Heatshields - replacement of...

Don't use the old Asbestos material, but there are a number of modern heat insulating materials available today that will do the job and not be dangerous to your health. As you are in the UK, I am sure there are suppliers both there and near you in Europe. Good Luck Andy!

 

Here is my question. Are the heat shields around the exhaust necessary? Replacement exhaust manifolds don't have them...especially for the limited driving we do.

 

Good point Chaya! Maybe Jet Coating may be sufficient, in fact on another thread it was mentioned that the coating inside and out helped reduce the heat from the headers.

 

Remember "Euro" cars (non-cat) and US cars (catalycists) have different manifolds, at lest OEM...

Rgds

 

The point of the heat shields varies...

The header wraps can be deleted, but the ones shielding the alternator I would retain.

 

Just bought new from superformance, looks as if they have glassfibre insulation between the 2 sheets of aluminium.

 

A more modern/high tech (and easier to make) solution might be to use a single sheet of Aluminium (for the look) with a sheet of Zircoflex stuck underneath it (on the hot side) .

I stuck some to the underside of the rear luggage compartment a few years back - made a huge difference to keeping the heat from the exhaust out.

ZircoFlex - zircotec

 

I was referring to the goofy soft aluminum thingys that surround the exhaust manifolds...This stuff! The ones that rattle! Can we take these off?
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I have a nice US rear exhaust manifold if anyone is interested. Very low miles. It fits US 308 and 328's. Excellent condition. PM if your interested.
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Yep, its good stuff, been around for a while & well proven.

 

Try motorcycle parts/repairs shops and ask for exhaust packing/wadding.

 

Euro cars dont have that.

But instead they have extra heat shields. In particular there is one which covers the starter motor. Without this, the bare exhaust is very close to it.

 

To illustrate: I lifted this picture out of an E-Bay add from one of the main parts distributors (sorry, I don't remember which one); so sorry for posting it without crediting the one who took it, but this is the OEM euro REAR manifold for four valve engines, QV and 328, and the pic is interesting because you see the shields welded on the pipes; some are here for dampening vibrations.
Note that it is reversed on the pic, because, contrary to US 328, on "Euro" cars (which are non cat) the rear manifold exits on the driver's side, then via a short intermediary pipe the shape of an elbow, into the silencer (muffler)
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Thats right, SB 18-3 covers these, added from 328 no 68973.

The Euro cars have other, separate heatshields.

 

Back to the original post and the link to the Nimbus Lite heat shield material.

Although much different looking that the OEM material my guess is that it is more effective while being lighter. The complex dimples and corrugations not only provide rigidity but also dramatically increase the effective surface area for the purpose of absorption and dissipation of the heat. I think it's a product of more modern production processes available today as opposed to 35 years ago. I wouldn't mind getting a small piece to experiment with.

 

Wouldn't make sense if a metal heat shield was actually touching, would it?

 

Well, Chaya "it's a part of the emissions" as it keeps our headers hot ahead of the thermo reactor muffler (or later CATs)..to lower the unburned CO.

That said, the headers are prone to cracks, so I would argue that cracks tyou can see and repair are better than "cracks hidden".

Euro cars do ont have the feature and work fine.

Wear appropriate safety gear when you put the asbestos into the air....you could also ceramic coat them while they are loose!