Petrol Tank
Sealing
From a beginners eye view
By
Rick Trivett
Right, quick introduction for those of you that
don’t know me. I am often seen tagging along on MZ runs (don’t
laugh they are a good bunch) in Devon on an aged CM400T (which
is suffering from being stood in the garden for three years).
Some of you will know me from various motorcycle forums as
Grumpy Git (previously as Moody dragons). I am a qualified bike
mechanic and CBT instructor tho have not done either for years.
I also used to instruct under the old 2 part test at Tiverton
College.
My petrol tank has seen better days, but
I managed to find a replacement tank (in the US because the 400
was never sold in the UK) on that wonderful part finder EBay.
However, our wonderful postal service managed to put a few small
dents in it (thank you parcelforce $#@$%!!!!), and the inside of
the tank has a coating of wormy rust from having been sat on a
shelf somewhere.
Whilst the dents (though annoying) are easy enough
the rusty innards need some attention so I am embarking on an
adventure to seal the tank. Several people in the MZ club have
shown an interest in this so I though I would record the events,
trials, mistakes, head-scratching and swearing for the benefit
of others who might want to try out the process.
Getting
the kit.
I am a reader of Classic and Motorcycle Mechanics,
and they have tried out various kits, so after much frantic
reading of back issues (something to do on 12hr nightshifts) I
opted to buy from Frost Auto Ltd. I bought painlessly on line
from
www.frost.co.uk or you can ring
01706 658 619 for a catalogue.
Their motorcycle tank repair kit will do up to a 4½
gallon tank. It costs £24.00 inc. VAT and £4.51 for p&p. A few
days later it duly arrived. (I also made a copy of their hints
and tips for tank sealing page from their website and if anyone
would like a copy please let me know.) The kit is comprised of
three parts, an industrial strength cleaner, a rust
remover/surface etcher, and the sealer itself.
Working 60hr weeks on nightshift, the kit has sat
opened but otherwise unmolested under my chair for several
weeks, until I could get a straight run at it instead of doing a
bit here and there. So having found myself without any work for
a couple of weeks (how am I going to pay the rent???), I have
run out of excuses not to do it, and it’s that or the housework.
And lo, with the sun rising in the west and the pre-dawn gloom
of midday approaching the task was begun. Having never done this
sort of thing before, I read the instructions that came with the
kit (again) I read the info I had pinched from their website
(again) and read the instructions on the bottles. I even read
the description in the catalogue. Great, but they all said
slightly different things. #@$£%&%%*$£!!!!!!!!! Therefore, what
follows is the distilled wisdom (or folly) of many fag breaks
and mugs of coffee.
Stage
One, cleaning the tank.
It doesn’t actually say so in the instruction until
stage two to remove the lose rust from the tank, but I
don’t see the point of cleaning the lose rust and scale so I
though I would get rid of that first. Thus, several handfuls of
gravel (an old tick but a good one) were thrust into the tank,
the holes covered, and the vigorous shaking (the start of much
shaking to come) began. I think it is an idea to point out at
this stage that many tanks (mine included) have a deep lip
around the filler hole in order to prevent spillage. This mean
the task of getting the gravel back out of the tank requires
every bit as much vigorous shaking as it does to remove the
scale from the inside. After an hour of shaking and swearing
even a small petrol tank like mine becomes very heavy.
The Marine Clean is a strong caustic alkaline to
remove the gum, varnish, and petrol residue from the tank. It
has to be mixed one to one with water and works better hot. So
with the tap outset blocked up, and having boiled the kettle,
the solution was poured into the tank and given a good slosh
around. The tank has to soak in the stuff for 24 hours, with the
stuff sloshed around frequently and the position of the tank
changed so that all of the tank gets a good soak. It is at this
point you realise how surprisingly difficult it is to prop the
tank up at weird angles. Anyway, after 24 hours this solution
was poured out of the tank into a plastic bottle because this is
reusable and can be used for degreasing other thinks. Then the
tank was swilled out with copious quantities of clean water.
This had a noticeable cleaning effect inside the tank, and made
my hands look like I’ve got leprosy. I forgot to wear gloves.
More swearing.
Serious
warning
1.
Marine Clean is a good degreaser, but please wear gloves. I used
it again for something else and forgot and now have nasty
caustic burns on my hand.
2. This stuff
also eats nickel plate. I tried to deglaze my carbs, no problems
there as long as you wipe over the aluminium with an oily rag
after to stop worming, but have ruined a pair of needle jets in
the process $%#@*&^^%$£!!!!!! So be warned.
Stage Two,
rust remover.
Metal Ready contains zinc phosphate and phosphoric
acid, nasty stuff so gloves are essential and it is advisable to
wear eye protection to ward against splashes. This stuff eats
rust, etches the tank in preparation for the sealer, and leaves
a coating of zinc phosphate on the inside of the tank to prevent
further rusting.
So looking like a perverted spaceman (oooh those
rubber gloves!) this stuff was poured in and sloshed around. All
areas must get a soaking for at least ½ an hour which means much
propping of tank at interesting angles again (remembering to don
protective gear each time).
Again, this was poured out into a non-metallic
container, as this can be re-used as well. The Metal Ready
has actually eaten all but the worst of the rust and left a grey
metallic layer of what is presumably zinc phosphate on the
inside of the tank. It does what it says on the plastic bottle!
The tank then has to be rinsed out again (more
shaking) and the inside of the tank dried. This is one think
that all my sources of information do agree on, is that it is
vital for the tank to be thoroughly dry or the sealer will not
work. They all say that leaving the tank to dry is not enough
and that moving, preferably warm, air must be used for an
extended period of time to get rid of all traces of moisture.
Stage
three, sealing the tank.
Well so much for time off, a phone call at 4pm from
boss required me to go into work at 7pm the same day. More
swearing. However, I have finally got around to this last bit.
Having made sure that the inside of the tank is
thoroughly dry and blown hot air from the hairdryer in for ages
in as many directions as possible, and blocked up the petrol tap
hole, the stuff was poured in (gloves on first as how do you
wash of something that solvents wont remove??) and the filler
hole masked off. Then lots of vigorous tank shaking and holding
it at weird angles again to make sure the stuff was
comprehensively sloshed around the inside to coat all surfaces.
Incidentally, it looks like silver hammerite in the tin.
The tank was then left for half an hour. At this
point I deviated from the given instructions and sloshed the
stuff around again for good measure. Wait another half hour, and
pull out bung from petrol tap hole to drain off excess. (It is
worth noting that this stage can be repeated to build up a
thicker coat but by then my arms were six inches longer and
threatening to drop off.) Again the tank has to be held at
various angles to drain as much as possible off so that it does
not pool anywhere.
Next the easy bit, pull off masking tape from
filler hole and leave to cure for 4 days. Fine no problem there
me thinks. Wrong. Being a single gent again I had done all this
somewhere convenient and above all dry, i.e. the kitchen. By
heck that stuff stinks. Oh, not when you open the tin, or even
when you slosh it around, just when it is curing. So let this be
a warning to bikers of either sex who have partners and try
this, make sure they have gone away for a week before you do it
J.
The end result after curing is a thin, slightly
glittery, plastic coating all over the inside of the petrol
tank. So for want of a better cliché it does what it says on the
tin.
Ride safe, ride free,
Rick
rickgrumpygit@hotmail.com
