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 - Tank Sender - Leak was my fault

Leaks from the warning light sender have been a thorn in my side for some time. The first culprit was the flange, next the cover plate and then the electrical terminal. I thought I had cured all the leaks only to find a pool of petrol on the garage floor after I had filled the tank to the top. After removing the sender once again I realised my error. Trying to do a good job I had made a flange gasket out of thick cork. I had assumed this would have plenty of give and provide a good seal. What had happened though as I tightened the securing screws the flange had sunk into the cork and was badly distorted. Fortunately I was able tap it flat without cracking it. It is now all back with a thin gasket and is leak free.

Jan T
J Targosz

I am about to replace my sender and could use some tips. I have the new viton seals and intend to use Hylomar sealant on the gaskets and the fastener threads. Did you use sealant and did you use anything to seal the threads?
Mike
Mike I

Hi Mike,

I also used Hylomar, both on the gaskets and the threads. Check your sender unit before installation. When in use it fills with petrol which can leak from the inspection plate and through the terminal screw - especially when you fill to the brim. I made up a new gasket and fitted new fibre washers to the terminal, again sealed with Hylomar. Fit the wire to the terminal before you insert the sender into the tank. It can be difficult to do this later. If you have any plastic pipe in the feed to the pump you may need an earth wire to one of the flange bolts for the purple warning lamp to work. Don't make my mistake and tighten the flange bolts up too hard. If you are using a soft gasket the flange will sink into the gasket and distort. Good news is if it leaks you can take out the sender from under the car without removing the tank. Mine has been out four times!

Good luck

Jan T
J Targosz

As well as checking the Sender Unit flange for flat 'truth', you may also may want to check the Petrol Tank surface itself where the Unit is attached. This area of the Tank is also often distorted. Under the Heads of the set screws,
I punch out small diameter Gasket Paper pieces and place them under the head of every screw. Fuel Resistant Sealant added is good insurance.

You may do all of the above and the main flange gasket can still leak if the dreaded cork gasket is used.

I use a neoprene(?),double lip seal purchased from Peter Edney in UK. (no
financial interest). Combined with the above checks, this gasket is brilliant with no leaks resulting.

Cheers
Rob Grantham
TF3719("Aramis"),TF9177("Athos").
Rob Grantham

Jan
Did you ever experience leakage at the terminal? I've never heard of that before. So you removed the both nuts and added a fiber washer under the bottom nut over the manufacturer's seal? Also why didn't you use the new viton seals which are supposed to last longer than cork?
Thanks
Mike
Mike I

Rob
Is the paper gasket the only washer you used under the screw heads? Also did you use them under the sensor cover screws?
Thanks
Mike
Mike I

Although I have the Peter Edney gasket on my car and have had no issues with it, I recommended it to someone on the Morris Minor Forum. He bought it, fitted it and it disintegrated!!
There are photos here
http://www.mmoc.org.uk/Messageboard/viewtopic.php?f=4&t=67458
It is obvious that the specification has changed and something has gone seriously wrong.

There is also a drawing of my Viton gasket on that link.
I found the cover plate is more difficult to seal than the flange as the pressure head of the fuel is over a much smaller surface area.

Regards
Declan
Declan Burns

Here's the drawing:


Declan Burns

Hi Mike,

I think it was Declan who alerted me to the possibility of a leak from the terminal and he was spot on. In normal use fuel fills the chamber in the sender and when the tank is full there is a fair amount of hydrostatic pressure forcing petrol out. In my sender there is a square head brass bolt that secures the switch contacts. This passes through a flat bottomed "U" paxolin insulator, a fibre washer, a small insulated sleeve, another fibre washer, a brass washer and a 4BA brass nut. These were probably 70 years old so I replaced both fibre washers and the sleeve and smeared them with Hylomar. I suspect a reason for some of the leaks is a loose terminal securing nut. You can only tighten it with a 4BA socket.

The car was raised up at the rear, I had drained the remaining petrol into a whole range of cans (there's over 3 gallons left when the purple light comes on) and I just wanted to finish the job so I made up a cork gasket. This time I have used material called "Novus Econosto" 0.75mm thick. It looks to be the same stuff carburettor gaskets are made from.

Cheers

Jan
J Targosz

The best that I have found is the gasket set sold by Abingdon Spares. Just follow their directions. Bud

Bud Krueger

Declan,

I have had the neoprene double lip seal fitted to our current TF1250
over ten(10) years with absolutely no leaks. Bit amazed it would 'disintegrate' in a Morris Minor !

Cheers
Rob Grantham
Rob Grantham

Rob,
It's strange but you can see it for yourself on the photos. It could have something to do with the ethanol in modern fuels.

Regards
Declan
Declan Burns

I doubt it Declan - any rubber that I can think of is resistant to ethanol. Many types of rubber are susceptible to hydrocarbons like petrol though. Many will swell like mad. My guess is that the one that disintegrated was not properly cured / vulcanised.
Dave H
Dave Hill

To make the job even easier, try Abingdon's newest product for the sender replacement, 3BA Allen Head screws, much easier to use when the tank is in the car than the original screws. part #19-157A
http://abingdonspares.com/product/3ba-screws-washers-set-of-6-sending-unit-stainless-allen-head/

EC Cooke

Reactivating "Moss Fuel Sending Unit Screw Error" Bud
Bud Krueger

I have been quite pleased with the neoprene (?) seal kit sold by Moss in my Morris Minor. Although on the Minor the sending unit is in the top of the tank and not soaked on fuel all the time. The kit comes with the round gasket and the rectangular one for the cover. After this was fitted no more fuel smells in the trunk.

John Quilter (TD8986)

I fear that folks using the A/S screws with an allen wrench will apply too much torque and will deform the soft metal flange. That distortion is a major factor in leakage. At least they're the right thread. Bud
Bud Krueger

This thread was discussed between 10/10/2017 and 12/10/2017

MG TD TF 1500 index

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