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MG TD TF 1500 - Valve cover breather tube

I have a nicely restored 1953 MG TD (photo attached).
There is a rubber hose about 1/2" in diameter attached to a metal tube coming up vertically out of the rocker arm cover.
This just hangs over the side of the engine and seems to drip a bit of oil on the manifold.

Should this tube be connected to anything???

Bill from Ann Arbor, Michigan

W Chandler

If I am visualising your situation correctly, the tube you describe was linked to the air cleaner which then feeds the carburetors. I suspect that you have after market aid cleaners on the carbs (shiny S&H things?).

The original intention was to create a small vacuum in the rocker box which reduces the sump pressure and reduces (hah!) the oil leak from the back of the engine into the clutch housing.

You can put a line into the back of one of the air filters to do the same job.

Ian Bowers

Bill - your TD does indeed look great!

A picture of the carb side of your engine would be helpful. I assume you do not have the original factory air-cleaner set-up, as that encompasses everything about which you write. There should be a T-shaped aluminum air intake manifold that bolts to the two carb throats, and a round oil-bath oil cleaner that sits at the other end of the T, atop the valve cover. See a picture of one on eBay: 320790456097 A rubber hose connects the valve cover with the oil bath, and that is where the excess oil is supposed to go. You probably have a pair of after-market air filters or bnothing at all; again, a photo would be helpful.

They aren't cheap but they are on eBay from time to time. Try to get one that is complete with clamp, support stud and nut, central post and wing-nut. The aluminum polishes nicely, and the sir cleaner is painted black

Tom Lange
Bar Harbor, Maine
t lange

Here is a photo of the carb system - notice the black hose on top.

W Chandler


Looks like Tom and I have problems with the word 'air', I set it as 'aid' and Tom as 'sir'!

I understand that you have the original cleaner, so now you have an interesting conundrum.

The cleaners you have come with a reputation of strangling the air flow, so are not rated highly without changing the gauze and filter, and the original aluminium ones are also said to reduce air flow. And all that reduces performance.

If performance matters, then use trumpets, and accept the increased drip of oil from the back of the engine. If originality matters, install the bath and ducts, along with connecting pipe from the rocker cover to the oil bath. But, quite honestly I would think of ditching the ones in place now (or flog then on EBay!).

I suspect that there will be others who disagree, in a completely gentlemanly manner, as usual.

Ian Bowers

Ian, you don't like those shiney things? I put them on mine when I acquired the car because I thought they would look cool! "If it don't go, chrome it!" logic.

Bill, I have the same 90 degree hose coming up but I just put a plug/hose clamp on the end of it based on advice from this board way back when. No leaks! I was concerned about plugging something that was designed to be open but I did it anyway. I think Moss sells a "vented" plug for this purpose (#226-000) but they want $36.95 USD for it! I don't think so.

efh Haskell

Got it in one, Ed!

When I took on the TF it was covered in shiny bits where for the original builders paint had ruled. I have been following a policy of getting back to where it started, as long as you can see it. The hidden bits are upgraded to make life easier.

A leak free engine is a masterpiece of careful reassembly and use of the bits that make life more satisfying.

But then many others will disagreee and also be right by their measures.

Ian Bowers

MOss did sell the small vent that fits in the Valve Cover to compensate for the breather tube to the original setup. I think that would be better than that pipe setup IMHO. Nice car...
Tom Maine (TD8105)

I used the moss plug for many years until I found an original manifold and air cleaner. They have a vent hole but are designed so oil will not come out (well, not much will come out).
Bruce Cunha

I took my TF back to factory specs on venting the crank case. I have no crank case leaks! My air cleaners have the hose between the front AC and valve cover installed and the engine runs beautifully. PJ

P Jennings

Sounds like you have the TF filtes as do mine, They reqire a diferent setup and diff blow tube which uses the TF filters, Had to find NOt easy
Only blow into one filter.

Ellis Carlton

To do a tidy job on a TD and still use the pancake filters (ideally Vokes as origianlly on the TF), you will need to get hold of a TF rocker box cover. As has been hinted above they are not easy to find, but around 2 a year turn up on EBay. Then cut a hole and weld 1.5in of 1/2 in pipe on to the back of the forward filter, at around the 10.00 o-clock position looking from the side. Join the box and filter with rubber tube.

If you feel inclined, you can cut off and weld up the original breather tube hole on a TD cover (which are much more easily found) and replace it with a horizontal tube on the carb side of the cover, as shown in the picture above.

Ian Bowers

This thread was discussed between 14/11/2011 and 16/11/2011

MG TD TF 1500 index

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