MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Help! Fuel tank blocked with tar like gunge

1st posting. My TD has been in storage for a number of years, now ready to be re-commissioned. Discovered that fuel feed from fuel tank blocked with solidified tar like gunge at outlet connection and for couple of inches into supply pipe. Tank drain plug removed and similar blockage. Cut through both blockages and drained tank. Two questions (1) Is this due to some deterioration of the old fuel or from treatment to internal lining of inner walls of tank at some time previously and decaying to the base of the tank? (2) is there some way to dissolve the embedded gunge on the base of the tank and drain off through the drain plug hole? Any advice would be gratefully received
I Smith

Hot caustic soda but be careful it is dangerous stuff

Jan t
J Targosz

Take it off. remove the cap plus the fuel sensor and take it to a radiator shop for a hot dip and strip.
You will have to re-paint it, but it will be cleaned. Then seal if needed. Replace fuel line( with copper is best. NOT rubber) then change or clean all filers. On pump and carbs.
Cost me around $150 plus self painted

M Grogan

Thank you Mr Grogan. Will certainly enquire re dip & strip although I was trying to avoid repainting due to difficulty in matching paintwork. Still wondering if the problem was caused by internal sealer becoming detached. Restoration was completed in California in the 1990's
I Smith

It could be the tank sealant or some congealed deposit from stale and evaporated fuel. If it were me I would take a look inside the tank as best as I could with a flashlight (but take care) to see if the lining is separating. If the liner looks ok then its a deposit from the fuel. You could try something like acetone or cellulose thinners to remove it, but check it doesn't damage the lining.
Dave H
Dave Hill

Dave I've drained the tank and allowing time for it to completely dry and will certainly use the torch. What surprised me when I found the outlets blocked was the degree of hardness in the tar like substance which I had to remove with a drill bit using finger rotation and removing gradually. Couldn't find any other postings covering the same problem but cannot be unique to this case. Many thanks for your response.
I Smith

Update to previous posting. Found very small LED torch and examined the walls of the compartment directly under the filler cap. Much of the black lining material has disappeared from some wall areas with only vertical streaks of the coating still in place. The metal looks very clean with no signs of rust. Perhaps one test might be to try and recover some more pieces of the 'gunge' material from the bottom outlets and test if it dissolves in acetone.
I Smith

Sounds like it is the lining then. Be careful with the word "torch" on here - to our American cousins it means something with a flame, that is why I used the term "flashlight". I made the same mistake a few weeks ago.
Dave H
Dave Hill

Dave - 'Torch' - Good to see you are still with us!
Thanks... Ian
I Smith

Ian
I think you will find the goop in your tank is just the residue of evaporating fuel returning back to nature
It must have sat for a while-?
I had similar with my Elan after a long shed stint
willy
William Revit

William Thanks for posting. I removed a small quantity of the solidified stuff via the drain plug and soaked it in cellulose thinner overnight but it has not dissolved which suggests it is the residue of the liner coating which has detached from the walls of the tank. The first response from Mr Targosz suggests using caustic soda and I wonder if this could work - any comments?
Ian
I Smith

It could work and it wouldn't damage the tank as steel is resistant to caustic soda. The other way that may remove it is to abrade it away with some coarse media inside - the best would be something like 1/2" granite chippings or new nuts and bolts - you want lots of sharp edges. Also add some water and rotate the whole thing for as long as you can so that you get a sliding bed of media in the bottom. Some kind of mechanical set up would be best.
Dave H
Dave Hill

It would be interesting to see if the stuff dissolved in petrol--this would tell you if it is fuel residue or in fact some sort of tank lining material
If it is tank lining ,i don't know what would get that out
willy
William Revit

Or
Injector cleaner
I don't know if you have Wynns products over there but their fuel injector tank additive is really potent and would probably clean it up if it's just dead fuel residue
Don't get it on your paintwork-----------
If it is available there, It comes in two strengths, The normal retail version and there is a stronger 'Trade' version which is used by workshops
This 'not for retail sale' marked bottle is the one to get------Don't breath the fumes or get it on your skin ---
William Revit

Catch-up. Dave Hill 09:35:16 / William Revit 11:00:12
Away for a couple of days and unable to continue tests. However, Good to have reassurance that caustic soda will not damage the metal in the tank. Assuming that a small test of the soda will dissolve the remaining pieces of the 'gunge' removed from around the drain hole it would be possible to direct a small dose of the caustic soda solution directly to the base of the tank using a pipe from the top filler opening and this would prevent dilution of any more of the lining material, leave for 6/12 hours and then drain, hopefully including the offending material. I will report back as soon as possible on any progress. Can safely report that 1st small test of the cellulose thinner had no effect on dissolving the 'gunge' so I have to assume offending material not petroleum based. Very grateful for all the replies and suggestions. Although the TD has been in storage for 3-4 years it's condition is still 1st class and a past concours winner
I Smith

Ian. Just before doing anything else it might be worth trying another solvent or two. Methylated spirits for one and if you can find some, a chlorinated solvent for another.
Dave H
Dave Hill

This thread was discussed between 07/10/2017 and 09/10/2017

MG TD TF 1500 index

This thread is from the archives. Join the live MG TD TF 1500 BBS now