86 190E 2.3L

Hello, I was wondering about your experiences with the charcoal canister. I replaced the tank after a leak that failed to stay fixed. Then the replacement fuel tank did the same thing, and I realized that it was collapsing. I had tested the vent line with a vacuum pump, and it was not clogged. I blew through the vent valve in both directions. The vent valve seemed to work properly, building a bit of pressure then popping open.

So I thought the venting system was good, but it is not. So I decided that my vacuum pump test was inadequate. The only thing I could think was that the line was damaged or the charcoal canister was bad. I did not see any damage to the line. I looked for a used charcoal canister at the Pick-n-Pull, but found that it was leaking the charcoal pellets out pretty badly. They look like little pieces of mechanical pencil lead. So I didn't get that one. I took apart my car, and found a few grains of the charcoal in one of the ports.

Is it common for the charcoal bits to escape the canister? The one in the junkyard was a 1990, and had bits all up in the line going to the engine. I have heard of moisture causing residue to build up and clog the canisters, but I am just curious, should I go ahead and get a new vent valve as well as a new canister?

Both used tanks that I have bought so far were $100 each, so I wanted to check in and let you know of my travails. The car has been laid up more than I can afford, and my truck is crying out for some attention that I haven't been able to give it.

Since the only canister I could find at the junkyard was no good, I did some quick checks and found one from a BMW 3-series that I think will work nicely. It is a 2 port design with the open bottom for taking in vent air, unlike the Mercedes that takes in fresh air through a tube. And it is small enough to fit. I blew air into both canisters, and the BMW one flows much easier. The one on my car flows, but I believe it is partially clogged.

Let me know what you think. Thanks!

The only time that I have seen collapsed fuel tank on a 190E was after an accident on the left front fender.. damaged the breather line for the charcoal cannister vent.

ANY charcoal cannister that has the correct connection(s) should work.

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I just buttoned it up after installing the BMW charcoal canister like I mentioned. Had the bumper, headlights, and fender removed to gain access to the fender bolts. So far it seems fixed, but it's only been a little bit of driving. While the fuel system was apart, I decided to go ahead and install the new fuel filter I had been waiting to install. It started up after about 10-15 seconds of cranking on the first try after sitting there dry for 2 weeks.

There was no apparent damage or dents anywhere, the purge line was clear (unlike the line from the junkyard 90 2.6). I had to lengthen the line to the purge valve since the new canister sits upright. The BMW bracket and clamp were used, and they fit the existing holes without drilling. I just had to bend the tabs on the BMW bracket slightly in the vice, to fit the contour of the sheetmetal on the 190e. I have some photos if anyone cares to see.

Thanks for the help!
Brian

Yeah, post pics. Most all of the forum members LOVE pictures. Heck, I'll bet that if someone posted pictures of plain ol' pavement, there would be a lot of "hits" (and opinions posted ) on that thread.

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P.S. I'll P.M. you some pictures of my wifes hairy butt.

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Here are the pictures, hopefully they can help others in the future.

Front of the car, shows the bumper and front end removed in order to get to all the fender bolts.

The three ports of the original charcoal canister--the black bits on the floor are the charcoal pellets that came out when shaken.

Last 3 pictures show the installation of the BMW charcoal canister in the left front fender. The fat hose goes to the fuel tank vent line. The skinny plastic tube goes to the purge valve which allows the engine to burn off accumulated vapors.

The bracket of the BMW canister had to be bent slightly to match the contours of the mounting location. I did not have to drill any holes. I did have to come up with some nuts and bolts to mount it. I used some 10mm headed bolts. Be careful pushing the tubes onto the nipples of the BMW canister, they are not all that strong, and mine started to bend a little. It is a good idea to lubricate the hoses before attempting to slide them on.

Also, note the holes next to the canister in the last picture. They are keyhole shaped. This allows you to remove the original canister without having to totally unscrew the mounting screws. The screw heads are on the inside, so you have to access them from above or underneath where there is a small hole, just big enough for a 10mm wrench to loosen the bottom screw. I struggled the most with getting access to loosen them and remove the original canister.

By the way, the original canister sits at more of a horizontal angle than the upright BMW unit.

The BMW canister has an open bottom design with a replaceable filter element. I could not find a suitable element, so I just bought the largest PCV filter element off the shelf at Autozone, and fashioned it into 2 half circles to fit the bottom. There are some prongs on the bottom of the canister that secure the element, and there is also a non-replaceable filter element visible inside the canister screen. I was satisfied with this modification, it is working well.

I have been pulling the cap off the fuel tank to check for negative pressure indicated by air rushing in. There has only been slight positive pressure at times causing a hiss. I know it is air coming out because a few droplets of fuel are pushing out and wetting the filler neck rubber gasket. This is normal according to the shop manual. The vent valve under the tank maintains a slight bit of tank pressure to help deliver fuel to the pump. I confirmed the vent valve was working when I had the tank out by blowing in either direction on the valve. There was a build up of pressure before the valve opened and relieved the pressure.

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