Fuel Tank Breather

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Boggie
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Fuel Tank Breather

Post by Boggie »

Evening All,

As well as the inline fuel pump and filter I intend to replace all the fuel pipes and hoses. I have just ordered the feed and return pipes, as well as suitable hoses/clips etc but I would like to replace the tank breather system too. However, looking at RealOEM I am struggling to work out what is where and what to order. I had a look underneath the car and under the access panel in the boot; it appears the feed and return pipes attach directly to the lift pump flange but I can see no sign of a breather system. Can anyone tell me where to look please?

Cheers,
Ian

P.S: After 15 years, laid-up in a barn and one year of tinkering in my workshop, the Shark passed its MOT test on Saturday! Thanks to you all for helping me get there.
1985 M635CSI
Classic Car and Bike Collector & Restorer.
baders
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Re: Fuel Tank Breather

Post by baders »

Into the boot and look up :)
1986 635csi LOCUTUS / Arktis Blau Metallic / Pearl Beige / S38B36/ Close ratio dogleg 5sp
2002 E46 M3 / Topaz Blau Metallic / Black Nappa / 6 speed SMG software tuned / Bilstein PSS10 Coilovers / CMP RACP reinforcement
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jps635
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Re: Fuel Tank Breather

Post by jps635 »

......underneath the trim cover.

There is a plastic expansion tank with 4 hoses connected. 3 are vents from the fuel tank filler neck (under/below the rubber flap), and the 4th connects to a fixed line that should/may run too a charcoal canister up front. From memory I ordered about 4m of 11mm hose but didn't need all this. Is a bit fiddly but otherwise straight forward. Just be careful removing the hoses from the expansion tank nipples as they/re very easily broken.
'85 635csi JPS (RA2-66)
bpoliakoff
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Re: Fuel Tank Breather

Post by bpoliakoff »

I put my 81 euro with Motronic back to Euro spec meaning removal of federalization and venting the gas tank. If that's what you are after, I removed the charcoal canister to begin with. From there, you can go to realoem and under that year car and under euro go to fuel supply, ventilation section , then diagram expansion tank tubing and if you look at items 8 and 12 you will see the main parts needed to vent the tank as original and the parts are still available. The vent tube IIRC runs along the right side of the trunk across the back lip and exists on the left side of the license plate panel. The end of that pipe has a little trumpet on end on it and is totally neat looking. As you will see the parts are totally inexpensive.
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
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Boggie
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Re: Fuel Tank Breather

Post by Boggie »

Thanks Chaps,

Sorry, I should have said - my car is a RHD European (UK) spec. So, no charcoal canisters etc. :)
Parts 8 and and 12 look like the ticket, thanks. Where is the expansion tank and how much 11mm tubing will I need to replace the 3x pipes (which I assume hook up to the tank?). I want to replace the lot.

Cheers!
Ian
1985 M635CSI
Classic Car and Bike Collector & Restorer.
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Re: Fuel Tank Breather

Post by bpoliakoff »

Look on realoem it tells you. I am not sure what it is telling you though it says 6X11mm So it is 6X what? Go to your local auto parts store and buy several meters of 11mm fuel hose if it's just vent hose. If feed hose than make sure it's fuel injection hose. Ian learn to use realoem it will save you a lot of time and answer many of your questions as well.
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
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Boggie
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Re: Fuel Tank Breather

Post by Boggie »

Thanks for the fast response. Agreed, RealOEM is a great resource and I have used it extensively throughout the last year during the restoration of my barn-find M635CSI. If only there were such a site for all the other cars I have restored, life would have been much simpler.

However, the problem with RealOEM is that it is, as I am sure you realise, just as parts catalogue. So whilst it does provide part numbers and drawings, it doesn't necessarily show location or specifications. Hence my original question above, looking for help from anyone with experience of replacing the tank breather system, on length of pipes, location/routing etc.

Thanks,
Ian
1985 M635CSI
Classic Car and Bike Collector & Restorer.
bpoliakoff
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Re: Fuel Tank Breather

Post by bpoliakoff »

When you buy #s 8 & 12 they will lay out only one way and show you how they route. As to the hoses, as JPS said, 4 meters is more than plenty to replace all of the fuel lines and vent hoses., Just make sure you buy hose rated for fuel injection that way you can use the same hose for feed and vent lines.
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.
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