Charcoal Cannister Filter - Do I need it?
 

Hello all,

I'm currently pulling my 86 Targa apart to do some rust repair and repaint. When I was busy tearing things apart last weekend I came across the charcoal cannister in the right rear wheel well. The bracket holding it in was about to come apart as it was rusted out so I decided to pull out the assembly. One of the studs broke off in the process and I found a nice rusty hole behind the cannister that I'm going to have to deal with, see the pic below;

http://forums.pelicanparts.com/uploa...1274321647.jpg

And a closeup

http://forums.pelicanparts.com/uploa...1274321667.jpg

So the first question is whether I need to reinstall the charcoal cannister. Since the old one is 23 years old I pitched it figuring that a new one is probably a good idea (probably a dumb move but that day was a loooong day leading to some rash decisions at the end).

If I don't need to install it what do I do with the two hoses that are no longer attached to anything?

If I should reinstall it where do I put it? If I put it back in the same place I will need to deal with the rust patch and weld in a new stud to attach the bracket to. Is my best option to get the same piece that is rusted out in my car cut from a wreck and then weld it in? I'll have to deal with the rust in any case, so this would not add too much more to the work required.

Where else could I install it instead?

Your help will be greatly appreciated.

J

It is part of your gasoline fume recvoery system and is a good idea to have functional so you don't end up breathing a bunch of gasoline fumes from your gas tank.

This should be what your system looks like (thanks Grady for posting this here: http://forums.pelicanparts.com/porsche-911-technical-forum/299053-tank-ventilation-mfi-diagrams.html):

http://forums.pelicanparts.com/uploa...1155823895.jpg

© Dr. Ing. h.c. F. Porsche A.G.


1 – Fuel tank
2 – Expansion chamber
3 – Activated charcoal filter
4 – Cooling fan upper shroud with hose connector
5 – Hose from cooling fan to activated charcoal filter
6 – Hose from activated charcoal filter to engine air filter
7 – Engine air filter
8 – Return hose connecting fuel tank with expansion chamber

OK, I guessed that it was somewhat important as well, however after 23 years activated charcoal won't be filtering out much of anything which makes me wonder whether it was really all that important after all. I'm guessing that others have dealt with this problem for a late 80s vintage car so I'm curious what they have done.

Now assuming I do get another filter where should I put it? The current mounting point is a mess. Should I look for a patch piece with the studs and weld it in and then find myself a new or used bracket? What's my best option?

Let me throw this idea at you... Charcoal canisters aren't exactly rocket science. They are a big dumb lump of plastic with activated charcoal inside that keep fumes from wandering about.

Go to a u-pull wrecking yard and pick up one that's small and has the roughly correct hose configuration (fuel, fuel tank, sometimes there is a third line) as your car had. Look for a small one and that's usually going to be from an import.

For my Dad's 87 Monte Carlo, I retrieved a canister from a Geo Metro. It's bout 5 inches tall, 3 inches thick and maybe 4 inches across and came with a handy mounting bracket. I put it in a hidden spot. Picked it for the size, it was probably half the size of the original one. Works great.

angela

BTW, the charcoal will last just about forever in this application.

Hi J,

I found exactly the same problem with my car, pics here :

Board Message

I have read elsewhere of removing the cannister and all the pipework and fitting a much smaller non return valve under the front fender.

Gwyn.

Quick question for you guys. Which tube that goes to/from the expansion tank is the larger one? Thanks.

Harry, Angela, Gwyn,

Thank you very much for your advice. I like the idea of using a smaller filter. I'm thinking that putting it in the engine compartment to the right of the air box and behind the oil filter might be a good spot, assuming I can find one small enough to fit. What do you think?

I also have the same question as Mike D. Now that I've remove the hoses I don't know what hose would go to which port.

Any thoughts on the rust repair options for the mess I found under the cannister?

J

I am looking at reducing the size of the canister on my 84 also - seems to me this could be handled much better with today's technology with a small non-descript canister...has anyone done this?

The current cannister looks like a scuba tank...

Targamaniac - regarding the rust, you need to pull out grinder and go to town and see what you are dealing with (perforation, surface..or??) After that you can assess if you need some surgery or not.

I would put it at the spot the factory used on the latest iteration of the 911 version you have.

You have an '86 (3.2L DME motor) so either put it where they did on the '87s (maybe same position) or put it right back where it was.

They don't just stick stuff on the car randomly, so unless you do a better engineering analysis than the factory's stable of engineers leave it be. You will also save on fabrication of mounts, hoses, etc.

CARB told me that the canister lasts until it falls apart unless you contaminate it with liquid fuel.

I agree that you can likely use any canister of roughly the same size and hose configuration.

Hmmm, I guess I shouldn't have pitched the old one. I guess I'll retrieve one off of a wreck unless I go with something smaller.

I'll put another one back where I found the original if I can get the mounting point cleaned up. It'll be me and my sandblaster/grinder this weekend seeing how deep the rust hole goes. All I wanted was a fresh paint job but I'm getting so much more education for my money :-)

yes, sorry to see that rust - maybe you can send a bill to the road salt companies...

easiest thing to do is to find one off an '86 or similar at a junkyard or post an ad on the spare parts forum

Good Luck!

Thanks for the advice!! That's why this forum is awesome :)

At least I'll get to practice my welding skills and have an excuse to clean out my wheel wells. There's rust in there around the Targa bar attachment point and behind the seals so I have a fair bit of work ahead.

Take care.

J