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8rmesse 02-14-2011 03:11 PM

EVAP Canister? question
 
1 Attachment(s)
Hello fellow Airstream enthusiasts. I am a relatively new Airstream owner having bought my former bosses 1988 Airstream 345 back in October 2010. This is my first RV of any kind and I remember when my boss bought it new. He took good care of the old girl and stored it indoors when possible only putting 44,000 miles on her in the 22 years of ownership. I had always admired it but really never dreamed he would ever sell it or that I would be able to afford it but when I decided I wanted a motorhome this is the only thing I wanted to own so I asked and it's now mine. I have been fixing little things here and there and have made a couple of short trips with it and I have been having a blast! I have been enjoying learning from searching and reading the forums but this is my first post.

I have what should be a pretty simple question for someone to answer but I have not been able to find the answer by searching the forums or Google so here goes. In the right front wheel housing in the rear upper corner resides what appears to be the EVAP (or charcoal) canister for the 7.4 gas engine. I noticed the other day that it has a large barbed fitting facing downward with nothing connected to it clearly visible in the attached photo. When the engine is running air is being sucked into the fitting. My question is: Is there supposed to be a hose or filter or anything attached to this fitting? It just seems odd to me that there is a large barbed fitting sucking air without so much as a filter attached to it.

Thanks in advance for your help. I look forward to finding out exactly what is going on with this.:wally:

Keyair 02-14-2011 05:03 PM

First of all...
Congrats, and WELCOME!!!!!!:D
From me... and i am a new kid on this block!

You story sound wonderful, and the girl sounds sweet... 44k miles... WOW!
Please take lots of photos, and post them in the Classic Photo thread!

Ok, on to your question....
Mine is a 84, and has a similar canister in the rear RH corner of the doghouse, and I thought mine was a charcoal canister... On the 84, its not... its a vac reservior for the cruise control it seems...
Pic...
https://www.airforums.com/attachments...9347c9fceb.jpg

I suggest you download a copy of the chassis manual here....
This one is the 1987.. might help..
https://service.airstream.com/files/l...3be6cf5637.pdf

Myrtle lynn 02-14-2011 05:20 PM

Quote:

Originally Posted by Keyair
First of all...
Congrats, and WELCOME!!!!!!:D
From me... and i am a new kid on this block!

You story sound wonderful, and the girl sounds sweet... 44k miles... WOW!
Please take lots of photos, and post them in the Classic Photo thread!

Ok, on to your question....
Mine is a 84, and has a similar canister in the rear RH corner of the doghouse, and I thought mine was a charcoal canister... On the 84, its not... its a vac reservior for the cruise control it seems...
Pic...

I suggest you download a copy of the chassis manual here....
This one is the 1987.. might help..
https://service.airstream.com/files/l...3be6cf5637.pdf

Are those two hose that appear to be cut for the aux heat/ hot water heater? Sorry to get off subject.

Myrtle lynn 02-14-2011 05:21 PM

Quote:

Originally Posted by MEANlowGREEN
Hello fellow Airstream enthusiasts. I am a relatively new Airstream owner having bought my former bosses 1988 Airstream 345 back in October 2010. This is my first RV of any kind and I remember when my boss bought it new. He took good care of the old girl and stored it indoors when possible only putting 44,000 miles on her in the 22 years of ownership. I had always admired it but really never dreamed he would ever sell it or that I would be able to afford it but when I decided I wanted a motorhome this is the only thing I wanted to own so I asked and it's now mine. I have been fixing little things here and there and have made a couple of short trips with it and I have been having a blast! I have been enjoying learning from searching and reading the forums but this is my first post.

I have what should be a pretty simple question for someone to answer but I have not been able to find the answer by searching the forums or Google so here goes. In the right front wheel housing in the rear upper corner resides what appears to be the EVAP (or charcoal) canister for the 7.4 gas engine. I noticed the other day that it has a large barbed fitting facing downward with nothing connected to it clearly visible in the attached photo. When the engine is running air is being sucked into the fitting. My question is: Is there supposed to be a hose or filter or anything attached to this fitting? It just seems odd to me that there is a large barbed fitting sucking air without so much as a filter attached to it.

Thanks in advance for your help. I look forward to finding out exactly what is going on with this.:wally:

I have an 87 and will look to see if anything is connected to it.

Keyair 02-14-2011 05:30 PM

Yes, indeedy, thats where they were cut!

Myrtle lynn 02-14-2011 05:36 PM

Quote:

Originally Posted by Keyair
Yes, indeedy, thats where they were cut!

Didn't feel like dealing with it anymore.? I think it's a great concept. I just got my 345 and not to familiar with it yet. I am sure I will be cutting mine once I have a problem. Lol.

Airslide 02-14-2011 05:43 PM

Welcome MEANlowGREEN!

Glad to have you part of the forums...

Vinnie

8rmesse 02-14-2011 06:28 PM

Thank you for that link. My '88 is built on an '87 P30 chassis so that manual will come in very handy. I had downloaded a manual from the Workhorse site with some useful information but so much has changed in the 24 years it is only useful as a guideline. This is perfect!

8rmesse 02-15-2011 10:13 AM

Thanks for all the warm welcomes. I am loving my Airstream and this site has a wealth of information. I visit it on nearly a daily basis, sometimes to research, other times just to read random threads. Keyair, the canister I am speaking of is in the right hand wheel well, not the doghouse. The empty fitting measures 1 3/4, the fitting next to it that does have a hose attached runs to one of two air pumps (the one on the lower front portion of the engine) I'm all but positive it it is an emissions related component, just not sure if anything is supposed to be connected to that fitting or not. The fact that is is barbed (or flared) on the end sure makes me think it should have a hose or something clamped on it. Thanks again for helping.

Oh yeah, I went through the chassis manual 3 times and didn't find a picture that accurately represented the canister in question. It may be in there but there aren't any pictures that look close enough to it to know that it is what I am looking at... Great manual though, I am lucky to have it.

Keyair 02-16-2011 01:05 PM

Ok, glad that helped a little!
I spent a day or two downloading and saving them to my computer, but I found its easier to and then printing everything I could find, and now I have 2 full thick ring binders with it all divided into sections!
Here is what I have:
AS Owners Manual.
AS Service Manual
Chassis service Manual
Kohler Genset Manuals(Service, parts, and instalation)
A&E Awning Manual
Also I downloaded and printed a bunch of other stuff that is useful.

So yours has the twin air pumps?
With the engine running, you say you can feel suction there?
Interesting....

Keyair 02-16-2011 01:42 PM

Delving into my collection of manuals and the like I found something...

In my 1984 Chevy manual I saw a mention of a "Secondary Air Injection Pump Silencer"

A Search online took me to Wikipedia, and here is a paragraph from that site..
The interesting comment is the very last line...

Pumped air injection
Pumped air injection systems use a vane pump turned by the engine via a belt. The pump's air intake is centrifugally filtered by a rotating screen to exclude dirt particles large enough to damage the system. Air is delivered under pressure to the injection point(s). A check valve prevents exhaust forcing its way back through the air injection system, which would damage the pump and other components.
Carbureted engines' exhaust raw fuel content tends to spike when the driver suddenly releases the throttle. To prevent the startling and potentially damaging effects of the explosive combustion of this raw fuel, a diverter valve is used. This valve senses the sharp increase in intake manifold vacuum resulting from the sudden closure of the throttle, and diverts the air pump's outlet to atmosphere. Usually this diverted air is routed to the engine air cleaner or to a separate silencer to muffle objectionable pump noise.

8rmesse 02-16-2011 06:32 PM

That's probably what it is an intake muffler for the air pump. Yes, I feel quite a bit of suction at idle but since it is attached to an air pump that makes sense. I still wonder if there should be a filter attached to the fitting though.... I have all the owners manuals that came with the Airstream new, even the bill of sale and options list. I have manuals for everything including the Airstream manual, the Chevrolet manuals, the manual for the Kwikee electric steps, the cruise control the hydraulic levelers even the microwave, Emerson Insta-Hot water heater and so on. The manuals even show how to install and troubleshoot most of the items. The original owber saved everything and I am glad. They also saved all the receipts for service and repair work as well. So the chassis manual was a welcome addition to my paperwork although I'll probably never print it out. I don't mind referencing it on my laptop which is always in the motorhome with me. If someone has an '87-88 and can look up in the rear upper corner of the front right hand wheel well to see if anything is attached to that fitting on their unit my mystery will be solved, I guess it's just bad timing since a lot of units are in storage right now... I appreciate all of your help though.

Keyair 02-16-2011 06:35 PM

If that is what it is, I would think that there should be no suction....
From what I read and posted it is an vent out item, not suction.
Is yours a TBI motor?

8rmesse 02-17-2011 04:47 AM

It is a carbureted engine. I am pretty sure the open port is where the air pump is drawing it's air from (it has to intake the air from some place) still I am left wondering is there should be a hose or something attached to it. After all, why is it a barbed fitting if there isn't supposed to be a hose and clamp attached? Of course the answer could be as simple as "because that's the way they made it" but it really has me perplexed. I am less worried now that I know that the suction is coming from an engine mounted pump and not the carburetor intake but I still would be much more comfortable driving the ol' girl if I knew that everything was hooked up the way GM intended it to be. Honestly all this eighties technology emissions equipment is just a jumbled up nightmare. In my younger days I would probably be ripping it all off just as fast as I possibly could but even though emissions tests are only performed on 1996 and up vehicles (when the mandatory switch to OBD-2 was made) in my county ('87-'95 is just a visual inspection to check that all equipment is still installed and nobody EVER does it) I will leave it in place. It would probably run better stripped of all that crap though. I'm certain not spinning two air pumps would free up some horsepower, still it is going to stay. I'm sure it would hurt the resale value to remove it and someday the government might require emissions testing even on older vehicles if for no reason but to force vehicles off the road (much like California). Thanks again for all your help. You seem to be as interested in solving this mystery as myself now. Don't lose any sleep over it though. Somewhere there is a person who can just bend down, look in their wheel well and tell me if there is supposed to be a hose attached to that fitting or not, LOL :o) Thanks again for all your efforts.

John H. 02-17-2011 07:36 AM

If the Hole in the canister is for Air Intake ?

Maybe a Hose, say 18 inches Long would keep some road grunge from interring the canister.

water could enter, then drip out with out entering the canister

8rmesse 02-20-2011 05:56 PM

Quote:

Originally Posted by John Haggard (Post 952961)
If the Hole in the canister is for Air Intake ?

Maybe a Hose, say 18 inches Long would keep some road grunge from interring the canister.

water could enter, then drip out with out entering the canister

Thank you and while this might be a good idea, it does not answer my original question of is there supposed to be something connected to this fitting. Does anyone out there have this same device on their motorhome? If so could you please check yours and let me know if there is anything attached to yours or not? I sure would appreciate it. I am preparing for a cross country trip and I want everything hooked up and working the way the factory intended it to be beforehand. Thanks so much for your time and efforts.

Keyair 02-20-2011 08:34 PM

If my memory serves me, the air INTO the pump is drawn in at the front of the pump between the vanes of the plastic fan thats between the belt pully and the pump body. If this canister is what my research suggests, a silencer, there should be no intake from it, only a pressure release for when the throttle is shut sharply.

8rmesse 02-23-2011 07:41 PM

If that is correct then that's all the more reason to know what if anything should be attached to the fitting, there is a lot of unfiltered air flowing into it after all. :huh: Alas what I thought would be an easily answered question remains unanswered. Please, somebody has to have this same device on their motorhome. If you get a chance take a peak. You'll be solving a mystery and helping a fellow Airstreamer. Thanks so much.

Keyair 02-24-2011 12:10 PM

If it is a silencer for venting excess pressure, there should be no suction at the fitting AT ALL. If it is what we think it might be, and you are getting suction, there is something wrong with the system. It could be as simple as a Vacuum pipe off a valve somewhere.
Do you have the OEM filter housing, with the vacuum diagram on?
I hear ya on the "no info' issue.... I had the same problem with my smog equipment saga.... Every year, every weight model seemed to be equipped different.
I had to buy a Smog Book to figure it out... and its the book that the Smog Stations use, so it should be correct!
I looked up your model year, and all it says is that is AIR equipped.

8rmesse 04-23-2011 05:54 PM

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Might as well try to revive this since spring has sprung, anyone feel like looking in their 87-88 345 motorhome front curbside wheel well and telling me if there is anything attached to the open fitting of this canister on their motorhome? It is up high towards the back of the wheel opening and attaches to an AIR pump. I know it's not an EVAP canister now or cruise control vacuum canister, I don't really care what it is at this point I just want to know if there is supposed to be anything attached to it. Thanks everyone :)


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