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MG MG Y Type - Various fuel-related component questions

Question 1: Is there a source in the USA for various Y-Type bits? I hate to order from NTG and pay shipping for a few small parts. I need the fuel filler grommet that goes in the inner wing and a few other small bits like that which I forgot to order last time.

Question 2: Can I assume the gasket for the fuel sender cover plate is the same as TD? Not the round seal between sender body and tank, but the one which covers the innards of the sender itself.

Question 3: How does the fuel sender function? There is only one lead coming from the unit, and the sender body is isolated from the rest of the chassis and therefore isolated from ground. How is the circuit completed?

Question 4: Is it normal for the fuel sender to fill up with fuel? If it isn't normal, can this be remedied or do I need a new sender unit?

Question 5: What should the resistance measure for the sender between full and empty?

Thanks for any advice!
Steve Simmons

1. Abingdon Spares used to have a few Y bits. Don't know if they still do but even if they have them there never was much. Otherwise there is little choice but NTG if you want a full range of parts,with at least some assurance that they will be right.As I recall the inner grommet for the fuel pipe is simply a rubber hose and if you knew the inside and outside measurements and length you should be able to source it locally.

2. I don't recall any gasket as you are describing it. The sender unit is the same as TC/TD but the arm to the float is a different length and shape. If you have the original do not dispose of it. John Marks in the UK can rebuild it. If you get a new sender you will have to replace the arm and copy from the old one. There are baffels in the tank and if the arm is not right the float will bind on the baffels.

3. Too long ago now and I can't remember that detail. But my TC, which I can see only has one terminal and lead so the unit must be grounded.

4. I think it is normal for the sender unit to fill with fuel.

5. No idea.

Terry
Terry O'Brien

Thanks Terry.

1. The inner grommet has some sort of retainer rung to hold it in place. In the Y-Type parts list the grommet appears to be a disc of some sort, perhaps rubber. I guess I can make one somehow.

2. There is a cover plate on the sender where you can inspect the insides of the unit. It appears there was a paper gasket there. Photo of the unit attached.

3. The only way I can see that the sender could ground would be if it does so through the fuel, then the tank and finally the tank securing bolts. The sender itself sits on a paper gasket and the screws are supposed to have sealer on them. I'm puzzled!

Thanks for the info!

Steve Simmons

Your photo looks like a perfect candidate for a John Marks rebuild. Checked the archives on the TD BBS and the ground to the sender unit is through the fuel line to the petrol pump. The petrol pump is grounded. Your fuel line must be all metal for the ground to work. Terry
Terry O'Brien

I would suggest getting a new one from Moss and just soldering your original arm to the new unit making certain that the orientation is correct. Then just exchange the float as it just pops in place.
Sandy
Sandy Sanders

Terry, I can see how the fuel line could bring a ground to the tank, but the sender is still isolated from the tank itself. I wonder if the circuit is completed through the gasoline itself? Kinda scary!

Sandy, I'm not sure the unit is bad. It's just dirty. Someone got a bit of undercoating on it but I've cleaned that off do bare metal and put a nice coat of POR15 on the unit. If I can figure out the resistance numbers it should show then I can verify it's good before moving on.

I don't have a photo of the sender painted, but here is a shot of it stripped down. The liquid on the sender is an acid etch in preparation for painting.

Steve Simmons

...and here is a photo of the painted tank. It was not yet dry so the final finish is not so glossy. It's a semi-gloss black. I polished the brass manufacturer's tag and plan to clear coat it. Why, I don't know, since no one will ever see it unless they remove the fuel tank from the car! A nice surprise for the next owner perhaps. :)

Steve Simmons

Steve-
Sat with Bob Seymour at a VSCCA meeting not long ago and he indicated aside from the listed items, he had a box of what he believed to be misc. Y rubber items. Didn't get around to chasing them down. Worth an e-mail.

Paul
Paul Gaynor

Steve

Re 1) NTG are about the only place I know where you can get this piece.

Re 2) The sender is the same as fitted to the TD and the Z Magnette, and a slew of other Brit. cars so yes.

Re 3) I have a technical document I was thinking about posting on this, so watch this space, as they say - well the website for the news of the posting. Just getting sorted after being away.

Re 4) New senders are cheap and easy to get hold of - check eBay for US Seller NOSLOCATORS, they are the cheapest I have found so far, but Abingdon Spares or Moss will also work for you.

Re 5) This is covered in the article. Watch out in the next few days.

Paul
Paul Barrow

Steve (and anyone else who is interested) check out the News page at www.mgytypes.org as I have added the atricle on testing the sender and fuel gauge now.

Paul
Paul Barrow

Thanks Paul! I'll give it a read tonight.

In the mean time, I have been told that the sender gets its ground through the screws securing it to the fuel tank. Assuming there is sealant on the threads, that sure is a tiny bit of metal to metal contact to make a circuit through! I may add a ground wire between the car's frame and one of the sender cover screws.

Paul, are you saying that the entire sender is the same, or is the arm different as Sandy mentions?
Steve Simmons

Steve

The entire sender & arm is the same.

Paul
Paul Barrow

Forgot to add to my last - if you have any questions after reading the article, please ask me and I will endeavor to find out the answer and enhance the post.

Paul
Paul Barrow

I have one. How does the sender measure resistance across the windings if it's full of fuel? Would that not short the windings and give a constant and false reading?
Steve Simmons

Steve

As the article says - 9 ohms = full, 1 ohm = empty, 0 ohms = a short circuit.

The sender doesnt measure anything - the gauge on the other hand measures things. So with a load of 9 ohms resistance the gauge will read full, 1 ohm it will show empty. The gauge is effectively and ohmmeter: so the greater the resistance, the higher the gauge reads.

Maybe I am not understanding your question (after all, my electronics knowledge is pretty basic).

Paul
Paul Barrow

I understand how resistance is interpreted by the gauge. The question is regarding the sender coil being submerged in a conductive liquid. Does this not short the sender coil and therefore give a reading of zero ohms to the gauge?
Steve Simmons

Ok, a bit of confusion here. NTG lists the YA / YB sender as a different item than TC/TD/TF which are all the same.

I tried to look up the sender in a YB parts list, but I can't seem to locate it anywhere.
Steve Simmons

Steve

Its OK, you can trust me on this one! If you had a copy of the Alternate Parts List you would be able to see what you are after! It certainly is the same as Z Magnette and MGA - might have thrown you off course by saying TD though - sorry!

Paul
Paul Barrow

Ok, that makes more sense, as the TD sender is an on/off unit. I'll look into MGA senders if I can't get this one working properly.
Steve Simmons

Abingdon Spares, Moss are the easiest routes, but the cheapest if you have an eBay account is seller NOSLOCATORS.

Paul
Paul Barrow

Steve

To make this easy for you here is an eBay Motors listing.
http://cgi.ebay.com/ebaymotors/MGYA-MGYB-MGYT-MG-ZA-ZB-Magnette-Fuel-Tank-Sender_W0QQcmdZViewItemQQcategoryZ80739QQihZ004QQitemZ140145861053QQrdZ1QQsspagenameZWDVW

Frankly for $40 they are not worth fussing with.

Paul
Paul Barrow

It is 10 years or more since I refurbished my fuel tank and memory fades. The sender unit on Ebay loooks to me as to what you need. The arm is twice as long as a TC/TD and it looks about right. There is no way that a sender unit for a TC/TD will work in a Y and I remember disputing the bill over trying to use one. Terry
Terry O'Brien

That looks about right. Not entirely original looking but I'm not THAT picky. :)
Steve Simmons

I have bought a couple from them - for myself and others so they are correct.

Which bit (apart from the float being plastic vs brass) doesnt look correct to you Steve?

Paul
Paul Barrow

The raised areas around the center part of the housing. Take a look at the photo I posted of my original sender for reference. I also thought the cover was the wrong shape but now I think it's just the eBay photo. Still, I'm not that picky.
Steve Simmons

This thread was discussed between 04/08/2007 and 18/08/2007

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