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MG MGB Technical - fuel filter. How much crap?

How dirty should the fuel filter be. While I was poking around under the hood, I noticed my fuel filter was brown (Usually clear). Upon closer inspection I could see that it was almost half filled with brown sooty gunk.

Now, I know the vehicle has not been run for a number of years, and perhaps it was old bad gas. The PO said he had the tank acid washed, which I understand is not good unless it is somehow sealed. Am I going to be replacing a fuel tank in the near future? How near future, can I make it through the summer?

Thanks all.

Ken
70 b
Ken Harris

The answer, of course, is "none."

Of course the filter is there because in the real world things get dirty or rust. If the PO really didn't seal the tank in any manner after "acid washing" (also known as pickling or etching) then any little water in the fuel could start corrosion.

Interestingly, phosphoric acid tends to leave a very light coating of phosphate on the surface of the steel that protects it until abraded off. That's why there is a "neutralizer" step in the tank slushing process (also to kill any acid still in the seams).

The rust could be either wafting down from above the fuel line and is less of an issue as it is only from humidity in an undisturbed tank and should "wash out" soon, or from a small pool of water at the bottom of the fuel. The latter is much worse as it will hole the tank given time.

I'd also ask myself "Why would the tank be "acid washed" in the first place?" and wonder at the condition of the hard fuel lines as well.

Personally, I'd plan on finishing the slushing process (re-do the etching) and watch my fuel lines for leaks. Also, keep changing the filters and don't forget to clean the screen "filter" in the pump!

Mike!
mike!

How long did it take for the filter to get where it is - half filled with brown sooty gunk? If it's been on there for years, you had it coming. If it's only been months, you've got a rust problem.

With a non-rusty tank and unpolluted gasoline, a fuel filter will go forever without clogging or filling with crud. The only time I've found a filter actually clogged was when there was a ton of water in the fuel (car had been in a flood), or an accumulation of rust particles from a problem gas tank.

I'd drain the old gas from the entire system and change the filter. Make sure to get another you can see through. If it gets dirty again in several months, then as mike says, you need to attend to the gas tank (or steel lines). The replacement tanks are adequate, but not great. If your tank can be repaired - say professionally etched and resealed - don't discount that option.

Matt Kulka

Found a ton of junk in my clear filter and gass looked reddish. Cars started sputtering. Pilled carbs and float chambers coverd in gritty red, rust film. Getting new tank. Took 500 miles.
Dennis Pantano

Once rust particles start coming out of a tank, things deteriorate quickly. I restored a fuel pump for a friend and told him that he needed to do something about his tank since I found a significant amount of rust particles in the pump. He chose to ignore my warning and about 6 months later was bringing the pump back because it had "quit". While he was stil with me, I opened the pump and he was horrified to see the inside of the pump PACKED with rust particles - it looked like the coffee grounds container of an expresso machine. His only two comments were, "let me know how much I owe you to repair the pump again" and, "I am on my way to get a new tank". By the way, in 25 years of restoring SU fuel pumps, that is the only time I have seen enough rust in a pump to stop it from operating. It is wise, however to take any rust accumulation in filters or float bowls as a serious warning about the condition of the tank. Cheers - Dave
David DuBois

To agree with David - one of the filters I saw plugged with crud was on an air cooled VW. The pump has a cap you can remove to get to a plastic screen. Exactly as you described, upon the screen was a pile of rust in chunks a bit larger than coarse ground coffee.

I suggested Ken replace his filter and keep an eye on it in the hopes the brown sludge he saw was simply deteriorated gasoline left in the filter for the years the car has not run.

Ken, if the rust returns, replace the tank as soon as possible. Some rust particles are small enough to make it through the filter. These particles get into the engine and eat your piston rings. Unfortunately, I know this from personal experience.
Matt Kulka

I disagree about needing a new tank unless his leaks. You can etch and slush the tank yourself in an easy weekend (or frantic afternoon). Doing so seals all pin-holes, eliminates rust (forever) and is much cheaper than a new tank.

I am still suspicious as to why the PO had it etched in the first place and believe there is more rust hiding in the lines.

Mike!
mike!

This thread was discussed between 08/07/2004 and 09/07/2004

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