Restoring and coating fuel tanks is a routine service here at the shop. Given that we take on so many restoration projects, reviving tanks is a necessary skill to complete our work. We often get asked questions surrounding best practices for restoring tanks, what products we use, and when someone should (or should not) DIY the job. In this month’s newsletter we will detail our process for revitalizing the inside of your gas tank along with some tips and tricks we have learned to help save you time, money, and headaches.
WHEN IS IT NECESSARY?
First, let’s discuss when coating your tank is necessary. The inside of fuel tanks consist of bare metal and wherever there is bare steel, there is an opportunity for rust to develop. This is problematic because rust in the fuel tank can travel and create a hazard for your carburetors, petcock, and/or fuel pump, potentially leading to costly repairs down the road. Although we most commonly perform the coating process on old rusty tanks, it can be done on new tanks as well. In general, it is not recommend for all new tanks. However, it might make sense for a motorcycle that is stored most of the time. Motorcycles that are frequently ridden are not as susceptible to tank rust for a couple reasons:
| ▪ | What’s under gas wont rust. This is why we recommend storing your motorcycle with the fuel tank “tippy top” full. |
| ▪ | Frequent use makes it less likely for condensation to form. This moisture on the inside of your tank is what creates rust. |
When we receive in a rusty fuel tank we always begin by assessing the extent of the rust. We are looking for pinholes or spots in the tank where the rust has made the tank wall too thin for us to work with. The coating will fill some surface pinholes, but is not appropriate for cases where there are numerous or large holes. The only options in those cases is to cut the damaged parts out and weld new metal patches. Unfortunately, this process also requires repainting. In some cases, replacing the tank is more cost-effective when paint work is required.
ACID AND ALCOHOL
Once we are confident we have a tank we can work with, we fill it with distilled white vinegar. Why white vinegar? It’s readily available, extremely affordable, and to put it plainly, it works. The acetic acid in white vinegar will dissolve the rust. For mild cases, we let it sit overnight and for more severe cases we let it sit for several nights. We also sometimes use a tumbler and spin the tank for hours, adding drywall screws inside to help loosen and breakup the rust.
TIP: A magnet is of great help to remove the screws once the tank has been tumbled!
We cannot stress enough how important it is to achieve an entirely rust-free and clear surface. The coating will not adhere if surface prep is not done diligently!
Next, we discard the vinegar and flush the tank thoroughly with clean water. At this point, it’s important to work quickly to ensure new surface rust doesn’t form. We add half of a quart of rubbing alcohol, shake it around, and then dump it out. We then repeat the same process with the remaining half quart of rubbing alcohol. This will displace the water and quickly evaporate, leaving us with a completely dry surface with the help of an air hose. At this point we remove the petcock and gas cap.
RED-KOTE OR BUST
With a rust-free and dry surface, we now coat the inside with a product called Red-Kote. We’ve tried other products over the years, including Kreem Coat, but have only been impressed by Red-Kote’s adherence and longevity. The tank needs set on some sort of stand that allows the can of Red-Kote to sit underneath where the petcock was removed. This is to allow excess product to funnel back into the container for later use. Plug any holes (petcock, fuel sending unit, etc.) with rubber plugs, corks, or masking tape. Pour enough Red-Kote to coat the entire tank, reinstall the gas cap and rotate the tank to ensure even and complete coverage. We’ve found that most tanks require about half of a quart, but it’s ok to use a little more since we will drain excess product at the end of this process. At this point we remove the plug from where the petcock would mount and set the tank on the stand above the can of Red-Kote. After letting any excess product drain, allow the tank to completely dry.
TIP: Dain once tried to catch the excess product with styrofoam and learned that Red-Kote will eat right through it, resulting in a huge mess. Draining the product back into the can helps eliminate waste but also provides a safe place to store it.
After the tank has dried, replace any parts that were removed and reinstall the tank back on the motorcycle. This is a long-term solution that will prevent rust from returning for many, many years to come!
RESERVE TANK RESERVATIONS
While on the topic of tanks, a common question we get, particularly from new riders, is how to fill the reserve tank.
It’s a bit of a trick question because there really isn’t a ‘reserve tank’ at all. Rather, there is a separate, shorter fuel line within your gas tank that your petcock utilizes when switched to ‘reserve’. To have access to that reserve, you just simply fill your fuel tank.
Check out the image below for a visual breakdown of how this works:
