Fuel Tank Notes   
2021 R. Kwas   [Comments Added]

Fuel Tank Configurations
122 Sedan Tank
122 Station Wagon
    122 Wagon Fuel Cap is non-vented
1800 Tank
1800E Tank
    Pick-up Tube and Anti-Slosh Compartment

1800ES Tank

Common Fuel Tank Issues

Gas Caps

Derusting Tank

Reference Information



Fuel Tank Configurations: 

122 Sedan Tank:

The Volvo Fuel Tank configured for use in an Amazon.  Notice the arch clearance on left...this is a strong suggestion that the same tank pressings were also used for the 1800, where the vent fitting visible in the 1800 Tank picture, is located there (filler pipe enters Tank below seam).  


122 Station Wagon Tank is somewhat unique, and shallow, and it looks like the (side) filler pipe is shorter than on the sedan...this could be the explanation why there is typically a fuel stain under the Fuel Filler of Kombis (and it is important to assure the Fuel Cap has a good seal to prevent this leakage and resulting staining). 

The important difference to note in Sedans vs. Kombis:  Fuel Cap on the Kombis are unvented to prevent spillage (there is a vent in the filler tube!), unlike the vented Fuel Cap of Sedans.     

Picture Source:  https://vp-autoparts.se/sv/artiklar/bensintank-amazon-220-kombi.html

122 Wagon Fuel Cap is non-vented! 

My posting to thread:  Rebuild Gas Cap  https://www.swedespeed.com/threads/rebuild-gas-cap.640073/#post-7772390

"Wagons never had locking caps, so I deduce this is an aftermarket one which a PO or you have installed...and knowing it's an aftermarket one, I also deduce that it is vented, which they typically are...and herein lies the rub, this does not play well with the relatively flat Tank and Filler, and is likely cause of your leakage! Factory wagon Fuel Caps were not vented...that is not to say Kombi Tanks were not vented...they were!...but in the filler neck and occurring behind the Cap (which must do its intended function without making a mess). I suggest your leakage is from the vented Cap which you could address. I would suggest rebuilding it, and while you have it apart, you will undoubtedly see the venting provision, which you should defeat before reassembly. Please take and post pix of Cap rebuilding!

Naturally, the sealing of the rubber gasket between Cap and Filler is important and must function well. You may need to adjust or replace with thicker to assure sufficient preload.

From the Exploded Assembly Diagrams at GCP.se site:

Tank venting is routed from Fuel Filler, behind interior panel, not by way of a vented Fuel Cap! 


1800 Tank:

1800S Tank, with Filler entering the Tank below seam and just above it the Vent connection.  Note area for 122 Filler location.


1800E Tank:

Pick-up Tube and Anti-Slosh Compartment  

Picture of the inside of a tank from an injected 1800, showing Anti-slosh compartment with fuel pick-up.  Second picture shows fuel return from Fuel Pressure Regulator of the Bosch D-Jetronic Injection System.  Two big general tank baffles are also apparent.

Source of (2) pictures:  http://www.gas-tank.com/Links2009/Volvo.htm


Internal anti-slosh compartment.  Fuel return has been reinstalled, and it also feeds into anti-slosh compartment.  Notice at Green, Fuel Pick-up tube enters the chamber at the very bottom, as well as the very small fill-holes next to the tube which allow replenishing the anti-slosh compartment from the main Tank volume.  


1800ES Tank with in-tank Prefilter (1973 only? to be confirmed!)

The following four pictures and info for 1800ES tank were kindly supplied by Jim Perry: 

'73 ES Tank topview, visible is the Senderhole.


Same Tank bottom view, showing both the central Drain, and the Sump with Prefilter location.


Prefilter can be simply pulled from Feedtube, after removal of Sumpplug.  Any particles of contamination which have been sucked onto Prefilter fall into the sump when suction from the pump is no longer present, so will be inspectable after removal of Sumpplug.


Note the difference both in the threading and tool necessary for installation/removal in the OE brass Sumpplug, and those of replacement Tanks. 


Common Fuel Tank Issues:  

Solder Joint failures on 122 Sedan Tank:

Screenshot from Pieter Beeckx video used with his kind permission :

Common weakness of the 122 sedan Fuel Tank.  Soldered joint at Filler Neck to Tank.  The solder fractures due to weight of the fuel filler pistol being hung onto the filler.  This is less of an issue in other models, where the filler is better supported in the body. A leak-test with water verifies the fractured solder joint at Filler Neck root. 

My comments to a Faceplant post. 

" Leakage as shown in Pieter's video is absolutely typical...and due to cumulative fatigue of years flexing the joint from hanging the fuel-filling pistol onto the fuel filler...that is only a solder joint, and it gets stressed and shows once again, that solder just isn't mechanically strong and up to the task long-term...  My Tank had a cracked solder joint there also (although I was not particularly rough with hanging the fuel filler on there!)...I resoldered it, but noting the long-term weakness, added strengthening gussets (see below) to significantly improve the mechanical support of the filler-neck.

If you cannot solder (for which tank must be COMPLETELY empty and vented, or baked in the sun until no more strong fuel smell confirms non-flammability!), OR you don't want to remove Tank, you can temporarily seal fuel leaks with fuel compatible (silicon) RTV (like Dow-Corning 730 Fluorosilicon formulation, NOT 732 general purpose [which is not hydrocarbon compatible!]) ...until it can be repaired right...but again, I highly recommend installing strengthening gussets to support filler neck or this condition can easily return!  There's not a lot of room, but enough...see below for a sketch of what I installed last time my Tank was out.  "


Rick Watson Picture used with his kind permission.  


Answer to Faceplant request for details on gussets I mentioned.

"Sorry no pix, I did this long ago, but I remember the design well...2 gussets had to be fairly small to clear the bulkhead Fuel Filler passes through, plus the trunk [floor] rises back up, so it must clear that also...here is a conceptual sketch which captures it well...I used ~20ga sheetmetal and soldered it into place [2 are added!]. Cheers
Edit: It was tight getting the tank with gussets back in place, so I suggest you make some trial gussets of cardboard, tape them onto Filler and trial fit Tank back into place to assure they don't foul on the bulkhead during installation...there's not a lot of room!...only when you're happy with installation clearance, you can make it of metal and more permanent...other option of course is to cut clearance into the bulkhead, but I didn't feel it was necessary..." 


Gussets support Filler Neck to seam, here.  The fuel filler protrudes through inner bulkhead, then outer body.  No supporting rubber surround is present yet in this excerpt of the R. Watson photo.   


Gas Caps:

From Thread:  http://www.networksvolvoniacs.org/index.php/Spezial:AWCforum/st/id6591/Vacuum_im_Tank.html

Locking Cap partially disassembled, showing what certainly looks like a possible vent. 
Picture credit:  Rainer of the Volvoniacs Forum.


Derusting Tank in preparation for internal sealing

If you are going to DIY...

Internal Tank cleaning of rust...strapping the tank to a cement mixer, with a few of handfuls of course stones for abrasive. 

When using tank sealers, like POR15 subsequently, its critical to follow the sealer manufacturer's instructions to the letter...take no short-cuts, make no "judgment calls"! 

Peter Bellinck photo...used with his kind permission!   

Maybe unique, "rustic", and noisy, so should definitely be done "behind the barn", but a very effective way of prepping the Tank interior for sealing.  


Reference Information: 

Update:  Notes on a conversation with Joseph Moyer, long-time owner/operator of Moyer Fuel Tank Renu (http://www.gas-tank.com ).  They bake out each Tank and prep by blasting, to give their baked-on internal plastic coating the best adhesion possible, and their work is guaranteed for life.  They are located near Pittsburgh PA.  Mr. Moyer tells me that the Fuel Filler behind the license plate of seventies GMs was similarly susceptible to fractures on the soldered-on filler pipe (soldering is apparently the typical manner in which fittings and pipes were connected to steel fuel tanks in the past.  He has also reinforced such weaknesses with gussets [I guess great minds do think alike!...just saying!]

Knowing the internal condition of my 1800ES Tank, I intend to use their service when the ES gets next recommissioned...instead of changing to a new, but chinashit replacement Tank, guaranteed to last from 11 'til noon!...and he tells me the mounting holes of chinashit tanks often don't line up!...more of china's finest work!   Watch this space for results of the experience!


From a conversation with Don Thibault (www.p1800.com ) : 

He stocks OE Tanks and just replaces them now..."they're all going on 50 years old now..." ...he's got a valid point there! 



Fuel Gauge Information and Notes


External material sources are attributed.  Thanks again to all contributors of pictures and information!  Otherwise, this article is Copyright © 2020-2021.  Ronald Kwas.   The terms Volvo, and name of any other companies or individuals included here are used for reference only.  I have no affiliation with any of these companies other than to try to keep their products working for me, help other enthusiasts do the same, and also present my highly opinionated results of the use of their products here [like the fact that china got it wrong again!].  The information presented comes from my own experience and carefully considered opinion, and can be used (or not!), or ridiculed and laughed at, or worshipped, at the readers discretion.  As with any recipe, your results may vary, and you are, and will always be, in charge of your own knuckles and future! 

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