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MG MGB Technical - Cleaning Petrol Residue from a tank

I am recommissioning my MGB after about 25 years of idleness and I find there is a brown residue in the stainless steel fuel tank which I need to clean out.

One possibility is to go to a local radiator repair place and have them clean it.They say they can do it.

Another is to wash it out myself with a suitable solvent (but which one?). Would soap and water work?

Obviously I want to get this right first time and do no damage.As you can imagine, I want it to be thoroughly clean.

Fitting the stainless steel tank all those years ago seems to have been a good decision - an ordinary tank would have been a write off.

Has anyone experience removing this kind of residue successfully?

sam christie

I have no idea how to deal with this problem, but I would dearly like to know how you took the picture :-))

Tony Oliver

Sam - I would take it to a radiator shop and let them clean it out instead of trying to deal with harsh and usually highly flammable solvents that can cause harm to you either from inhaling the fumes or immolating yourself.

One thing that is not toxic or flammable, would be a solution of molasses and hot water. This is supposed to be a good fuel tank cleaner. Cheers - Dave
D.W. DuBois

Thanks D.W. I think you are probably right. The chemicals seem to be unpleasant, unhealthy,dangerous and ineffective.

I have tested cellulose thinners, nail varnish remover, methylated spirits and petrol. None has worked. I tried white spirit which did not help either. Washing up liquid makes no difference.

But I did notice that hand cleanser cleaned the goo off my hands and does have an effect in the tank. I tried a rag soaked in hand cleanser but while it made headway it is not very practical.The hand cleanser is supposed to be environmentally friendly too.

I have no access to molasses so I will see what the radiator repairer can do on Monday.

I will report on how I get on.

And Tony, I will tell you how I took the picture in the next thrilling instalment.
sam christie

That brown stuff looks like the solid scaley scum left after old fuel has evaporated. -Usually sticky to touch

--A citrus based one if you are worried about fumes
Then you can give it a good flush out with hot soapey water, then to dry it out put the filler onto the exhaust of a warm idling car and get the tank hot. Be carefull,it doesn't take long to get very hot

William Revit

"I have tested cellulose thinners, nail varnish remover, methylated spirits and petrol. None has worked."

If none of those, especially petrol, removed any of the staining then I don't see it as a problem.
Paul Hunt

Since the 'goo' is not dissolved in petrol, leaving it alone would seem like an option but it has more or less blocked the pickup filter.The residue is like a syrup or a very thick varnish . I will be fitting a new sender/pick up unit (post 1976). Inside the tank probably looked like a lava lamp when the car was last on the move. (See picture - not a pretty sight).

I have had to replace the fuel pump. All the original flexible fuel line has had to be replaced though I think it was unleaded fuel did for them rather than the sludge.

I plan to try to sort out the fuel system working forwards, finishing off with the carburettors.

sam christie

Tony,I had the camera on the macro setting and I lowered in a small (1 shop) led torch on a string by the filler neck. The camera needs some light to focus (supplied by the torch) but most of the light for the picture was supplied by the flash on the camera which is very close to the lens.The picture was taken through the opening for the sender unit.

Last night I had aother go at the tank with hand cleanser using a 1/2" paintbrush screwed to a length of plastic conduit.I also had a small bronze brush fixed to a stick. I blobbed hand cleanser on the brush and scrubbed the inside of the tank repeatedly.I used the bronze brush for extra scrubbing.I worked for about 10 minutes and left it overnight.

The attached picture was taken this morning and although the job is not finished it seems hand cleanser works. The quantity of hand cleanser used so far amounts to less than a large cupful. No trip to the radiator repairer after all.

I will report on further progress.

sam christie

Picture and latest description makes me think of sugar!
Paul Hunt

Looking better

I'm still pushing for citrus degreaser------

You will probably find your hand cleaner is citrus based, so that might give you a clew that the degreaser will in fact work.
Also you can use degreaser in/on your carbs where using hand cleaner would be a bit iffy

William Revit

William, the hand cleanser does have a citrus smell and I think you are spot on about it. I will go out this afternoon and try to buy some citrus degreaser.

How do you recommend using it in the carbs? Strip them down and wash them ?

sam christie


As an ex "Old Dart" person who left Poynton, Cheshire, in 1968 to join the Australian Air Force;

I applaud you for your efforts to take the picture,

I admit to jealously for having access to a 1 GBP shop,

and I express,

My admiration for your ingenuity in solving the problem and,

The lengths to which you went to save a "Quid"

The more money you save on keeping classic cars on the road simply gives you more money to spend on drinking Draught Guinness (the Nectar of the Gods) of which I have had a few Pints over the last 50 years

Tony Oliver

Before setting off I took the precaution of phoning round but cannot find it anywhere in N.Ireland. I recall seeing citrus degreaser some years ago.I may have to order off eBay - all rather slow.
sam christie

With the carbs, I'd take the top off the float bowls and have a look at what you've got
That brown goop usually only arrives after a larger amount of fuel reduces down to nothing. I'm thinking you might not have it in the carbs if you are lucky

William Revit

photographyiam.The goop did not get to the float bowls but blocked the pick up filter in the tank. There could be other issues with the carburettors but that is another story.

Since the supplier unexpectedly wanted to charge an extra

sam christie

Looks pretty good from here, them pics really do come up well.-- Thanks for the credit but that's not what it's about for me ,just trying to help like everyone else on here-
I didn't think of it quick enough, but most pushbike shops usually keep the citrus degreaser for chain cleaning, It doesn't hurt their tyres and other rubber bits like some degreasers

William Revit

Did u try pressure pack carburetor cleaner? It says on the pack dissolves vanish.
Mike Ellsmore

I plan to try "Restore Sludge Remover" but I have no idea how well it works. My hope is to give the fuel system a final cleaning.

The makers claim-

"Sludge forms in the bottom of petrol tanks due to oxidization and condensation, perhaps due to the petrol tank having been left low on fuel for long periods of time without use. Temperature changes and fluctuations during this time can cause the components of the fuel to separate and bacteria to develop, turning to sludge which will block your fuel pick-up, injectors and pump. A good sludge remover treatment such as AMETECH RESTORE SLUDGE REMOVER will dissolve and disperse the sludge and prevent the formation of new sludge in the fuel system."

Apparently you add this to the petrol . I am not sure how well it would have worked applied directly as a cleaner to the challenging mess in my tank.

sam christie

I think additives probably have the best chance on a car which is running. My car is still some way from running again.

The cleaning method I used on the tank was very cheap but very effective and I can clearly see that it has worked.

I needed to take the tank off to do the job.This was reasonably easy and just as well for I discovered the sender/fuel pick up unit was in a very bad way and needed to be replaced.

The pick up filter was almost completely clogged but it had done its duty and protected the fuel pump and carburettors.

sam christie

That is the cleanest gas tank I think I have ever seen - congrats!

This thread was discussed between 30/05/2015 and 06/06/2015

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