Rust in fuel tank

[RVsteve]

I drive a 2008 40' Holiday Rambler diesel pusher with about 24,000 miles. Recently, I had a fuel leak around the weld on the bottom drain plug. The service facilty drained and removed the tank. The tank repair people had to clean the interior of the tank before welding. They said there was quite a bit of rust on the walls of the tank, which they removed. There was also rust on the top of the filler tubes which I assume was caused by condensation.

Here's the mystery:

1. I try to only fillup at large, busy truck stops.
2. I always fillup the tank before storing.
3. I check the primary filter for water at every fillup and find little, if any, water.

So, what is the source of this water in my tank? Is there an additive that would remove the water? Would it help if I left the cap off the filler tubes to allow moisture vapor to escape while in storage? Any other ideas? I don't want to be forced to replace my tank in the future.


Thanks,
RVsteve in San Diego

[Barlow46]

You are talking about rust on the outside of the tank, correct? This is a way out in left field guess but it is possible your tank was stored outside before it was installed. Due to the slowed economy, perhaps there was a surplus of tanks and yours gathered some rust. The other possibility is the area of the country you live and store your coach in. Salt air can have some effect but I'm bettin' on the "stockpile" theory since yours is a 2008.

[Barlow46]

Oops...just re-read the Title of your post. "Rust IN fuel tank". I guess it is still possible that the tank was stored empty outside for a period of time. Diesel fuel is "oily" and as long as it is splashing around in a tank that new, I don't see how rust started unless it was stored empty, which you indicated that you never do.