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MG TD TF 1500 - TD gas tank sending unit

I just replaced the sender unit in my tank and I thought everything was fine and dandy until I went down and filled the tank. Darn thing is leaking and I can't stop it. I am pretty sure it is leaking from the cap on the exterior of the unit. I got it to a stop last night and today it is drip drip drip again. Anybody have some thoughts? I am sure it is not coming from the 6 screws that hold the until to the tank. And I did put the Viton gaskets on it.

Thanks,

Rich

www.mgtd.co.nr
Rich King TD 8732

Rich as you know the entire inside of the sender fills with fuel so the seal on the sender wire connector lug has to be good as well.

Perhaps I misunderstood what you are telling me. Regards, tom
tm peterson

Leaking from the four screw back plate or the terminal screw?
George Butz

Tom, yes I am aware the inside fills with gas. I am almost positive that is where it is leaking from. At this very moment I got it to stop or slow down leaking. We will see. george you understood perfectly. I had a hard time explaining what I meant.

Rich
Rich King TD 8732

Did you use a gasket sealant? I put new gaskets on and had a small leak until I used a permatex gasket sealant (the one they advertise as good for fuel
)
Geoffrey M Baker

Most of all be careful with explosion hazard, don't use a droplight with an incandescent bulb, keep good ventilation, etc. The terminal stud seal often leaks, remove the nut/wire and make sure the inner nut is snug- not easy to do with it on the tank but can be done. That leak runs all over the place so try that first. George
George Butz

Moss has a sender sealing kit that includes a neoprene round gasket and a rectangular gasket for the cover. Recently fitted one to each of my Morris Minors with good success but admittedly these senders are mounted in the top of the tank so are not submerged in fuel all the time.
John Quilter (TD8986)

I had a similar leak, the more fuel in the tank the more pressure and the worse the drip.
I wasn't sure if the fuel in the tank had to be below the sender so I waited for the low fuel light to come on and then drove a few more miles.
I used one of those little screwdrivers with a 90 degree bend, I've had it for years and years and this was its first use, I knew it would come in handy!
I removed the cover and the paper gasket was in trouble so I cut a new one from cork using a sharpened piece of copper tube for the bolt holes and a scalpel for the outside edge, it was made in no time and went back just as quickly. Problem solved, for now at least if what they say about ethenol in the fuel is true.
Cliff Harvey

The only sender gasket set that I would buy is the one from Abingdon Spares. Bud


Bud Krueger

I had the same problem after I a bought a new fuel tank and sender unit. The sender unit leaked like a sieve even though the 6 screws were snug against the gasket. In the end, I took off the tank (again) and used the permatex gas sealant to do a proper job. It has not leaked since but a real pain to get right.
Richard
R A B Wilson

Some of the sender units on the market have screws with the wrong thread. This caused a leak on mine. I had to re-use the old screws. I used Reinzoplast as a sealant.
Regards
Declan
D Burns

Bulk discussion on this subject in the Archive. Quality of the senders is very poor, dont be surprised if the lip on the connection chamber is not flat and the terminal stud is not sealed correctly.
G Evans

Well for now it is not leaking and it has been 24hrs... Just went for a quick ride to bounce it around a little and still good... I did not use a sealant on it. If the leak starts again I will check that nut at the top as mentioned. Then I will try the sealant. Hopefully is just doesn't leak again. Thanks for all the help guys!

And D Burns: I bought a new set of screws from Moss that were intended for original takes, which mine is. I did not like the way they screwed in. They didn't feel right. I used the old screws.

Rich
Rich King TD 8732

I have not had this unit apart yet, but I had a similar problem with a different car.

Question: do the bolts go through to the gasoline? If so, it's possible that the threads are leaking and no matter what you do with the gaskets, they will wick gasoline.

Just a thought.

....
MAndrus

I just received an email from 'Bobbie', one of the experts at Abingdon Spares before it was sold. It would appear that she's monitoring the forum, but can't reply. She wrote:
"I am having difficulty registering to reply on the MG BBS website concerning the leaking Sending Unit. You are correct that the Sending Unit should have been purchased from us in Walpole, NH. This is due to the proper gasket material and sealant recommended for the screws.

Would you please tell the gentleman that he should change the oblong and electric stud gasket as well as the large round one."

Bud
Bud Krueger

Now that's what I call service!. Even after the business has been sold Bobbie is still looking after her customers. Talk about above & beyond! Not only does Moss sell screws with the incorrect thread which WILL butcher the tank it also supplies the incorrect gasket. I've dealt with both companies & in terms of service & quality of parts there is just no comparison. Chalk & cheese! I do hope the new AS owners continue to maintain this exceptional standard. Cheers
Peter TD 5801
P Hehir

One of the problems with these units is that the metal is thin enough that when you screw it down it actually deforms. I saw this on the round section, it looked "fluted" as the metal was pressed down at every screw point but not in between. I ended up using a hammer to lightly and carefully flatten it down all around. Then I used permatex gasket sealant. Don't overtighten!
Geoffrey M Baker

I asked this question on another thread & never got a reply so I'll try again. Can anyone identify the thread on the knurled machine screw that secures the sender signal wire? I have an original sender unit, the tin can type, with a broken stud, which I'll drill & remove with an Eazyout. I'd like to replace it at the same time with the correctly threaded knurled screw. Seems it's impossible to find the correct knurled machine screw so I'll have to knock up something that looks close. Probably BA but who knows.. Cheers
Peter TD 5801
P Hehir

I had purchased some screws from Moss but they were the wrong thread. Doug Pelton had the correct ones (The Frame Up).
Mike
Mike Hart

Thanks Bud for Bobbie's message. I still have no leak. However that could change any second right? haha. If I encounter more problems in the future I will steer towards Abingdon Spares.

Thanks you all.

Rich
Rich King TD 8732

This thread was discussed between 30/06/2015 and 12/07/2015

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