MEP 002a fuel tank woes

[Keith_J]

Finally got my 002a home and started working on it. First was the fuel tank, once off, I saw the evidence of leaks. Sure enough, a line of pin holes in the bottom at the drain. The drain was concave in, making a trap for water that couldn't be drained.

Oh well, plenty of rust busting training helping mk out on his M37. I pulled the fittings, filler-strainer and started working. The fitting bosses are pop riveted AND soldered. I used a long reach propane torch to flame it clean ? Not really, there were flames but nothing that didn't go out by itself. This lifted the CARC and let the solder flow out. Drill out the pop rivets and then pull the fitting bosses. Now full rust repair can happen, as in full scrubbing of the bottom through the filler opening (the strainer support rails prevent full access). Also, big rust gobs can flow out. I have the strainer soaking in TSP, then will pickle in phosphoric acid. The strainer is bronze, copper phosphate does not dissolve in water so it can soak in TSP or phosphoric acid safely.

Flaming also loosened the rust . Looks like it is just the bottom. I can either cut back to the sound metal and weld in a flush patch (see mkcoen's M37 restoration thread for my abilities) or just solder the bottom solid. New metal is cheaper and faster.

I checked for water in the intake, no evidence. Engine turns over by hand (12" wrench) and no water in the oil. Just over-filled by 1/2". New air filter but nasty looking oil filter center gasket.

Been a busy morning, Took the air filter and control box off to work on the chipping paint and rust. While the phosphoric acid was working, i took the fuel filters off (bracket, all three) and pulled that service. All gaskets are shot and the fuel there smells really stake. The strainer is being cleaned by Pro Shot Copper Solvent IV. It looks new now.

The fuel tank is still waiting on major rust removal. I'll probably patch it with solder so the acid pickle job can go easier. The holes are small, just a dozen of them.

 

[Keith_J]

Well, looks like metal replacement is the best idea. The bottom and back, up to the long seam weld, will need replacement. I can either grind out the side seam welds, then edge weld to the sides or just do a butt weld. 18 gauge, easily bent for the radiused bottom in either case.

I'm going with the grind method since getting the metal clean is vital, the seam traps dirt and fuel. Still have the four corners to worry about but not long seams. I need to find my camera to post pictures.

 

[Keith_J]

Decided to flap wheel the outside of the corroded sections and patch instead of replace, just too much grinding.

Found another 5 pinholes. Drilled/ground all the holes back to good metal and TIG welded all shut. Took just 5 minutes of weld time but 2 hours of prep, the standard of rust weld repair.

This should be good enough for tank sealer, once I get the copper rivets in. McMaster-Carr has them in stock, I checked the old ones and they too have a steel mandrel, just like the MC ones. 1/8" diameter, 1/8"-3/16" range works. A bit too long for the filler neck but a copper washer underneath should work.

 

[Keith_J]

Back on it today. I see a problem with the drain on the tank, the tank where the drain attaches was concave, meaning it will not drain all water in the tank. I reversed this with a piece of pipe through the fuel gauge port, placing the tank on a layer of sand to cold form a positive sump.There is plenty of space for a 1/4" sump on the skid base.

Soldered all the bosses back in place, including the rivets. Now for the pressure test. Still need to find a gauge element. Just the dial, the float and magnet are fine.

 

[mkcoen]

Sounds like a replacement tank might have been an easier fix. Mayber 4 5-gallon jerry cans welded together?

 

[TexAndy]

Sounds like a replacement tank might have been an easier fix. Mayber 4 5-gallon jerry cans welded together?

Or go to the junkyard and retrofit an old automobile fuel tank maybe...

 

[mkcoen]

Or go to the junkyard and retrofit an old automobile fuel tank maybe...

That's the easy way out. There has to be a little challenge to it.

 

[Keith_J]

I like metal work. Just don't like rust.

It is now holding water. Was not able to locate powerful acid flux so I used a toilet bowl cleaner that has hydrochloric acid, it worked great. Even on the steel rivets since I couldn't find all copper.

Now to make sure it is sealed, then pickle once more with phosphoric acid and seal with POR brand sealer.

Tomorrow will be filter and associated gaskets. Three fuel pump gaskets, three fuel filters and the oil. Also need the 3/16 lynch pin for the throttle cable to governor. It had a giant cotter pin instead

The AN fittings were beat up, looking like the tank had been removed once before for cleaning. Yet they left the vent valve open

Got bored and took the gauge apart. Water had corroded the bearing. While apart, I touched up the background paint where rust had stained it. Polished the crystal, then glued it back together with silicone sealant.