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

Wed Mar 27, 2013 11:49 am

ok, I am intrigued. I don't think I have one on my ride, I don't know. How can I tell if I have one. There seems to be a debate on whether or not there should be one here

Wed Mar 27, 2013 4:38 pm

porschpow wrote: ok, I am intrigued. I don't think I have one on my ride, I don't know. How can I tell if I have one. There seems to be a debate on whether or not there should be one here

Look under or reach under your bus right above where the stock muffler would be. If you can see the rounded tin then you don't have it

Wed Mar 27, 2013 6:13 pm

airkooledchris wrote: 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.

You are correct. The VW engineers were NOT happy with " pretty sure results" and that is why they concluded after much testing on their part that it was NECESSARY. They didn't just decide to spend time and money producing a part that "might" work.

Wed Mar 27, 2013 7:48 pm

Keith wrote: airkooledchris wrote: 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.

You are correct. The VW engineers were NOT happy with " pretty sure results" and that is why they concluded after much testing on their part that it was NECESSARY. They didn't just decide to spend time and money producing a part that "might" work.

im glad your privy to such testing data. I agree they wouldn't waste the money on all those parts if they weren't required, but I don't think more current data is a waste. ask Jake Raby if he thinks the engineers couldn't have done better on any part of the system.... surely there's room for improvement here and there if your willing to collect meaningful data and not rely solely on assumptions.

Wed Mar 27, 2013 8:10 pm

airkooledchris wrote: Keith wrote: airkooledchris wrote: 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.

You are correct. The VW engineers were NOT happy with " pretty sure results" and that is why they concluded after much testing on their part that it was NECESSARY. They didn't just decide to spend time and money producing a part that "might" work.

im glad your privy to such testing data. I agree they wouldn't waste the money on all those parts if they weren't required, but I don't think more current data is a waste. ask Jake Raby if he thinks the engineers couldn't have done better on any part of the system.... surely there's room for improvement here and there if your willing to collect meaningful data and not rely solely on assumptions.

Oh my.

My real-world experience with that heat shield is that it became a big heat "sink" that blistered the paint off my rear engine tins when in place. I had driven oh say 350,000 miles on the Road Warrior without one when I thought to find, pay for, and install the shield because everybody knows that it is there to shield the tins from the heat and I just love to drive through the heat when I can.

I am not one to say that the factory engineers didn't know what they were doing. Yet, the damn shield blistered the paint off my rear tins! It made no sense. Apparently, when I am driving in the desert on a scorcher of a day, shieldless airflow does a good job of cooling the rear tins. When I would stop, the muffler seemed to cool down more rapidly than the heat soak coming off it could damage the 500* universal black paint on my rear tins.

With the heat shield in place and all heated up, there was more stored heat to bake the rear tins during heat soak. That is my guess. I removed the shield on the Road Warrior once more and finished the last 150,000 miles or so with no more blistering of the rear tins. I put HVAC tape on the middle rear course of the foam seal and it held up fine.

I now have a '78 original bus with the original heat shield in place. I don't like the constricted area above the muffler much, but I am keeping it original.
Colin

Wed Mar 27, 2013 8:38 pm

Amskeptic wrote: airkooledchris wrote: Keith wrote: airkooledchris wrote: 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.

You are correct. The VW engineers were NOT happy with " pretty sure results" and that is why they concluded after much testing on their part that it was NECESSARY. They didn't just decide to spend time and money producing a part that "might" work.

im glad your privy to such testing data. I agree they wouldn't waste the money on all those parts if they weren't required, but I don't think more current data is a waste. ask Jake Raby if he thinks the engineers couldn't have done better on any part of the system.... surely there's room for improvement here and there if your willing to collect meaningful data and not rely solely on assumptions.

Oh my.

My real-world experience with that heat shield is that it became a big heat "sink" that blistered the paint off my rear engine tins when in place. I had driven oh say 350,000 miles on the Road Warrior without one when I thought to find, pay for, and install the shield because everybody knows that it is there to shield the tins from the heat and I just love to drive through the heat when I can.

I am not one to say that the factory engineers didn't know what they were doing. Yet, the damn shield blistered the paint off my rear tins! It made no sense. Apparently, when I am driving in the desert on a scorcher of a day, shieldless airflow does a good job of cooling the rear tins. When I would stop, the muffler seemed to cool down more rapidly than the heat soak coming off it could damage the 500* universal black paint on my rear tins.

With the heat shield in place and all heated up, there was more stored heat to bake the rear tins during heat soak. That is my guess. I removed the shield on the Road Warrior once more and finished the last 150,000 miles or so with no more blistering of the rear tins. I put HVAC tape on the middle rear course of the foam seal and it held up fine.

I now have a '78 original bus with the original heat shield in place. I don't like the constricted area above the muffler much, but I am keeping it original.
Colin
I am wondering if the paint on your tins was not high quality or not properly prepped? My 72 has had the shield for 110,000 miles and the original tin paint has not suffered from it. Just throwing out a possibility

Thu Mar 28, 2013 5:55 am

Well, I looked around with no luck. Anybody have a heat shield for a 73 bus laying around??? :?:

Thu Mar 28, 2013 12:35 pm

porschpow wrote: Well, I looked around with no luck. Anybody have a heat shield for a 73 bus laying around??? :?:

Saw this in the classifieds.

http://www.thesamba.com/vw/classifieds/detail.php?id=1388269

Thu Mar 28, 2013 12:42 pm

Yeah, it is for a 76, not sure if it is compatible. So the round part on that shield contours to the fan tin?

Thu Mar 28, 2013 4:28 pm

amskeptic, I have never had a bus w/ the heat shield, but I finally got a cruddy one that I need to add some legs to soI can mount, since I feel confident it will work better than a home made one, which could sufffer from making a dead spot in air flow right there and trap heat, where as the VW one I am sure works better than I can make mine work with out a wind tunnel! :lol:

My point is tho, assuming your conclusions are correct and a parked hot heat shield bakes the tins worse than a motor without, I don't really care! Cause if the heat shield works at speed, keeping the average temp of the engine cooling air lower than without, and only bakes the engine during cool down, that sounds a lot less detrimental to engine health than having the average running temp higher w/o it, but lowering the peak temp the tins see. Which they only see once parked.

my armchair engineering quota for the day has been filled.

Thu Mar 28, 2013 5:27 pm

porschpow wrote: Yeah, it is for a 76, not sure if it is compatible. So the round part on that shield contours to the fan tin?
Yes. 72-79 should use the same piece.

Thu Mar 28, 2013 5:27 pm

fusername wrote: Cause if the heat shield works at speed, keeping the average temp of the engine cooling air lower than without, and only bakes the engine during cool down, that sounds a lot less detrimental to engine health than having the average running temp higher w/o it, but lowering the peak temp the tins see. Which they only see once parked.

my armchair engineering quota for the day has been filled.

Ouch, my head hurts. I have no idea. I can only report my experience.
What is my experience? I'll summarize:
I love driving in insane heat.
I have never blown up a VW engine.

I will report the minute this changes . . . the way this Universe seems to work, I will most definitely be posting here some day, "I dropped a valve, I am in Furnace Creek, anybody got a spare engine pleeeeze?"
Colin

Thu Mar 28, 2013 5:42 pm

CoastalAirCooledVW wrote:
I am wondering if the paint on your tins was not high quality or not properly prepped? My 72 has had the shield for 110,000 miles and the original tin paint has not suffered from it. Just throwing out a possibility

I don't doubt that the factory original paint has better staying power.

I used Duplicolor Engine Enamel that gave me 6 years and 123,000 miles. RIOMX might be able to give you an update on how that paint is holding up now that he has my old engine somewhere on this Earth:

February 2003 @ 435,000 miles

Last Engine Out pic April 2009 paint still OK a little dusty at the front of the engine where i was doing a pilot bearing pull:

Thu Mar 28, 2013 7:07 pm

One if you should go to your local discount store and get a wireless indoor and outdoor thermometer. Then you can compare the compartment temperatures with the heat sheild and without.

Thu Mar 28, 2013 10:27 pm

reluctantartist wrote: One if you should go to your local discount store and get a wireless indoor and outdoor thermometer. Then you can compare the compartment temperatures with the heat sheild and without.

I had an infrared thermometer and it showed not a damn bit of difference *while running*.
Ambient temp 118*
fan housing temperature 127*
left side of muffler 480*
I don't have any other readings of local sheetmetal, because at the time I did not care about all that because the engine was running FINE for its 28th year in my care. That's the thing.

Once your engine has told you that it is happy, you don't keep hunting down every little thing. I have had happy VW engines. My one and only heat-trauma was with the 1970 getting some nasty 430* CHTs. I was ready to blame the:
power circuit in the carburetor
lack of deflector plates in the heads
timing
main jet
fan size
flaps bent
dragging brakes
gaps in engine seal
some ridiculous vacuum leak or sumpin'

I would have gladly listened to any number of speculations, but I finally had to do a Big Investigation, on the road so I bailed at James Dwan's house in Dallas area, and found the One True Cause.
the machinist for the prior owner's rebuild, had accidentally installed fuel injected beetle exhaust valves ( 2mm too small a diameter!) that were riding on their edges and slowly sinking into the seats. Horrendous!

Slapped some used heads on, caked with off-roading mud, also missing the deflectors, running 80* cooler with all of the above issues still the same. Ran it through Death Valley last July. Bus didn't care. 17,000 additional miles on the used heads and they are running fine. They just don't care. Therefore, neither do I.

So now, I am less desperate about every little thing. There are too many variables. If your engine is happy, well, be happy. I have seen Type 4 engines violate every rule I ever suggested and refuse to run hot, I have seen some real princesses where everything looked perfect, and they ran hot.
Colin

Fri Mar 29, 2013 12:12 am

I am gonna sandwich mine with fiberglass impregnated silicone. Inside and out blasted,braised and coated.

Wed Jun 12, 2013 11:13 pm

So what is the consensus on these? Anyone running DD's and has real time data?

Wed Jun 12, 2013 11:23 pm

Hoody wrote: So what is the consensus on these? Anyone running DD's and has real time data?

You will survive either way. My bus is still wearing its factory shield and always will be. Is it better? I dont know, but that is how it has always been and that is how it is always will be until someone can prove that it is bad. Maybe I will do some testing since I do have one of those temp guns :-k Stay tuned, I might do some testing. I will have to do the exact same drive twice at the same speed which might be difficult but we should get a general idea

Thu Jun 13, 2013 12:24 am

Still running the DD's Colin?

Thu Jun 13, 2013 4:50 am

My CHT's (DD) are running the same as before I installed my heat shield this spring.