Trunkseal and Fuel Filler Compartment Drain (1800) Notes

First Published Jan2020, R. Kwas, updates on-going

Fuel Filler Compartment 1800 Drain



The svelte body and design of the 1800, does bring with it some special drainage issues...the clean rear bodywork has no vertical seams for water drainage.  Water collecting in the depression where trunkseal is located, as well as water collecting in the Fuel Filler Compartment 1800 Drain both need a way to escape, or else it will remain in a puddle, and grow mold, small water foliage, possibly primordial forms of life, but this is a sure recipe for rust.

Trunkseal Drainage: 

It seems there are variation of drain holes punched with fittings and drainhoses fitted and also no drain holes punched, but no drain hoses fitted from the factory...I am trying to compile the experience of owners of the various production years, to establish a correlation. 

Some of the subsequent pictures were supplied by V. Koskinen of the Finnish 1800 Club, and used with his kind permission.

Factory Drainage Provision:  

Trunk Lip of two (Green) present on Vesa '61 1800, when the British suppliers of the chassis were still on their best behavior as a subcontractors of Volvo.  See also P1800 chassis history

Drain openings (2) are typically obscured by the Trunk-gasket and so not immediately obvious (especially if no fitting or hose was installed below to further give away the location (like also on my '66!), but if present, they will be apparent at approx the lowest points on either side...look for a half-moon or 3/4" arc punched into the sheetmetal and only slightly deformed to present a drainage slot (it might be painted shut too).

Since my Trunkseal depression drain hoses were also not installed (no hose fittings in sight!), I made some copper hose-fittings and riveted them into place, below the Drainslots. 


Onto these, I installed 3/8* ID clear tubing to tie them into the Fuel-filler Depression drain-hose (thankfully present)!  I don't know why the factory never installed the drains on some later cars...maybe the Brits were already cutting corners in ~'65 or so, on their way to working themselves into bankruptcy...  The chassis of my '66 was still being supplied to Volvo by Jensen/Pressed Steel Cowley, but shortly after that, the contract was cancelled by Volvo, and production was moved to the Torslanda plant back in Sweden. See also: P1800 Chassis History

Drains can be added (or retrofitted if not present) to the seal surface, using the punched drain openings, and plumbing them to the existing Fuel Filler Compartment Drain tube.  J. Massey added some fittings and hose, and tied the drainage into the Fuel Filler Compartment Drainhose under Fuel Filler Compartment...a good solution, as simply allowing drainage to the panel below is asking for rust in the outer panel of the apron (see below!)...there are drainholes, but water would have to find its way to them (and not be captured by any sand there...a very BAAAD situation!

Pictures of J. Massey's drainage solution and used with his kind permission. 

Result of Lack of Drainage Provision:

View of inner panel, looking from under trunk, rearward (Tank removed, and round Tank corner of opening is visible).  To help with viewer's orientation, Trunk latch is white rectangular box in upper area of shot.  Water which is simply allowed to run down slot between outer body and Trunkfloor, is then in the space between the inner and outer panel...sure there are drainholes (Yellow), but water will be captured by any sand present in that narrow space and promote rust on both panels as apparent here!.  Pictures by Jean of the Volvoniacs Forum and International P1800 Owners Club ( ), and used with his kind permission.   

View from below and in back of the vehicle.  (Tank removed, Tank opening is visible)...result of moisture (likely wet sand between inner and outer panels)  is clearly visible. 


Fuel Filler Compartment 1800 (Carburetted) Drain:  

A Drainage provision was included for water entering the Fuel-filler Depression.

View of Fuel Filler Compartment with its Drainhose (Green) connected and routed through the Trunk-floor to the outside.
Also evident is the Fuel Tank Vent (Orange), which has a very different function.

Water in the Tank: 

It is crucial to keep the small drain opening in the Fuel Filler Compartment, free of debris which can block it, which would allow water to build up to a level high enough to flow into the Fuel-fill pipe!  That would be a failed attempt at water injection, and generally BAAAAD!  Check for and clear any debris at each fill-up! It doesn't take much to block the tiny drainhole! 

Vesa's nicely restored Fuel Filler Compartment.  Drain is below locking tab, location is shown in OrangeKeep this Drain Clean and Clear!

Why do Fuel tanks fill with rainwater?  Unfortunately, the Fill-pipe edge is lower than the Body overflow edge, so if normal path for drainage A  is blocked, and spring-loaded rubber seal on Fill-pipe opening is less than perfect, secondary drainge path B  is into Tank!!  This implementation having originated from a country known for rain...hmmm.

I don't know much, but I know water likes to run downhill...




Spedeswede thread: International P1800 Owner's Club 


Reference Information: 

P1800 Chassis History according to Vesa:  "Assembly was moved from Jensen factory, West Bromwich to Sweden already at the beginning of 63. Only 6000 first ones were so called "Jensens". (1800S; S stands for Sweden made). Body parts kept coming from Scotland to Sweden though. (Pressed Steel Cowley)".


External material sources are attributed.  Otherwise, this article is Copyright © 2020.  Ronald Kwas.   The term Volvo is used for reference only.  I have no affiliation with this company other than to try to keep its products working for me, help other enthusiasts do the same, and also present my highly opinionated results of the use of their products here.  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! 

You are welcome to use the information here in good health, and for your own non-commercial purposes, but if you reprint or otherwise republish this article, you must give credit to the author or link back to the SwEm site as the source.  If you donít, youíre just a lazy, scum sucking plagiarist, and the Boston Globe wants you!  As always, if you can supply corrections, or additional objective information or experience, I will always consider it, and consider working it into the next revision of this article...along with likely the unique metaphor and probably (likely) wise-a** comment. 


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