank sits further toward the front of the car, but want to make sure I don't puncture the tank.
 
Pipewerx FullFlow02.jpg

This is the 42l tank from Tank, when I was having the Pipewerx exhaust made. You can see there's a fair amount of space to the tank from the shield, although there are a few fixing points which are actually tabs that extend from it. Only the very ham-fisted could puncture it I think, but you can judge better from the photo hopefully.
 
cool - great photo. So from this angled shot, the tank is 'below' the axle?

and whilst we're looking at this photo - what is the rectangular box with fluted heat distribution casing - just to right (in this photo) of the silencer?
 
Billy Smalls said:
and whilst we're looking at this photo - what is the rectangular box with fluted heat distribution casing - just to right (in this photo) of the silencer?
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That is a heat exchanger for the diesel lines that run to/from the engine. My understanding is that on the PD type engines the diesel fuel that is returned to the tank can be pretty hot and this is to cool the fuel down before it is reintroduced to the tank.
 
Correct - the fuel tank wraps around the beam axel.

The box you describe is a fuel cooler that is on the return line to the tank, which ensures any excess diesel returns at a cool enough temperature from the fuel pump/engine.
 
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