Airbox pre-heat air hose missing?

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ChickenPinz
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Airbox pre-heat air hose missing?

Post by ChickenPinz » Fri Mar 27, 2020 9:07 pm

My 710K doesn't have this hose, and the port on the heater box (bottom of image) appears to be blocked off. Did some vehicles not get this hose or is mine missing something it should have?
heated air hose.JPG
heated air hose.JPG (162.31 KiB) Viewed 1438 times
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rmel
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Re: Airbox pre-heat air hose missing?

Post by rmel » Sat Mar 28, 2020 10:32 am

Most likely the PO removed it due to a rotten hose.
I removed mine on the 712 for the same reason AND
it's just not needed in the moderate climate we are in.
I also removed the airflow valve at the throat of the
carb intake.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

ChickenPinz
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Re: Airbox pre-heat air hose missing?

Post by ChickenPinz » Sat Mar 28, 2020 4:23 pm

My guess is that this vehicle has a new heat exchange, and now gets the warmed air directly from that rather than a side-tap of what goes to the passengers. Does that sound correct, that vehicles came with different versions of the heat exchanger (GR 155), as suggested by the exploded view drawing?
IMG_20200328_135902 (Large).jpg
IMG_20200328_135902 (Large).jpg (381.15 KiB) Viewed 1404 times
IMG_20200328_135853 (Large).jpg
IMG_20200328_135853 (Large).jpg (456.64 KiB) Viewed 1404 times
30-05 heater (zoom in).JPG
30-05 heater (zoom in).JPG (59.25 KiB) Viewed 1404 times
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rmel
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Re: Airbox pre-heat air hose missing?

Post by rmel » Sat Mar 28, 2020 4:27 pm

The smaller diameter hose from the HE goes back to the air intake for the carb's.
There's a weighted butterfly valve in there that drops at low RPM taking warmed
air in, at higher RPM the weight is overcome and air comes from the open area
under the doghouse. I deleted all this given it was bad and not in a cold climate.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

ChickenPinz
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Re: Airbox pre-heat air hose missing?

Post by ChickenPinz » Sat Mar 28, 2020 4:39 pm

Yes, that's how it's all hooked up.

My question to the group is if there are two different heat exchanger options as the drawing suggests. I'm pretty air-cooled engine savvy (VW and multiple aircraft), so I know the science and purpose of the connection, but Pinz-specific things are new to me so thus the question.

My theory is either the air box near the rear cylinder or the heat exchanger has been changed from factory-original.

Oh, and I'm keeping the parts that the wise Steyr-Puch engineers crafted as our high Sierras aren't unlike the Alps. :)
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rmel
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Re: Airbox pre-heat air hose missing?

Post by rmel » Sat Mar 28, 2020 5:45 pm

I think you must have the thermostatically controlled warm air valve on your
Carb air manifold -- right? And not the weighted butterfly valve. At least
on my 712 there are two ports on the HE. One on the inboard side taking
pre-heated air under pressure from the engine, and one output for cabin
heating. Along the way to the heater flow valve to the cabin there is a port
for a smaller diameter hose to go to the air intake of the carb. -- the
weighted butterfly I mentioned.

What I see you have is the 3 port option. The 2'nd output port should go to
a thermostatically control flow valve for mixing warm/cold air to the air intake.
And with that the port you mention that is blocked should be.

My guess is your Pinz was configured for colder climates.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q

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pcolette
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Re: Airbox pre-heat air hose missing?

Post by pcolette » Sat Mar 28, 2020 11:29 pm

The first photo of the engine is a photo I posted on another thread of the engine in one of my other Pinz's. It did indeed have the thermostatically controlled warm air intake for the carbs. I installed that Styer factory revision and the new hose. Here in Wisconsin the improvement was noticeable during the winter. The carbs also had the appropriate choke plate (#2) and jetting for the northern climates. The tropical choke plate (#6) worked best for the southern US.
Paul C.
_________
'73 Swiss 710M
'89 Puch 230GE
2002 MB G500 (For Sale)

ChickenPinz
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Re: Airbox pre-heat air hose missing?

Post by ChickenPinz » Sun Mar 29, 2020 3:45 pm

As noted, on mine the lower intake opening on the air intake housing goes to the heat exchanger port as pictured.

My question is, again, why there is what appears to be an unused port (circled in green) on the heater valve box that is now blocked closed?

The air intake is connected to the heat exchanger (as pictured) through the hose marked with purple. It seems like a vehicle would be either:
- ported heater valve box (what I have, green circle) + heat exchanger without engine intake air port (teal, not what I have)
*OR*
- unported heater valve box (not what I have, red circle) and the heat exchanger with the air intake port (yellow, what I have)

but not mix of both.

That's what I'm trying to figure out as the combination seems unexpected since there are heater valve boxes without the engine intake air ports.
port and hose.JPG
port and hose.JPG (103.44 KiB) Viewed 1282 times
heat exchanger.JPG
heat exchanger.JPG (144.42 KiB) Viewed 1282 times
air intake.JPG
air intake.JPG (168.44 KiB) Viewed 1282 times
drawing options.JPG
drawing options.JPG (67.97 KiB) Viewed 1282 times
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pcolette
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Re: Airbox pre-heat air hose missing?

Post by pcolette » Sun Mar 29, 2020 5:24 pm

Hard to say why they (Styer) would have assembled yours the way that they did. I think you are correct that it should be one or the other. I've had five 710M's and all had the valve box and the 2 -hole HE. Not that that indicates anything. Perhaps during assembly of your particular unit they were out of 2 hole heat exchangers so subbed the 3 hole? Or out of the correct valve box?
Paul C.
_________
'73 Swiss 710M
'89 Puch 230GE
2002 MB G500 (For Sale)

Wyothing
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Re: Airbox pre-heat air hose missing?

Post by Wyothing » Mon Apr 13, 2020 6:18 pm

So off the back of that airbox control, one hose goes straight back about 3' and is open at the end. What does that do? Is it an air inlet for the heat exchanger is an outlet or what?

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