Tank lining the M-715

[jeepdan]

I was going to use POR 15 tank sealant in this tank due to minor rust on bottom inside as well as I need to patch a screw hole drilled into the bottom.
This sealant has worked very well for me in the past, but this tank presents two problems; getting to and removing the intake screen. And #2, the baffle that really obstructs access to the other side of tank to get it dried and coated.
Has anyone done this?

[Don Cavey]

Since it is so much work and a lot of unknown, I bit the bullet and just got a new tank made by one of our members here. I think if you add up the time and money spent and then if it doesn't work and you have to do it again etc., to me it was cost effective. It has worked well.

Just a thought though...

[maskale]

I understand the trouble of getting a new tank. But since u already have one to pull measurements off I would build or get one made.

If ur not worried about like for like there are tanks lots of universal tanks out there for less.

I have always found short cutting when it comes to this sort of thing is not worth it in the long run.

Brakes, fuel and electrical will always come back an get u when u least expect it.

[jeepdan]

Thanks for the advice.
I just inspected the fuel tank interior a few minutes ago after spending eight hours yesterday sloshing around POR 15's Marine Clean mixed with hot water to remove the sludge and varnish. This would have been the first step before using their tank sealer.
Anyhow, after giving the tank a good cleaning, I have discovered that it is not rusty at all inside at least on the side that you can see.
Now, if someone hadn't drilled a hole in the bottom, I would be on easy street.
I will fix the hole and then give the outside a few coats of POR 15 black.
What is really rusty is the sender unit.

[jpsnblood]

I am financially challenged.
I have repaired more than one tank.
I have heard bad thongs about eastwoods POR tank sealant.
I used muriatic acid and immediately rinsed and used an epoxy tank sealant ( I think Randyscycle recommended it)
My truck is under construction. The tank has sit for two years with gas in it.
I have had no leaks and the filters in the fuel line look good, no sealant.
You did not say where the leak is.
If there is solid metal, not thinned by rust. I have had good luck brazing the hole shut. That worked real well on small holes on top of tank.
If you have a screw hole on bottom ( it is not the drain bung is it?) it can be filled by MIG or TIG welding.
BEFORE WELDING OR BRAZING ON A FUEL TANK. THE TANK SHOULD BE BOILED OUT BY A RADIATOR SHOP.
I am poor so I repeatedly used strong soap and water and filled the tank full,flipped it, shook it and prayed.(praying is never wrong at my house but it is not a good way to keep from getting blown up)
When I was brazing holes shut the tank blew air out a little and made some spooky sounds due to the expansion of the heated air in the tank. I knew there were no fumes left in that tank but man that is scarey first time you see it.
If you are interested here is a link for the system I used.
http://www.caswellplating.com/restoration-aids.html?p=2
If you have the money by all means by a new tank.
Make sure you replace the hard lines if you have rust issues.
Good luck and be safe.

[jeepdan]

My CJ-3B tank was sealed with POR 15 tank sealant six years ago, it was a mess before I started. It has held up well. The trick is you have to follow the instructions completely to get ALL of the varnish out, treat with the etching prep and then make sure it is COMPLETELY dry before adding the sealant. It takes a light bulb inside of the tank for heat and a shop vac to force air into it for drying.
A real pain requiring three or four days of prep. It looks like it would be very difficult to do with a M-715 tank.
Anyhow the pipe plug was siezed in the tank, I had to drill a 3/8" hole through the center of the plug to remove it without damaging the tank bung.
The previous owner seeing the frozen plug, must have drilled a 1/8" hole in the tank to remove the water/old gas and then put a screw in with a rubber washer to reseal.
I could purge the tank with inert gas while mig welding, but I'm to scared
I have repaired holes successfully in a couple of tanks with Devcon Plastic Steel.

[jpsnblood]

I hear ya
That reading the instructions thing does help.
Sounds like you have a solid tank.
On my budget (LOL) I would repair it.
The inert gas idea sounds good.
I had thought of seriously soap and water over a period of days and for extra safety filling the tank almost full with water and brazing the holes with a oxy/acetylene torch.
I think it sounds like you have the safety issue covered.
I remember in one of my stacks of speed shop catalogs. Some one makes a kit to put a drain in one of the newer auto transmission pan.
I think the first step was to drill a hole in the pan.
You probably have to have access to the back of the pan, witch would be a pain in the fuel tank. But with the fuel gauge sensor removed, I think it could be done.
Nobody would notice two fuel drain bungs.
Heck put a 1/8 screw with some of that Devcon stuff on it and seal the tank with a product that you like.
I am attaching a picture of before and after a muriatic acid rince.
Muratic acid will flash rust so fast, you woukd not believe it.

after

Again I wish you luck and be safe

[maskale]

Its not cheap, but evaporust works really well and doesn't flash rust. No you don't need to fill your tank, just keep the tank on each of its sides for the required time.

Those trans bungs he talks about do require you to hold a back up, there are plenty of creative ways of doing that though.

I would weld it. If you dont smell fumes then you are fine. I usually rinse with degreaser and that gets everything out. If you put a screw with a rubber washer you will find your self checking it make sure its not leaking. Weld it and be done.

If you go the screw route put the screw in then your tank sealant.

[jpsnblood]

I also had good results using evaporust.
I got it from caswell plating .
It is pricey.
But for small jobs it is great.
It seems like it was biodegradable also another plus!