1972 911T MFI heat exchanger hoses

[47silver]

i am stumped on what to get for the hoses that connect from the heat exhanger to the engine tin on a 1972 with mfi
i have the right pipe for the 2 large outlets in the rear of the engine one connects to the fan duct and one to the filter warmup device
there are 2 smaller tubes #1 is up by the neck of the heater exchanger and #2 is on the heat exchanger pipes which feeds air to the filter warmup device
does anyone have part numbers?
Photo bellow

[47silver]

[kennykimk2]

I used same hose you put on Crankcase Vent.
Have a pic, but my iPad will not allow me to upload.
Send me a pm with your email addy and will send you the pic, if you want.

[47silver]

thanks, I found a photo that shows a rubber hose from the small connection at #1 to the small connection on the engine tin...

from what I can see there is nothing connected to #2, it relies on the intake to draw in air, there is a screen on the outlet side that goes to the filter housing regulator
I am good to go.

[Flat6pac]

#2 is considered the “Street Sweeper” and a hose is suposed to run through the rear tin to the flapperbox on the intake in 72/73.
Lots were removed because it brought too much dust and dirt into the air cleaner.
Bruce

[Daves911L]

The small hose going from the heat exhanger fitting to the thermostat is (or was, anyway) not rubber. An odd double layered thing, like a hose within a hose. I assume this was to insulate it against heat loss, and get the thermostat up to temp quickly. It looked just like the aluminum/paper hoses, but was more like plastic/paper.

The duct from the "mini" heat exchanger to the cold air flapper was aluminum/paper. but smaller diameter than the normal heater tubes. If memory serves (fails more often now!) VW heat ducts may be the right size. You surmised its function accurately.

[47silver]

would it make sense to open the flapper on the intake regulator but to leave all the hose intact? I suppose it is used for warm-up purposes, and I doubt I will be driving it much in the winter.

[cmcfaul]

Put it all back together the way Porsche intended. It's just hoses (strange ones) but the Porsche engineers did it this way for a reason and MFI does not like to be messed with. One hose goes to the thermostat. The other goes to the flapper box. They both help the car warm up and properly control the mixture according to environmental conditions and engine temp. Once you start deleting parts its down hill for value and performance.

Chris
73 E

[47silver]

the car is going to have everything as it left the factory.

[mobius911]

Pretty sure#1 in OP's diagram is 999.181.212.50, often referred to as "steam hose"- a thick rubber hose. Not sure it's still available from Porsche, so some people really do source "steam hose" as a replacement. It connects the upper left side heat exchange nipple to a fitting that connects to the MFI pump thermostat hose.

#2 is 911.110.295.02. Should be available from our host. It's just a short length of flexible metal hose that connects from a nipple on the heat exchanger to a corresponding vent nipple on the left side engine tin. It just vents into the engine compartment and I guess is intended to speed warm-up. No hose clamps are spec'd for this one; just friction fit.

[47silver]

item#27 is the steam hose that is required from the small tab at the neck of the heat exchanger to the engine trim: it is now part#00004320521
from the engine tin to the mfi thermostat you need 2 hose, look closely you will seen that item#28 and 29 are a hose within a hose.
part numbers are: 90111029500 for 28 and PCG11029600 for 29

from the heat exchanger directly to the filter heat regulating device you need part#91110815100, which is item#27 in the diagram of the heat exchangers above.
so all told to get new hoses (not including the normal heat hoses you need:
00004320521
90111029500
PCG11029600
91110815100

[mobius911]

Just to be clear, here is a photo of a left side heat exchanger from another thread. This may be a 73 only thing, but the red circled nipple takes hose 911.110.295.02 (may be superseded). I thought you were pointing to that in number 2 in your OP. The part is shown in that drawing as #34.

A 72 may be different, but the 73's do have this hose.

[47silver]

I do not think that #2 pipe gets a hose, it is open to the atmosphere and that is why someone called it a street sweeper as the outlet end connects to the filter and is open to the filter when the air temp is low.

[pwd72s]

A top view for you...box stock 1972 911S

[florio]

Having studied this in detail, I can confirm what 47Silver is stating. The small hose to the MFI pump is cardboard with a metal liner, and there are two of them (ordered separately) that fit one into the other. The two then get crushed together at the ends where you attach them, creating a closed cavity. The idea is that this will insulate the air from the engine against the outside cold, and bring the thermostat on the pump up to the temp of the cooling air from the engine. The flapper box assembly is to bring in warm air into the engine while it is warming up. The hole circled in red is the air intake for the engine while it is warming up.
good luck!

[47silver]

There is a screen on the hot air pipe going to the cold weather valve on the filter housing to protect against infiltration of leaves. Mine was deteriorated and needs replaced. If that us missing the engine coukd vacuum debris into the air intake.
The part numbers above are what is required to connect the mfi, filter, engine tin and heat exchangers ilk post some photos.