Fuel Tank Prep & Coating due to Rust.

[Cat Cracker]

Sooo, unexpectedly I am about to embark on cleaning my '85 FJ1100 gas tank.

I am doing this based on the condition of my carbs, as reported by Randy at RPM. Which is a pretty ugly pre cleaning report after breakdown of my carbs.
A very detailed report I must say. Kudos to RPM. I knew I was making the right decision shipping them to the experts. Despite being the recipient of
"The Worst Carbs Sent To RPM For Cleaning" award so far this year, I am humbled !

I have read a lot of the reviews, comments & suggestions here & will be putting a detailed procedure together for me to follow. That's because I forget stuff. Some interesting ideas, from turning the tank into a battery utilizing mild electrolyte allowing an anode to gather rust to good suggestions on experiences with different kits currently on the market.
Thank you all for your reports on this topic!
Breaking it down to what I perceive as  the three obvious groups. Prep, treatment & coatings.

PREP:
Remove gasoline, pull petcock, Water flush, protect external paint & gas cap.
Use of my newly acquired Harbor Freight Color Borescope ($59) for inspection.

TREATMENT:
Mechanical use of chain, bolts etc. to release pieces of rust chips.
Chemical use to attack surface rust & contaminants. Use of all  required PPE.
Repeat as necessary,  up to 4X or whatever is necessary. Thanks Randy.
Borescope again'
Thorough flush & drying

COATING:
Choice coating based on research of previous users experience. I have chosen the KBS coatings based on good reports from users here.
Application based on prior users experience with volume & tank rotation applications, volumes used for the '85 FJ tank, specifically to avoid pooling and application to every corner & crevice in the tank.

Based on my first pass, my only concern is ,
1. Causing a leak with use of chains etc. during mechanical prep & chemical cleaning. If this occurs, its a replacement tank.

I plan on getting at it when ambient temp allows for quality coating application or my current wife allows me use of the mud room during the curing process.....


Thanks to this incredibly valuable resource and its contributors over the years. It is a goldmine. I welcome any suggestions !

PEACE & LOVE

[Motofun]

Also look into Caswell for an internal coating.  I've used it twice and swear by it.  I poured the excess out onto the gravel driveway 2 years ago....it's still there and impervious to rain, snow, plowing......

[Pat Conlon]

......Application based on prior users experience with volume & tank rotation applications, volumes used for the '85 FJ tank, specifically to avoid pooling and application to every corner & crevice in the tank.

You are going to have excess coating....plan on it.
Several years ago, our forum long timer David Raforth, made a suggestion on how to address the pooling of the excess coating.
After coating all the interior surfaces, turn the tank upside down and slightly tilted forward...any of the excess coating will then pool on the top front corner of the tank, leaving your petcock and fuel level sender areas free of any pooled excess coating.

Why not use the electrolysis method of rust removal?
It seems to me that it would do a more complete job of rust removal.

[Waiex191]

I used a cement mixer to clean out the tank on my Harley*.  Filled the tank partway with sharp marble chips, mounted the tank to the mixer, and let it tumble.  I tipped the mixer a few different ways to change the pattern.  Made a racket and the tank came out good.  I then sealed it with Kreem.  It is still good.

I also had a pinhole leak in my FJ tank, on the left side "corner" just forward & below of where your knee rests.  I did not have to go to the cement mixer for that as the bike was pretty new and not rusty - though maybe in that one spot.  I always figured water rested there when it was on the kickstand.

When my kid helped his buddy with his CB750A project, I no longer had the cement mixer so we rigged this up:
https://youtu.be/StGojklc1Rg



*It is a 1971 Harley Model D gas golf cart.  I've not gone to the dark side.

[RevDeal]

......Application based on prior users experience with volume & tank rotation applications, volumes used for the '85 FJ tank, specifically to avoid pooling and application to every corner & crevice in the tank.

You are going to have excess coating....plan on it.
Several years ago, our forum long timer David Raforth, made a suggestion on how to address the pooling of the excess coating.
After coating all the interior surfaces, turn the tank upside down and slightly tilted forward...any of the excess coating will then pool on the top front corner of the tank, leaving your petcock and fuel level sender areas free of any pooled excess coating.

Why not use the electrolysis method of rust removal?
It seems to me that it would do a more complete job of rust removal.

I stand by Pat with this one; Electrolysis is the way to go. I had a nasty coating in mine that required me to use MEK (VERY NASTY STUFF). But if all I had in the tank was rust, I would totally just opt for the electrolysis method. I believe I wrote something and other people have done so too. The worst part is to worry about flash rust, but that wasn't bad as long as you quickly remove water which isn't hard. Seriously give that a look before you go the chemical route if you only have rust.

Jacob

[andyoutandabout]

Another vote for the electrolysis method. Worked great for me. I didn't coat the tank after watching an Fj member spend a morning removing flakes of tank liner from his carbs at a rally.
Some rust has returned as tank is empty and undercover, but condensation gets it a bit.
Surely with gas in it  and under normal use, the rust will stay away?

[Pat Conlon]

Andy, as we old rockers have learned....Rust Never Sleeps. Remember, gas floats on water, any condensation in your tank (typically forms on the ceiling) will drop down and pool at the low points of the tank. Also, ethanol being hygroscopic, our E10 fuel will pull moisture from the air as we painfully have learned with our carbs.

Jack, thanks for the recommendation on the Caswell Epoxy coating.
https://caswellplating.com/epoxy-gas-tank-sealer.html
I can see where the two part epoxy will have superior surface adhesion and hardness over the other coatings.
I also like the Seal Mask you can brush on your painted surfaces, so in the likely event you get some of the seal epoxy on your painted finish, you don't have to stop what you're doing and clean it off....you can proceed with the process and wait until everything dries, then wash the epoxy off the paint with soap and water.
https://caswellplating.com/caswell-seal-masktm-8-fl-oz.html

They had me in mind when they came up with this product (I'm a klutz and I know it) ....the same reason I like my DOT 5 fluid.

Cheers.  Pat

[Cat Cracker]

Thanks for the valuable feedback Pat, Andy , Jacob , Waiex , Moto.
I do like the idea of giving the electrolytic action a try. I don't see any surface rust in the tank but I haven't fully drained and borescoped it yet.
I guess I can always chase the coating route should it not work to my satisfaction.

The only issue I have, is that I am a very procedure driven person when it comes to any project. I guess my fear is not having the opportunity of a trial run etc. Having had a NASA boss for the last ten years of my career , well sometimes has its negatives when being experimental. For example, what is the best metallurgic anode to use? How much amperage to apply? duration? etc.

If any guidelines are known to be available, I appreciate any input.

Barry

[Cat Cracker]

Thanks Pat,
I just found this video you posted in 2018,,   https://www.youtube.com/watch?app=desktop&v=m-dNX8Q7Jh4

https://m.youtube.com/watch?v=m-dNX8Q7Jh4

This database of great information is priceless !

[Pat Conlon]

Thanks Barry, this is a group effort to build our Files.