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MG MGB Technical - Virgin - MG adventure

For a long time I have wanted a mgb roadster, now I have one. Its a 1964 B Roadster with pull handles, a 3 bearing engine with no overdrive (a later project, o/d to be fitted). It came with all the service history and even the original purchase receipt. She has her MOT and the mechanics have been well maintained over the years. Body is solid with a few rust spots here and there. In my younger days I trained as a tool fitter (now I wish I had trained as a mechanic!!) so Im looking forward to getting my hands dirty again and learning what make her tick.

My initial concern is an oil leak. It seems to stem from where the gear box and the engine seal together (my knowledge is currently very limited). At first I though the leak was constant. The drops would soak out to about 2 diameter on a sheet of newspaper over night, not a lot, however there is a lot of oil coating the underside of the car making me think its happening while driving. Yesterday I wiped down the area the drops form and left it over night 24 hours later we have no leak so I am ruling out a leak from the sump. Any ideas what I should do next?

Once the leak is fixed I had planned to protect the underside. Water jet and a good rub down with a wire brush before protecting her, is this a good idea? If so what should I use?

My adventure has just started out, I would be grateful to anyone who can give me some advise.

J Breslin

With a 3 bearing engine they have a 'scroll' on the end of the crank , instead of a rubber seal like the later engines, and that scroll keeps the oil in when the engine is running but tends to let it drip out when they are still, especially when the oil is very hot and 'thin'. This is quite 'normal'. It can get worse as the crank and bearings all wear, and its not really a problem unless the oil is really 'running' out while the engine is turning and the oil pressureised, IMO....a couple of drips overnight when stopped is pretty normal.

It can be helped of the crank is ground and new bearings are fitted.........

I dont know if a later type seal can be fitted here, it would certainly mean some machining work on the crank and the backplate......

My 3 brg engine always dripped a little here but it never caused me any trouble!.

A little oil on the underside will act as a nice rust inhibitor.....!

Chris Cooper

There's an old saying- "If an MG isn't leaking then it probably doesn't have any oil". While I don't totally believe that, a small oil leak is something you may have to live with. My 74.5 RB MGB has several leaks , it is after all a 30 year old car. They shouldn't be excessive, however, but I wouldn't be overly concerned. The leak itself sounds like a rear main seal. I beleive it requires near engine removal, I have not done it myself so I couldn't tell you the difficulty or expense of replacing it.
As for underside cleaning, a stiff brush and some Simple Green Automotive works well, as well as a good stream of water, or even better steam it. Many will say don't use the thick tar type undercoating for a protectant. I've heard good things about Por 15, an anti-rust coating. Good luck, ask a lot of questions and enjoy the ride.

There is a method of fitting a full circular type oil seal to the 3 main engine. Covered well at this web site
Other than that the rear main leak is one you will have to live with if you retain the slinger type seal.
Bill Young

Jason - The T series people have been battleing this problem for years. There are various methods devised to use modern lip seals, such as the one the Barney Gaylord shows in the link that Bill supplyed above, but they all have met with varied degrees of success. If the oil is not running out in a stream, I would just live with it (in fact, I do with our TD), just keeping an oil absorbing mat under the car in the garage. If anybody comments about your MG leaking when you are out and about, just assume a superior air and inform them that MGs don't leak, they just mark their territory and walk off. Cheers - Dave
David DuBois

As someone on this board said long ago:

"It's not leaking - it's just marking its territory."
Richard Smith

My favorite saying for oil leaks is:

Its not a leak. Its a flow through lubrication system.

I am in the same boat as you. New owner since last Sept. I started cleaning the whole bottom side as you are starting. I used a wood chisel 1" & 2" to dig all the grease and loose undercoating off. Then used degreaser and wire brush on drill to further clean. Anything bare, I sprayed with rust stop before finally using Truck Bed Liner paint to undercoat. Looks good and not tary. You can buy it flat or textured.

It get's better, especially with the help of the fine people here on this BBS. They never steer you wrong.

Best regards,
DT Toms

All of the above holds true. Congradulations on your MGB, As to your leak, watch your oil pressure, as long as its consistent and the car is not dumping a lot of oil I wouldn't be to concerned,
When the time arrives to put a new clutch in capitilize on the opportunity and carefully inspect all the above mentioned bits while the motor is out.
Their is an unkind joke among American mechanics...
Why don't the british build computers?.....You can't make them leak oil.
As for the undercoating, I've used a product called "Waxoil" which I purchased from the moss catalogue. It was easy to apply and seems to also help with road noise.
Good luck, and welcome to the worldwide community of MG lovers!
J A Kelly

Thanks all. I am feeling quite proud of the leak now and will live with it until the engine or clutch needs stripping. Now to start cleanig and protecting the underside, its going to be a messy job for sure!
J Breslin

The oil leak does a good job protecting the underside!

While you are under there check the fuel tank & the straps that hold it on to the car. In a pull door handle MGB they are basically MGA type and were rusty but salvageable on my '64 MGB.

The fuel pump should also be an MGA one, difficult to find now if you have the wrong type and want originality.

If you want an overdrive gearbox eventually then start looking now. My car was non-O/D and is now O/D. My impression is that not many 3 bearing MGBs had overdrives originally and so the gearboxes are not easy to find.

I personally would fit an oil cooler on a 3 brearing car if you don't hav one, they were optional in 1964,

The other rare parts are the instruments, they should all be Jaegar ones and not Smiths ones, and the grille which should have each bar rivetted in as a separate piece of metal, later ones were obviously cheaper to make and have all the bars pressed from a single piece of metal.

The water pump is unique to a 3 bearing engine, so make sure you have a spare.

Good luck, in a 3 bearing you have a super engine in a super car!

John. (johnprewer at hotmail dot com)
John Prewer

This thread was discussed between 28/06/2005 and 01/07/2005

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