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Mk3 Spitfire: Cleaning Fuel Tank Crud?


1969Mk3Spitfire

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I've just bought a restored Mk3 Spitfire.¬† The car has done less than 5 miles since it was MoT'd in December. Sadly, it appears as though the fuel tank has been untouched.¬† I managed to breakdown a mile from home during my first drive¬†ūüėí.¬† Fortunately, my wife was following me in my Audi A3 and I had the foresight to bring along¬†a tow rope.

Back at home, I removed the cover of the brand new looking fuel pump and it was absolutely full of rusty/crud.

What's the general consensus regarding cleaning the tank?

I've searched the Forum and I've seen suggestions of 2-3 flushes with caustic soda and a final flush with Machine Mart Rust Remover / phosphoric acid.

Is any form of painting required or desirable. If so, what's the best paint and how is it best applied?

Hopefully I'll be able to remove and clean the pump. I've not yet looked at fuel pipes or the carbs. 

Many thanks for any input/advice.  

 

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Clean the pump out, blow the fuel lines through.

pop the tank out, fill it with nuts and bolts (count them!) and shake a lot.

flush out regularly, and refit.  fit an inline fuel filter ( 3.2 V6 Vauxhall Vectra is easy fit and cheap) just before fuel pump ( easiest place)

dont paint inside. It comes off again sometimes, and clogs permanently.

repeat a few months later if filter clogs up. 

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I cleaned mine using the nuts and bolts method.  Then flushed, and a final rinse with phosphoric acid to hopefully convert any remaining rust.

Car is EFI so very sensitive to dirty fuel. But after nearly 30K no issues at all, and I have had the pump out and checked, still all clean.

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I agree the nut and bolt cleaning method works well.

However, I can't agree about 'paint'. I sealed the inside of the fuel tank on my Scimitar GTE using a POR-15 sealant kit bought from Frost. This was done about 4 years ago and POR-15 had recently been reformulated to resist unleaded and ethanol in fuel. The Scimitar has a Weber 38DGAS carb and the finest rust particles could pass through the filters and regularly, clogging the narrow idle circuits in the carb and causing rough tickover and snatchy progression.

Since I used the sealer, the filters have remained clean and the carb hasn't blocked. The car is used plenty, clocking up about 5k miles per year.

If you find the problem recurs, I would recommend the POR-15 sealant - it's a lot cheaper than a new tank!

Nigel

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2 minutes ago, Nigel Clark said:

I agree the nut and bolt cleaning method works well.

However, I can't agree about 'paint'. I sealed the inside of the fuel tank on my Scimitar GTE using a POR-15 sealant kit bought from Frost. This was done about 4 years ago and POR-15 had recently been reformulated to resist unleaded and ethanol in fuel. The Scimitar has a Weber 38DGAS carb and the finest rust particles could pass through the filters and regularly, clogging the narrow idle circuits in the carb and causing rough tickover and snatchy progression.

Since I used the sealer, the filters have remained clean and the carb hasn't blocked. The car is used plenty, clocking up about 5k miles per year.

If you find the problem recurs, I would recommend the POR-15 sealant - it's a lot cheaper than a new tank!

Nigel

+1 for tank sealer,i broke down a few times in my Herald when i restored it to the road after a 30 year layup.I used the stuff you slosh around inside and leave to go off for 4 days.

Been fine for 8 years so far.

Steve

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21 minutes ago, Nigel Clark said:

If you find the problem recurs, I would recommend the POR-15 sealant - it's a lot cheaper than a new tank!

I'm glad it worked for you, but it was POR15 sealant that forced me to buy a new tank, because it peels off in sheets that block the outlet completely. I know I probably did something wrong but I've since heard a LOT of similar stories, including from a professional outfit who I trust.

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1 hour ago, NonMember said:

I'm glad it worked for you, but it was POR15 sealant that forced me to buy a new tank, because it peels off in sheets that block the outlet completely. I know I probably did something wrong but I've since heard a LOT of similar stories, including from a professional outfit who I trust.

I thought this may be controversial!

How long ago did you use POR-15? I understand that POR-15 was reformulated for modern petrol around 5 years ago. I used the latest version and it's been fine.

I bought the whole kit, not just the sealer, and went through the whole process of using cleaner, rust treatment, drying out thoroughly and finally sloshing the sealant. It's been fine for 4 years and about 20k miles.

Nigel

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15 minutes ago, NonMember said:

I used it in 2018, bought new from Frost for that use, and it was the whole kit, so it's not an "old version" problem.

I wonder if we're using different fuel. I usually fill up with Tesco Momentum, or Shell V-Power there's no Tesco nearby when the car needs fuelling. Very occasionally I use other fuels.

Perhaps I've never put any ethanol containing petrol in the tank??

Nigel

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Many thanks to all for the replies.

My tank has now been removed and I plan to clean it first with caustic soda, then phosphoric acid, both with a (counted) handful of nuts and bolts.

The fuel line, which is new, seems fairly blocked as I can't blow it through. I'll try to use a foot pump.  I don't have access to an air compressor.

Next job will be the pump.  Is it likely to have damaged the valves, should i buy a service kit or clean it first to check?

 

 

 

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The gauze filter in the pump is actually quite good at blocking up catching anything large enough to cause valve damage.

I'm a little surprised you can't blow through the "new" pipe. Which end were you blowing from? I take it this was with both ends disconnected? Are there any bits of rubber hose in the length you were trying to blow through? The original Mk3 fuel pipe is all steel from the tank to the bit that sticks into the engine bay - the first bit of rubber is the one to the pump - but if yours has been replaced it may have lost the threaded coupling and gained some cheap rubber, which may not be ethanol resistant and may have swelled to the point where it closes off.

Or it may be full of rust despite being new...

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My everyday/only car back in the mid-seventies was a Spitfire Mk3. That suffered a rust blockage in the fuel line. It was immediately below the tank outlet, and I've heard that's quite a common place for it to happen.

It not a new problem!

Nigel

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2 hours ago, Pete Lewis said:

on the bottom entry tanks is it possible to drill through the union and extend a tube 25mm up from the bottom so it cant suck up debris , even my 52 minx had that design 

Pete

The simplest ideas are often the best. Shame Triumph never thought to do the same as Hillman.

Nigel

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At one point mid afternoon, I was convinced that the "nuts and bolts" comment was a new member initiation ceremony¬†ūüėĀ

It took me ages to figure-out how to rotate the tank to get the nuts and bolts back into the upper most baffle.  

I've now flushed it twice with caustic soda.  The emptied liquid looked like filthy engine oil and had a lot of suspended matter.  I'll flush it out one more time tomorrow and then a final flush with Machine Mart Rust Remover.  Before I put it back in the car I'll flush it one more time with some of the drained petrol.

The new fuel pipe is exactly as described above by NonMember, as it should be.  I put a foot pump on the pipe at the tank end and covered the engine bay rubber hose with a clean, white rag.  The pump built up quite a head of steam and then "pop".  The white rag looked like it had been shot at close range with a 12-bore filled with iron filings.  I put a bit of fuel in the tube, using a model aero engine primer bottle, and pumped it through until the rag (clean one each time) stayed clean.

I didn't remove the pump from the block, just the top housing as far as the diaphragm and gave it a good clean and blow out.  I'm assuming that it shouldn't be necessary to remove it completely?

The suggestion to add an in-line filter just prior to the pump seems to be a good idea.

All in all a good day, my third day of Triumph ownership.  Many thanks to you all for your advice.

Doubtless more posts to follow.......ūüėÉ

 

 

 

  

 

 

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as for filters ...theres loads the one from club shop  are metal/glass  and cleanable 

 plastic filters can end up with the tube stub being collapsed due to tight hose clips

or get a modern FI filter with hose fit ends (far more capacity ) 

Pete

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