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MG MGB Technical - Sender Unit Leak Again!!!

So the replacement new sender unit has been fitted and that one leaks!

Okay this time it doesn't leak from where the previous new one failed (around the plastic electrical node) but this one does from around the seal.

I first replaced it with the previous new seal and ring - it leaked!

Then after draining the tank yet again, I replaced the seal and ring with a brand new one - that leaks also.

So the tank is being drained again and I'll be taking the sender unit out again.

What am I doing wrong?

I've assembled it in this order from the tank.
Tank - Rubber Ring - Sender - Steel Ring (fully tightened up.

What I have noticed is that the two locating lugs on the sender do not find their corresponding holes in the tank until the steel ring is tightened.

I know the physics of it should work, but is it worth trying the sender unit in first then the rubber ring and finally the steel ring.

I do not want to revert to Hylomar if I can help it.

Help!

Andrew
Andrew McGee

Andrew. Do not know what to tell you. You might look to see what is keeping the rubber ring from providing an adequate seal. Perhaps the part is slightly warped?

As to installing the sending unit against the tank, then the rubber ring, then the retainer, this will not work. Made that mistake once and had massive fuel leaks from around the sending unit. Since the system is capable of working correctly, and the only change is the new part, I would look at the part to see how it differs from the original part. Since you have already received on defective part, it is perfectly possible to receive a second defective part as a replacement.

Les
Les Bengtson

Les

Thanks for your input again. Problem Solved!

My wife was out shopping, so a quick call to her to get some Hylomar and await her return.

Whilst she was away I took everything back out and clean it all up (it was dirty anyway, but still!).

I noticed two things, the lower notch on the tank was slightly bent inwards (I pulled that straight) and that both rings (when fitted) were coming away from one of the lugs when tightened.

So with a thin application of Hylomar to the tank and another to the reverse of the sender unit I reassembled it slowly and carefully bringing the steel ring back into contact with all three lugs.

Just taken it for a run and it has come back absolutely bone dry around the sender unit.

One thing, I hope I haven't worn the pump out and it has shifted over 200 litres of petrol this morning draining the tank on the numerous times that I had to do it.

Thanks again.

Andrew.

Andrew McGee

Don't you just hate it when you speak to soon....

Well the REPLACEMENT NEW sender unit is leaking IN THE SAME PLACE AS THE ORIGINAL NEW SENDER.

In otherwords it is leaking around the little black rubber seal where the white plastic electrical pick up is.

Another one to consign to the NAF list of components.

Oh well back on the phone to Moss again on Monday.....

Time to drain the tank again

Andrew.
Andrew McGee

Andrew. Sorry to hear that. A US company, Motorhead, lists bad parts at http://www.motorheadltd.com/bad_parts.htm and the fuel sending unit is listed there. Do not know why the links pasted here do not hot link, but the site is worth bookmarking.

Les
Les Bengtson

Les, it linked fine in the message. I think it just doesn't hotlink when editing. Interesting page. Just goes to show how it is usually better to rebuild old, original parts than by new, badly made ones.
Simon Jansen

Les, Thanks for the link. A great page with a huge amount of information.

Cheers , Pete.
Peter Thomas

Maybe use a gas sealing compound. I think you could seal anything with this. I use NAPA Hylomar HPF on both sides of the gasket. I also coat the threads with it too.
Frank Baker

Hats off to my guy at Moss UK, he's obviously concerned that all there sender units are faulty and will be speaking with Moss HQ to flag this up with them, but in the meanwhile he has said that another one will be sent to me by post so I can have another go at it.

Will keep you all posted.

Andrew.
A I McGee

As good as his word, the new one arrived in today's post, will fit it next week when I get back home, will let you all know then.....

Andrew
Andrew McGee

Andrew. Best of luck and, please, keep us updated over the next several months should there be a continuing problem. We only found out about the problems with the Lucas made rotors because several people posted the same problem. I, too, have just fitted a new sending unit, on a 79, which is not yet on the road. (Little incentive to work when the outside air temps are 110 deg F and the garage is not air conditioned.) I, too, will keep an eye on the new sending unit and post if it begins to show signs of leaking.

Les
Les Bengtson

Actually don't know whether I'll get to fit it next week as the car will be down at my local Bodyshop a bit earlier than planned. A friend of mine supplies vehicles for the TV and Film industry and they wanted a BGT to have an accident in one of our Soaps called Emerdale.

They chose not to use mine (fortunately) but he did take my reasonably good tailgate from my parts donor car. No problem there, until that his he rings me on Sunday evening (after we've had a couple of bottles of wine) and begs me to let him have the one of my car as they want to do a few takes of the "accident". Against my better judgement I let him.

The better tailgate was used and written off, mine was repainted Tahiti Blue and then NOT used in the event after all. So my Jubilee BGT is sat in the garage with no tailgate until it gets stripped and refinished in New Racing Green. However I was planning on having the drivers side sorted so whilst it's at the Bodyshop I think it will get done.

I hope this fine weather stays as it looks as though I'm in the midget for the next month or so!

Andrew
Andrew McGee

I had problems with the sending unit/fuel tank rubber seal leaking on my MGA. Replaced the rubber seal with a cork seal over 3 years ago, and everything has been fine since.
M. D.

It seems the problem is not with the sealing gasket, but rather a seal around the electrical connection on the unit.
Tom

Tom you are correct, however the five times that I had to do to get the outer rubber seal to stop pouring petrol out of it (and ruining out bitumin drive at the same time) never mind the amount of tank drainging that had to be done, did sort of annoy me after a little while.

And the fact that I have to do it all over again is rather irritating to say the least.

Andrew.
Andrew McGee

Andrew - Sorry to hear about your leak. Based on posts I've seen here and other boards, I found that I was able to replace the float on my sender and reuse the old sender.

The PO must have been in there before as an old carb float had been soldered to the sender arm sometime in the past.

Have you checked with MGOC. Maybe they have a better part.
PR Peterson

This thread was discussed between 15/07/2006 and 22/07/2006

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