Re: [T3] gas tank coating?

[Jim Adney <jadney@vwtype3.org>]

On 30 May 2007 at 7:39, matthewNstanfield wrote:

> i have a 1979 Piaggio Vespa Ciao MOped. it has been highly  
> recommended that i use a product called "Kream" or "POR-15" to line  
> the gas tank to prevent rust from forming on the inside.

There's significant disagreement on these things. Personally, my experience is 
that gas tanks really don't rust inside unless they are left empty or allowed 
to accumulate water in them.

I have 2 objections to the concept of coating a tank like this. The first is 
that it is VERY difficult/impossible to control the coating application since 
you really can't see what you're doing. As with paint, a coating too thick can 
cause as much of a problem as a coating too thin, and a little pinhole in just 
the wrong place can actually accelerate rust-thru.

My second objection to this stuff is that it can/will block off small passages 
and openings that exist in some tanks and that are essential for them to work 
correctly. This may not be a problem in your Vespa, but it IS a problem in the 
FI type 3 tank.

> my question is: would this be something that would be useful on my  
> fastback as well? the tank has not had fuel in it for ten years, so  
> now would probably be the best time to do something like this if i am  
> going to.

I would say no; don't use it. There are small, essential passages in your FI 
tank. This coating will block them and you won't be happy with the result.

> does anyone have experience with these products or some advice about  
> whether or not to use them?

I've not used any of these products. I've never NEEDED one of these products. 
If you keep the tank either full, or dry, they actually don't tend to rust 
inside.

One of the main problems in the FI gas tanks is the overflow hose, which is a 
NLA part, which requires periodic replacement. When you drive in the rain with 
a cracked overflow hose, water gets into the tank. This can cause lots of 
expensive problems. I've been working on a long term solution to this, but 
don't have it yet. If anyone out there knows of a supplier of nitrile single-
hole rubber stoppers, I'd like to hear about it. This problem is not going to 
go away on its own.  

-- 
Jim Adney
jadney@vwtype3.org
Madison, WI USA

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