Charcoal canister replacement.

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T.Hanson
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Charcoal canister replacement.

Post by T.Hanson »

Purolator charcoal canister 00701 for sale on Ebay for $95 without the foamy bottom circle.

Just for grins, what might happen if I clean up, paint nice the one that's been filtering the charcoal for 35 years ?
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Lenny D.
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Post by Lenny D. »

Point is, you don't know if it's ever been overfilled and drowned by a PO.

As Mike has pointed out, what toasts these emissions control devices from the late '70s is 'topping off' with gas that sends raw liquid fuel to the canister, drowning the charcoal. The charcoal is there to absorb and hold only fuel vapor from the raw gas in the tank, then sucked into the intake upon startup, removing the vapor until the next batch - at least in theory. It works until the charcoal can't absorb any more vapor.

In late model aircooled VWs we would take the canister apart (pressed together pieces of metal) and replace the charcoal with the stuff you get at an aquarium shop for about 2 bucks, then reseal the body. IIRC, our cars have a foam material bottom and that may be all that holds the charcoal in the body. It's been a looong time since I did this, but the point is to replace the charcoal, however you can. Then you can paint it up pretty and smile that you didn't pay exorbitant price for a few bucks worth of carbon.
HTH

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T.Hanson
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Post by T.Hanson »

Thank you, I've decided to save up the coin to buy a new one. The oldie has a crimped steel bottom, with holes that look too small to attempt shaking out the old charcoal bits, or bend a can opener and buy Gorilla Glue to allow replacing with fish bits. I have my limits for delusions of thrift.

It's all so confusing; from this early tech charcoal filter, oxygen sensor clean air solution, morphing to corn blends, that eat things, to no more emissions inspections in more than a few states, to batteries in little cars that weigh 3,000 pounds and have computers in charge of stopping them short of the trunk ahead in case the driver is busy snacking and texting.
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Lenny D.
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Post by Lenny D. »

T.Hanson wrote: It's all so confusing...
They are just making it up as they go along... :o
HTH

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CabbageFumes
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Post by CabbageFumes »

Lenny D. wrote:Point is, you don't know if it's ever been overfilled and drowned by a PO.

As Mike has pointed out, what toasts these emissions control devices from the late '70s is 'topping off' with gas that sends raw liquid fuel to the canister, drowning the charcoal. The charcoal is there to absorb and hold only fuel vapor from the raw gas in the tank, then sucked into the intake upon startup, removing the vapor until the next batch - at least in theory. It works until the charcoal can't absorb any more vapor.
Ok, hold on, this is completely wrong.

Fuel isn't fed to the canister by topping off the fuel tank, and it doesn't function as you describe even remotely.
The canister is in the front of the car, away from the fuel tank. It only acts as a "purifier" as part of the EGR system. Excess vapor is allowed to escape from the intake manifold through a valve, which then travels to the canister. Vapor is partially bled to the atmosphere through the charcoal, the majority routed back to the expansion tank in the trunk, then back to the fuel tank. In the scenario above, fuel would have to travel up from the fuel tank to the expansion tank, filling it, then forward to the engine compartment to the canister, "drowning" it, then to the engine.
Sorry buddy, not even close to how it works.
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cory58
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Post by cory58 »

CabbageFumes wrote:Ok, hold on, this is completely wrong.
Interesting coincidence - Mike Miller answered a question about fuel smell in a 2002 this month in Roundel. Here is the text.

If the smell is raw gasoline: That probably originates under the hood. Does your 1972 2002tii have the evaporative emission control system? If it does, there will be a plastic expansion tank located in the trunk above the right rear wheel hous­ing. There should be an activated-char­ coal canister mounted in the engine compartment. The activated-charcoal canister, if it is still correctly plumbed, is most likely not working, and it contains raw gasoline because someone topped off the fuel tank too often. Sean can blow the system out with air-and you probably need a new canister. Make sure it's plumbed correctly and that the vacuum hoses aren't cracked or broken. Notably, the engine might run an eentsy-beentsy bit richer once it's breathing gasoline fumes. I can usually lean out carbureted M1Os a little bit once the EVAP system works again. Incidentally, this is one part of emission control systems that does not affect performance, and to the extent it does, it is a positive. The only downside here is the canisters are now only available from BMW -and they cost $100. I remember when they were eight bucks and Michel Potheau would ask me, "What the heck
do you want these things for?" I miss that guy.


I'm still learning E12s. Previously, my oldest Bimmers was a 1988 E30. Does this mean that Mike Miller is disagreeing, or is the charcoal canister plumbed differently in a 2002?

Cory
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1988 320i Touring (euro)
1992 325i Cabrio
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CabbageFumes
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Post by CabbageFumes »

cory58 wrote: ...the charcoal canister plumbed differently in a 2002?

Cory
Yes.
That scenario is specific to the 2002 because of the way the system is plumbed, so what happens is what I mentioned about the expansion tank would have to be filled, then forward to the canister. In the 2002, it is a perfect storm situation when you fill the tank up to the very top, which is where the vapor return hose in the filler neck is. That's not the case with an e12 because even though the components in the system are basically the same, there are safeguards in the way they laid out the system to prevent it. My post was e12 specific, so ya can't blame me if some other model was planned poorly.
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cory58
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Post by cory58 »

CabbageFumes wrote:
cory58 wrote: ...the charcoal canister plumbed differently in a 2002?

Cory
Yes.
That scenario is specific to the 2002 because of the way the system is plumbed, so what happens is what I mentioned about the expansion tank would have to be filled, then forward to the canister. In the 2002, it is a perfect storm situation when you fill the tank up to the very top, which is where the vapor return hose in the filler neck is. That's not the case with an e12 because even though the components in the system are basically the same, there are safeguards in the way they laid out the system to prevent it. My post was e12 specific, so ya can't blame me if some other model was planned poorly.
Thanks for the E12 lesson! I think I'll be in the steep learning curve phase of E12 ownership for a while.

Cory
1977 530i
1988 320i Touring (euro)
1992 325i Cabrio
2000 M5
2015 328i (wife's daily)
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