TheSamba.com :: View topic - type-4 heat shield

Tue Jun 19, 2012 10:59 am

when i first looked at these
i thought to myself that some dumb ass PO
cut the end off one of the shield

but while i was clening them i noticed the short shield
is not hacked and is factory made to have a shorter end

the question is
have any of you veterans noticed this before
and what year modal could require the shorter end

at first i thought it might be shorter for the a/c compressor
but the shield does not go that far to the left in the first place

the only other reason i could come up with is
the preheat tube on 75-early 76
or the heater box inlet on 79 ca (driver side)

ive had these for a while trying to figure out and confirm
why 1 of them is shorter on one side

ant thoughts would be great.............

Tue Jun 19, 2012 11:03 am

Both of my 79CA has that same thing.

Tue Jun 19, 2012 12:29 pm

Here's the original shield from my 1979, if that helps you to figure out which is which.

Tue Jun 19, 2012 12:32 pm

If you have a spare, I'd be happy to take it off your hands :)

Tue Jun 19, 2012 1:41 pm

so then its confirmed....

the short heat shield is specific for a 79 ca

thanks guys

Tue Jun 19, 2012 2:28 pm

vw76westy wrote: the short heat shield is specific for a 79 ca

Probably not just a CA model though. Mine is a Federal 79, and has the short shield.

Tue Jun 19, 2012 4:18 pm

Manfreds78bay wrote: If you have a spare, I'd be happy to take it off your hands :)

Ask and you shall receive:

http://www.thesamba.com/vw/classifieds/detail.php?id=1321568

Tue Jun 19, 2012 7:14 pm

I learn sooooooooooooooooooooo much from you guys. :)

Tue Aug 14, 2012 11:33 am

i thought it would be pretty cool to add

the type-4 heatshield to this thread
thats 411 -412 type-4

as you can see its the exact same size only without the notch on the end

i have not checked to see if it will fit in a bus, since it does not have the notch

i guess this will be the unofficial thread for type 4 heatshields

are there any others out there that are almost but not quite the same
as the 72-78 shield

Tue Aug 14, 2012 12:03 pm

haven't people since decided that these things just trap heat more than they actually 'deflect' it?

Tue Aug 14, 2012 12:15 pm

airkooledchris wrote: haven't people since decided that these things just trap heat more than they actually 'deflect' it?

never heard that one before

if you dont have this shield
the only thing between the air intake (for cooling) and the
very,very hot air from the crossover pipe & mufflar is a tin piece

the shield creates a wall between the hot exhaust and the air intake(for cooling)
it looks like it would also keep the hot air around the exhaust flowing out the back insted of flowing up (making that 1 piece of tin hotter)

Tue Aug 14, 2012 1:43 pm

vw76westy wrote: airkooledchris wrote: haven't people since decided that these things just trap heat more than they actually 'deflect' it?

never heard that one before

if you dont have this shield
the only thing between the air intake (for cooling) and the
very,very hot air from the crossover pipe & mufflar is a tin piece

the shield creates a wall between the hot exhaust and the air intake(for cooling)
it looks like it would also keep the hot air around the exhaust flowing out the back insted of flowing up (making that 1 piece of tin hotter)
News to me as well, it helps with all those things and extends the life of the foam seal dramatically.

Tue Aug 14, 2012 6:06 pm

Has anyone made an after market shield? I have 2 that are shot, and it looks like asbestos between the layers. How much difference would it make if the shield was made as a single layer out of Stainless? Maybe not as good but better than nothing and last a long time.

Tue Aug 14, 2012 6:36 pm

airkooledchris wrote: haven't people since decided that these things just trap heat more than they actually 'deflect' it?

I think it was Colin that made that claim, but may be wrong.

babysnakes wrote: Has anyone made an after market shield? I have 2 that are shot, and it looks like asbestos between the layers. How much difference would it make if the shield was made as a single layer out of Stainless? Maybe not as good but better than nothing and last a long time.

I have rebuilt some that were in pretty sorry states. I just used two layers of sheet metal and left an air gap between them. Seemed to work just fine and without the asbestos to hold moisture have lasted pretty well.

Wed Aug 15, 2012 1:02 am

i got a heatshield
opened it up, got rid of the asbestos
painted the metal inside and out with header paint

put a layer of firewall material in place of the asbestos
then put it back together replacing the spot welds with bolts
reclamped the edges and its been holding storng for the last couple
years

the firewall material is some type of neoprene material
that i picked up at the local vintage car swap meet (pomona swap meet)

Wed Aug 15, 2012 5:21 am

airkooledchris wrote: haven't people since decided that these things just trap heat more than they actually 'deflect' it?

Amazing the misinformation that gets posted: Here is a simplified explanation. The heat shield is mounted horizontally in-between the rear part of the engine compartment an the hot muffler/crossover pipe. The heat emitted upward from the exhaust components as infrared energy and absorbed into the heat shield. The heat shield then emits the absorbed energy in all directions from its surface. Since it is flat, and mounted horizontally, roughly 50% of the infrared energy is emitted back toward exhaust components and 50% is emitted toward the engine compartment. Only half of the emitted heat form the muffler crossover reaches the tin at the rear of the engine compartment, which then absorbs/re-emits the heat in the same manner as the heat shield.

Timatt
'79 CA Westy

Wed Aug 15, 2012 8:10 am

timatt wrote: Only half of the emitted heat form the muffler crossover reaches the tin at the rear of the engine compartment, which then absorbs/re-emits the heat in the same manner as the heat shield.

Timatt
'79 CA Westy

Since the heat shield contains some insulation much less heat is available to be radiated upwards, and since even the bottom of the shield will never get as hot as the muffler the amount of radiant heat would be much less even without the insulation.

Wed Aug 15, 2012 9:36 am

it would certainly be an interesting thing to test to get real results from rather than assumptions.

I have never had one in a bus so I can't say how well it might work.
What I can say is that when the rear bumper is hot as hell from being close to the muffler - the tin in front of the cooling fan is still cool to the touch.

it would be a good test to do a specific run twice, once with and once without the shield in place - and use an IR thermometer on that tin in front of the cooling fan after both passes to compare the results.

Wed Aug 15, 2012 10:16 am

airkooledchris wrote: it would certainly be an interesting thing to test to get real results from rather than assumptions.

I have never had one in a bus so I can't say how well it might work.
What I can say is that when the rear bumper is hot as hell from being close to the muffler - the tin in front of the cooling fan is still cool to the touch.

it would be a good test to do a specific run twice, once with and once without the shield in place - and use an IR thermometer on that tin in front of the cooling fan after both passes to compare the results.

im pretty sure the vw engineers already made that test
and concluded that asbestos filled tin had to be made

Wed Mar 27, 2013 10:44 am

vw76westy wrote: airkooledchris wrote: it would certainly be an interesting thing to test to get real results from rather than assumptions.

I have never had one in a bus so I can't say how well it might work.
What I can say is that when the rear bumper is hot as hell from being close to the muffler - the tin in front of the cooling fan is still cool to the touch.

it would be a good test to do a specific run twice, once with and once without the shield in place - and use an IR thermometer on that tin in front of the cooling fan after both passes to compare the results.

im pretty sure the vw engineers already made that test
and concluded that asbestos filled tin had to be made

im pretty sure VW engineers weren't happy with 'pretty sure' results. it would still be a good test to do. I finally have one of these shields, so if I make it to HF anytime soon ill pick up an IR thermometer and get some numbers for us.