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914World.com _ 914World Garage _ Expansion Tank

Posted by: STL914 Dec 6 2005, 11:51 AM

Can the expansion tank be eliminated from ontop of the fuel tank without any dire affrects on the cars emissions or fuel system? Do you need to block off lines to and from the charcoal cannister? Anyone here done that?

Posted by: Joe Ricard Dec 6 2005, 11:59 AM

If you don't mind smelling gas fumes all the time .... Yea go ahead and chuck it.
Really it is not that heavy if that's what you are trying to accomplish

Posted by: rjames Dec 6 2005, 01:16 PM

So does that mean that the smell of gas fumes = a possible fault with
the expansion tank? I have some minor (depending on whether you ask me or the fiance') gas fumage but it disappears after i'm driving around. (air movement probably can account for that though)

The smell is both inside and outside of the car. I have replaced the fule lines but it didn't help.

Maybe they should just make better smelling gas...

Posted by: SirAndy Dec 6 2005, 01:25 PM

QUOTE (STL914 @ Dec 6 2005, 10:51 AM)
Can the expansion tank be eliminated from ontop of the fuel tank without any dire affrects on the cars emissions or fuel system? Do you need to block off lines to and from the charcoal cannister? Anyone here done that?

i took all of it off, no expansion tank, no charcoal canister, no vent hoses. nada, zip and zilch ...

works just fine. now here's what i did to get rid of the fuel smell ...

there's a tiny hose that goes from the filler neck to the expansion tank, this is where your tank "vents".
there's also a quite large transparent plastic drain hose that goes from the overspill tray down past the tank and out the bottom ...
i simply put the tiny vent hose *inside* the plastic drain hose! voila!

now, the only time i get some gas smell is if i have a full tank and i hit a corner hard, which means some gas comes out the vent and drains down and out under the car.

other than that, no fuel smell ...
Andy

Posted by: McMark Dec 6 2005, 01:28 PM

Nice idea Andy. One thing I've noticed is that the big plastic hose often has shrunk over time to where it doesn't quite reach the body at the bottom. Meaning that the fuel spillage isn't quite getting routed all the way out of the car. That might be your occasional smell.

Posted by: blabla914 Dec 6 2005, 08:03 PM

I used a long piece of hose that fits the nipple on the filler neck and made sure it went out the bottom of the car through the hole originally intended for the clear plastic hose. Then I added a hose clamp to the bottom to make sure it wouldn't get pulled back in. This keeps the end of the hose about an inch from the bottom of the car. I have yet to smell gas at any time.

As an aside everyone should make sure their clear plastic tube is exiting the body. If that tube is allowed to drain into the body cavity it will encourage rust where the bulk head meets the floor pan in the passenger side foot well.

Kelly

Posted by: Dave_Darling Dec 6 2005, 08:56 PM

Removing the expansion tank will have an effect on emissions. Fuel from the tank will evaporate, and will escape to the atmosphere. This is a big no-no, and the more through versions of a smog check will find it. The expansion tank and charcoal cannister help to trap those vapors and send them to the intake so they can be burned. They cost zero power, and weigh very little. No point to removing them, I say.

--DD

Posted by: badarse944s2 Dec 6 2005, 10:47 PM

If you live in a state where they check emissions evaporative emissions is part of that. That's why new cars have a huge evap system now. There is no road draft tube. It is all captured. The HC's from the car sitting and fuel evaporating causes smog and other things harmful to the environment. If you live in a state like S.C. no one will ever know but in the not too distant future every state will be checking this and I'm sure those parts are not cheap to replace. If your going to take them off you better hold onto them for later down the road.
Wells

Posted by: JOHNMAN Dec 6 2005, 11:37 PM

On track, the expansion tank will "catch" raw fuel and return it to the tank.

I had tried it without the expansion tank, and we could run fuel out the breather (the small nipple) even with very little fuel in the tank.

I also tried placing the small hose inside the larger hose and I think the problem was worse as a vacuum may have been drawn in the larger drain hose causing fuel to be sucked out of the breather.

I re-installed the expansion tank and now the corner workers don't BLACK FLAG the car for dumping fuel while hard cornering. (This did happen a few times).

You can hear the fuel being drawn back into the fuel tank from the expansion tank when the car is parked after a run session.

Posted by: 9146986 Dec 7 2005, 07:35 AM

QUOTE (Dave_Darling @ Dec 6 2005, 06:56 PM)
Removing the expansion tank will have an effect on emissions. Fuel from the tank will evaporate, and will escape to the atmosphere. This is a big no-no, and the more through versions of a smog check will find it. The expansion tank and charcoal cannister help to trap those vapors and send them to the intake so they can be burned. They cost zero power, and weigh very little. No point to removing them, I say.

--DD

I'm no tree hugger, but I'm with DD here.
IMHO there's few good reasons to leave it off than to keep the fuel evap. system intact. What are you really saving anyway, 3 lbs?

Posted by: Air_Cooled_Nut Dec 7 2005, 08:21 AM

The expansion tank is light in weight. Mine had a broken mounting tab and I thought about tossing the whole thing. But then there were the air lines and charcoal canister which, I'm sure, is about worthless after all these years, and plugging the holes in the engine area...too much work So I busted out my MIG and welded the tab back on, zinc primered it and painted it black, then mounted it back on the car. ALL hoses for the whole shebang were easily found at the local autoparts store (Discount Import Parts in Tigard, off Hall Blvd., for you local yokels) and now she looks great (if you're ONLY looking at the hoses )

Posted by: SGB Dec 7 2005, 08:44 AM

Mine has been off ten years (this is ALABAMA), with lines routed to discharge below, but there is still smell in the garage in the summer. I would put it back on but there is NOTHING inside anymore. Where did it go? Guess it doesn't matter.Anybody ever open one up to refill? I figure you could use activated carbon from a refrigerator filter...

Posted by: bperry Dec 7 2005, 12:16 PM

Here is a new (at least to me) failure. I took of my original outer rocker
panels and low and behold my evap hoses weren't even hooked
up properly. I have no idea how long it has been this way or
if it was ever hooked up properly.
Tubing/Hose isn't long enough to reach. I gues it could have shrunk
over the past 30+ years.

See picture below:
--- bill

Attached image(s)

Posted by: Eddie Williams Dec 7 2005, 12:28 PM

Mine was removed by PO, does anyone have the carbon canister/expansion/lines for sale?

Posted by: lapuwali Dec 7 2005, 01:17 PM

I'm normally completely in favor of keeping an evap system, but I have to say that on a 914, there's little point.

Modern evap systems have valves and such to ensure that the system really is sealed when the car is off. The 914 never had these, and simply used the canister to filter fumes from the tank vent. However, the charcoal doesn't have an infinite lifetime, and has been broken up and disappeared in from most canisters, so now you simply have a tank that vents unfettered straight to the airbox. On oil-bath filters, there's nothing to prevent the fumes from simply going out the airbox snorkel. On paper filters, there's the paper filter, but it's not all that effective at stopping the gas fumes.

IF we still had useful canisters or replacements, I'd agree it's worthwhile to keep all of it. Since most of us don't, venting to the airbox or venting to the ground makes pretty much zero difference while the car is parked. While it's running, having those lines there are useful, since any fumes will be burnt. Having the stock canister there is pointless at all times, however.

Now, if people were to use a canister off a newer car that still worked, then running the tank vents through it would be useful, and would generally work fine whether the car was running or not. So, having the lines that run from front to rear isn't really useful if you have a good canister.

Of course, if you've switched to carbs, the fumes coming off the float bowl vents are enough to render a canister a waste of effort.

The expansion tank is another story. I'd guess that the primary reason it's there is because of the short filler neck, and most cars get away with using the volume of the filler neck has a "tank". What did the early 356 use? Did it have a header or expansion tank?