Colored hoses, Are they still available? Or has anyone tried dying a hose? Options

[TonyA]

Maybe i ma crazy but are these available anywhere, or has anyone ever attempted to bleach and dye a hose?

[wonkipop]

yes mr. sb. you can't find anything definitive in the factory manual regarding plumbing for the engine bay canister mount for the 74 1,8s on. only the emissions warranty schematic. i'm not inclined to think its a misprint. nor am i inclined to think the earlier pre 74 emissions warranty schematics are a misprint. or that the vw emissions schematics are misprints.

you can find hose layouts for vws, when it comes to factory workshop manual authority.

as noted of interest there is definitive factory manual material on the 911 which demonstrates a change in the plumbing for the 74 model year. the change adopts the vw plumbing which is opposite to the earlier plumbing.
they are responding to something. did their system fail in some way?
it would not be the first time porsche engineering failed, they were not infallible.

the earlier years of 914s have the porsche system matching the 911s.
its a porsche design layout for location and plumbing, not a vw design layout.

why?
i'm less inclined to look for answers inside the can itself as mr. b does.
not that it is wrong to do that.
its just that i prefer to see the whole thing in the context of changing the location of the can as well.
of interest to me is the question of pressure drops in lines, especially over length. i know about that in my line of work so i can see that the porsche long length system would have significant pressure drop - it would result in lower efficiency on the suction draw of the hose to the aircleaner and the ability of the can to purge during operation.

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re the primary function of the can -

i dug up a paper a year back from the University of Colorado published 2003 which gave a detailed account of the history of emissions initiatives/legislation by US EPA.

i know i am a kook to be interested in that stuff, guess thats why i have a 1.8. (IMG:style_emoticons/default/beer.gif)

the heat soak phase of the engine after you switch it off having driven it and its effect on the fuel system of the car was found in the late 60s to cause the most dramatic release of hydrocarbon molecules. that phase lasts approx 1 hour after the engine is turned off. the charcoal cannister evap system universal to nearly all cars was designed with an emphasis on that. the other major vapor escape is during refuel as noted by mr. b when the new fuel displaces vapors that have formed in the tank. day to night expansion and contraction of the fuel is a gentler process and can almost be taken care of by condensation in the line from the tank to the cannister.

the great thing about the system, coupled with the PCV system is single-handly the two things chopped hydrocarbon (big long chain molecules) emission from cars in half just like that. a beautiful piece of simple engineering. when it works.

charcoal cannisters in most cars didn't have a fan feed like vw or porsche.
the bonus of the ducted cooling fan? (IMG:style_emoticons/default/beer3.gif)
they relied on a mechanical valve which opened the can to a passive fresh air feed line.
the suction of the open throttle in the engine provided the draw from the can that pulled the stored fumes out and burned them in the engine. there was no positive pressure as such in those systems, just an air draw caused by suction from the engine itself. the main purpose of the fresh air line is to oxygenate the hydrocarbon molecules. that causes them to be released from the carbon (charcoal). they are not blown off the charcoal so much as flooded with oxygen.

the design of the cans (as shown in mr. b's photos and in some even more detailed threads i came across in the samba site just now) supports the fan feed as an oxygen flooding device. the spring loaded end with the wide perforated filter creating a chamber would allow very efficient oxygen flow dispersal and flooding over the full width of the can. i believe that is why vw plumb the fan feed line into that end of the can.

by having a kind of "supercharged" oxygen flow from the fan vw and later porsche were upping the ante on oxygen flooding? i think the idea might have been to be able to get a faster and more thorough purge of the can when the engine was running?

as we all agree the weak point in the vw and porsche system is no valve. and in the case of the fan line no further filter and a direct route to the atmosphere once the fumes had saturated the charcoal. the fan line has an internal filter over the end of it, but its the same material that is at the other end too over the suction/aircleaner line. (the more universal types of cans in many cars prevented this because they had the mechanical valve as a final closure). the other line to the air cleaner at least has the aircleaner filter additional between it and the atmosphere (not that its 100% effective though, but it is there). and anyway that conforms to all the other manufacturers with the "unassisted" charcoal cans. they too have nothing final between the suction end of the can and the atmosphere but the engine air filter.

what am i saying. mr. b's engineering logic on the workings of the can supports the vw system and the system on the engine canister L Jet 1.8s because the fan line is isolated by the most charcoal from the atmosphere. if the fan line was beside the stump fume inlet then it would be venting fairly easily and fairly quickly once the bottom few inches of the canister was saturated? you have to consider how the system works when the engine is not running because thats when the cannister is doing its job, in the one hour following engine shut down. there is no big air flow in that mode. its just fumes percolating in. and ultimately percolating out of the can once charcoal reaches absorption capacity. at that moment they percolate either straight out the fan hose or straight into the air cleaner hose - where there is one more seal, the air cleaner filter. the more charcoal there is absorbing between the fan hose line and the fume line the better. the shorter distance to the aircleaner line offers a quicker fume route sure, but its still effectively trapped inside the engine by the air cleaner filter and the design of the air cleaner housing. the hose is plugged into the top half of the aircleaner above the filter where they are likely to stay as vapor. fuel vapors tend to collect in the upper section of chambers rather than descend. what has to be kept in mind is that the engine is not running. its just fumes evaporating.

when the engine is running the cannister is in purge mode, or should be. then you can talk airflows. and at that point it isn't about filtering fumes from the air its about burning them in the engine. if anything you want to pull them out of the cannister faster from the location where they are most concentrated. which as at the fume inlet end.

this is my case for mr. b to consider.

i'm saying the earlier system on the 914s and the 911s didn't work.
thats why they got rid of it and changed to the engine bay mount in 914s and vw plumbing.

as to why it may not have worked (as i am (IMG:style_emoticons/default/screwy.gif) and/or arrogantly saying?) , or why it was that porsche alone, at first, plumbed the other way, no one has really explained that fully - its taken that it worked and its authorative when looking at later cars - when it may not be. (IMG:style_emoticons/default/pray.gif) i would say, if it turned out it did not work over the 5 year/50,000 m period it was required to work, it was because of a combination of long lines and pressure drops and the adjacency of the fan feed line to the fume inlet line. it could be it was not discovered for a few years into the warranty period - because the charcoal does have a big capacity to absorb before it finally gets overwhelmed. it may have taken a couple of years for problems to emerge in cars. owners and dealers may have noticed fumes - who knows. but it did have a warranty on it so the EPA would have been taking notice in some capacity.

the same history paper i read talked about how the EPA, particularly in california used to monitor the pollution systems in cars early on before more formal programs were introduced and their budget grew to the size it is today. they used to rent cars apparently and pull them into their workshop and examine them with a view to real world scrutiny. that would have been interesting. there was also it seems a more informal process they first applied when raising issues with manufacturers. only a few of the concerns and responses ever escalated to full scale legal fights between the EPA and manufacturers. chrysler is noted as a manufacturer who liked to get the lawyers out.

back then (and maybe still?) porsche sold a ridiculous % of their output in california alone. if anyone would have jumped for the EPA it was porsche. probably would have even jumped at a shadow.

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@ starbear - i like your description of the 1.8 as a "criss cross" plumbing system.

the vapor feed line might play a part in that since having to get to the back of the car in the engine can system its just ran beside the fuel lines and enters the engine bay in the same place on the rhs. seems to set up the orientation of the can, as if they did not want to loop that line out and around in the engine bay but were happy to loop the others.