Plastic Welding a Gas Tank
I am going to repair the gas tank from a 1970 Ski Doo Nordic here.
When plastic welding, the first thing that must be done is to identify the plastic.
This tank is PE or Polyethylene.
Polyethylene has the following characteristics, Semiflexible, melts & smears when grinding, usually semi-translucent.
Polyethylene is generally used on the following types of products, Overflow tanks, inner fender panels, valences, interior trim panels, RV water storage tanks, gas tanks.
Please note: Think safe. remove all gas, and flush. Let it air dry out. If you can smell gas, do not apply heat to it.
This is as it was pulled out of the snowmobile. Note the cracks by the filler neck area, and also that the filler neck is broken off.
This tank is probably not the best candidate to fix, but hey if we can do this one, we can do any of them!
The Urethane Supply company welder that I use.
More of the damage
Close up of some of the damage. Note how fractured it is.
Tank cleaned up and ready to start.
I applied a heat lamp to aid in getting the plastic back in place as it had bulged out considerably.
Shows how the cracks are "v'd" out. This is a must along with cleaning. I used carb cleaner and plastic cleaner.
Starting to weld up. I did the side first, this helped me to get the filler neck opening to fit better.
Shows the top ready to reapply the filler neck.
Beveled or V'd both pieces.
Used tape to hold it in place so that I could tack weld it in the proper location.
Before using any plastic rod to fill, I ran around the entire neck and welded using only the original plastic from the tank.
The neck finished welded with rod.
The tank welded up.
The welds smoothed out with a grinder. I finished off a few low spots better.
view of the filler neck.
Used 150 grit on a DA to finish this off and smooth some of the spots out.
I applied about 4 pounds of air pressure to the tank to verify that it will hold. Do not use high pressure, or you will blow out all of the seams.
Now I can get back to sledding!