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MG TD TF 1500 - Oil Leak, 53 TD

No B.S., is there anyone who has completly stopped the rear seal leak.? I have found many opinions and reports to read but is there a solution for a non-machinest?
Tom McNamara

I don't think there is a solution which doesn't involve machine work or very careful assembly.

Some claim to have gotten good results (tablespoon sized oil spots) with the stock parts. This black art is discussed in the archives. There's no way you're going to get good results if the crank is loose in its bearings, if the oil return scroll or alloy cap are chewed up, or if you're ham fisted about putting it all together.

Another technique is to modify the crank, rear bearing cap, and maybe the block (?) to accept a Chevy 350 rear oil seal. I'll bet this really works. I saw this mod discussed somewhere recently--maybe in the archives, Moss Motoring. I just don't remember right now. A disadvantage to this setup is that you loose the scroll on the crank--that's where the Chevy seal lives.

The third method is to fit an oil seal which rides on the rear flange of the crank. There are certain inherent advantages and disadvantages to this design. The advantage is that the stock oil return scroll is retained. Part of getting good results from a lip seal is putting a slinger and scroll in front of it so it has less work to do. The disadvantage is that the large diameter of the crank flange results in high surface feet per minute on the lip seal. Anyway, the fellows I know favor the Sure-Fixx seal in this design category, and I concur. It is possible to get good results with this piece. The creator of the Sure-Fixx claims that the seal operates at SFM within the manufacturer's (Chicago Rawhide) limits--I asked him. Installing one of these isn't difficult, but you've certainly got to RTFM.

Another method is to fit a catch can of some sort to the drain hole in the bell housing. I know this probably isn't what you had in mind, but I think a guy could make a very nice trick little metal container which wouldn't be too hard to remove and empty. Don't let it hang down too low. This has been discussed in TSO at various times, but people were using tuna cans etc. A very nice little TIG'd box would be a different story. Dont forget to vent.

Good luck.
Jack Williamson

I have read with great amusement all the comments regarding oil leaks. The leaks have done much to preserve our cars over the years. There is simply no rust in the middle from the continuous streams of oil blown to the back. When you have no leak, your probably have no oil! Seriously, carefull attention to assembly will minimize leaks with the stock setup. I have been unable to get even the modern front seal to stay dry- even replacing and polishing the pulley. Even if the crank does not leak, the valve cover, side plate, numerous oil lines, the transmission, speedo cable, or something else will. Keep cardboard under the car in the garage, drive it, enjoy, and let it leak! Of course, when the local T-club came to visit, it looked like the Valdez had docked in our driveway!
George Butz III

40 years ago, my dad used to say "If you've got a large oil leak you've got a problem. If you've got no oil leak you have an even bigger problem. But if you have a small oil leak, leave it alone. Things are exactly right".

Geoff Love
Geoffrey Love

The let 'er blow faction makes a very valid point about all that oil protecting the undercarriage.

The only part I don't like is oil coming out of the valve cover and oozing down to the ex manifold. Everyone at work jokes about the burnt oil smell which clings to me.

I know this has been covered a million times in different threads, but I just cant get oil to stop coming out of the TC-style cast aluminium valve on my car. I've got an o-ring on the oil filler cap, Earl's stat-o-seals under the tightening nuts, nice new gasket(s) lovingly contact cemented / siliconed / 3M weatherstripped to the head as the case may have been. I checked the cover with a Starrett straightedge and I'm not overtightening the nuts.

Next motor rebuild I'm going to mill a half round groove in the cover and a matching groove in the head and o-ring the !@#$%& thing.

I have not tried the neoprene gaskets. I was going to but an MG guru whose name would be instantly recognizable claimed they were worthless and put me off them. But has anyone else had a different experience?
Jack Williamson

I have to agree with George Butz. Leaky T's are a reality. Some of them are far worse than others. Our TF was not driven for some 24 years and expected it to leak like a sieve when we started it for the first time. After a refill of Castrol GTX 20-50, it only has minimal leakage. I do not add a half pint for 2000 miles of driving. I have no valve, tappet or oil line leaks. Front and rear seals are very minimal and are taken care of by good old cardboard.
I have found that bonding the cork valve cover gasket to the head with a little Permatex works better than bonding it to the cover. I did this on a A-H 100-6 and it never leaked in 10 years.
Leaks are part of the mystique of the "T". Drive and Drip.
Just remember these are in essence, engines designed in the 30's with seal and crank technology that is no different than our 1914 Model T.
colin stafford

To Jack Williamson:

Jack:

Does your aluminum valve cover have a vent tube? As you know, the original pressed steel valve cover had a vent tube brazed or welded on the side and this tube was connected directly to the oil bath air filter located beside it. When aftermarket individual air filters were added by owners, I believe it was the forward one which had a tube affixed to the back side to connect by flex hose with the tube on the valve cover.

The purpose of this was to supplement the "road draft" tube located on the rear tappet cover and assist it in lowering the internal crankcase pressures which were somewhat high on new engines and increased considerably with mileage. If your cover is without a venting tube connected to the intake system, it could very well be the source of the oil leakage. If so, practically no "normal" gasket sealing will ever work. The only way would be to drill the cover, tap it for a fitting or have one heliarced on, and go from there. (If originality isn't a priority, this would be the ideal time to incorporate a PCV valve as it helps a good deal in ventilating the crankcase and is very inexpensive as I'm sure you know. One from a Pinto 1600 cc should draw at about the rate for the MGTD.)

One would think that with the open end of the road draft tube there would be sufficient relief from pressure within the crankcase but it's clear it just isn't enough. Also, if this tube is plugged to a certain extent, which most of them seem to be, at least to some degree after a few thousand miles, crankcase pressures will build enormously with resultant oil leaks everywhere. Also, I'm not so sure the road draft tube is in an area of negative pressure. It could be in an area of positive pressure when the car is moving and actually be forcing pressures back inside the engine, the higher the speed, the greater the back pressure!

Also, I seem to recall seeing some pictures of the Ken Miles special TC racer which had an alloy cover of some sort. If I am correct, this cover had TWO ventilators on it which merely opened into the atmosphere, unconnected to any intake area. I imagine the designers of that little piece of dynamite put the ventilators on for some reason other than "swoopy-zoom" looks.

Now that I've written all this, you're going to tell me you have a breather tube and a clean road draft tube! But maybe not, and if not, at least that's something you can check out.

Best regards,

Mike Brown,
Seven Shop British
Mike Brown

Mike, thanks for your detailed reply. It's true, I do have a pipe running from the cover to one of the air cleaners. But maybe it doesn't have sufficient capacity. There's a little oil maze cast into the inside of the cover, and then a fairly small diameter fitting which connects to the hose going to the air cleaner.

The car's got an alloy tappet chest cover with two little breathers and no road draft tube. I just assumed these breather workeds--but who knows. There's certainly no air-moving-past-a-tube effect in play.

I'll have to think about this.

BTW, how is a PCV valve plumbed?

Thanks again.
Jack Williamson

To Jack:
I think I know the Guru you refer to and who advised me against the nitrile gaskets. However I had installed them prior to asking him and I beg to disagree. They work great and I have no leak whatsoever either from the valve cover - the original, pressed steel one - or from the tappet cover - also original. I recommend them without reservation - I am talking about the ones from Australia advertized in the OCC Bulletin.

Denis
Denis L. Baggi

Jack:

The PCV valve can go between either the valve/rocker cover or from one of the tappet covers and the actual intake manifold downstream from the carburetors. On the TD, you may have to tap into the manifold itself to place another "tube" fitting and if it has the "core plugs" on the end of the manifold balance tube, this would be an ideal place as it wouldn't deface the alloy itself.

The PCV valve is attached between two hoses and the action of the manifold vacuum causes a positive draft through the valve, thus sucking fumes from the rocker as the engine runs. This draft is controlled by an orifice within the valve sized for a particular engine. That's why one from a Pinto would be about right for your TD. One for a 350 Chev., for example, would draw too much. If you instal one, I think I'd remove the "Brillo pad" filter or whatever's presently in the rocker cover in order to ensure good draft.

Also, the PCV valve contains an anti-backfire feature so when the engine backfires under lean conditions, you don't experience a sump explosion...which my imagination rules should happen to someone like your ex-wife's new boyfriend while you're observing from a safe distance.

Hope this is detailed enough but if not, will provide more.

Best regards,

Mike Brown,
Seven Shop British
Mike Brown

Mike, if I plumbed the PCV valve to the tappet chest cover, I assume I'd block off it's existing two vents. If not, wouldn't there be a massive lean out--or does the action of the valve prevent that? Don't mean to be ignorant, I've just never onwed a car new enough to have one of these things.

I think this would be great, because the fumes coming out those vents more or less make their way into the cockpit. Not so great with top and curtains up.

Thanks.
Jack Williamson

Jack:

I think ducting the valve from the tappet side cover would work great. That's how it's done on the MGB. They have a tube on the forward tappet cover leading up to the direction of the manifold and fumes are taken through the valve from there. I hesitated to mention that because you already have a pipe in the rocker cover and I thought using that existing resource would simplify things. But, yes, by all means go for the tappet cover, especially given your problem with the fumes boiling out there already.

Also, the logical reasoning behind a road draft tube in the pre-smog days was to ensure the ever-present engine fumes would be vented into the slipstream beneath the chassis and not be drawn up into the cockpit/passenger area with resulting occupant nausea and discomfort. It makes one wonder why this apparently simple-minded concept was so lost to the makers of your aftermarket tappet covers whose inelegant solution to the problem set things back fifty years or more and ensured you'd be breathing fumes from the moment you started your engine with their product installed.

And, I think I'd block off the existing vents merely to ensure the fumes are drawn off by the PCV valve. If you left them open, it wouldn't change anything at the manifold because the orifice in the PCV valve draws a constant volume whether it's open to the atmosphere or to the crankcase. But you want it to suck the oil fumes, not clean air. The best possible solution is probably to leave the rocker cover hose in place along with the tappet cover modification. That way there is a positive suction on the system from both areas.

Also, I'm glad to note Denis' comment above respecting the nitrile gaskets. We've had very good results and no failures with them. I think you might try them in conjunction with the above suggestions and see what happens. Hopefully it'll solve the irritating oil loss from at least a couple of places.

Keep us posted.

Best regards,

Mike Brown,
Seven Shop British

Mike Brown

I remember a year or so ago downloading some material from another (I think) message board. There was a drawing and instructions for installing a rear sea that "will not leak." Here's a partial quote from the write up: "The whole job can be done for less than $200. USD. You'll also need a gasket kit, and one small-block GM rear oil seal, Fel-Pro #BS4013 or its equivalent, a heavy duty, double-lipped, silicone split seal used on a wide variety of GM engines from the '60s through today. About $8-11."
The job requires some machine work.

If you are interested, you might contact the author. The name and address is:

Andy Bradley
Bradley Engineering
Mt. Vernon, WA, 98273
Dave Geissinger

When I bought my TD, the PO had removed the oil bath air filter and installed two pancake type filters on the SU's. It had the original valve cover and the PO apparently simply left the vent to the old air cleaner open.
I bought a mushroomed-shaped aluminum "plug" that fit
down into the vent. This plug has a vent small hole (about 1/8"). Can I assume this setup allows
proper ventilation and doesn't promote oil leakage?
Joe H

The one problem not mentioned in this thread is blow-by.
If your rings/culinders are worn, then excess combustion gasses blow by the pistons into the crancase raising the pressure above atmospheric, overcoming the effect of the breather tube and the vent to the air filters. Then oil is blown out everwhere it can get out, (rear seal, valve cover cap, valve cover seal, etc.). Then your engine is in need of a rebore to fix the leaks.
If you rocker bushings are badly worn, the the valve cover is flooded with oil, and you get leaks around the valve cover and cap, excess oil in the air filter, but no excess rear seal leak.
And of course if the rear main is worn, you get oil leaks at the rear seal, regardless of which seal you are using.
Leaks around the valve cover cap are most likely due to excess blow by.
Don Harmer

Mike, Denis, Don -- thanks for your suggestions and insights.

In my case I don't think valve cover leak and gas chamber cockpit are due to blowby; this is based on mileage, plugs, general performance, exhaust color, etc.

Mike, I agree that replacing the road draft tube with two little vents isn't a brilliant design. The reason I've been using that particular cover is that it's got a really big relief cast in its side for installing a magneto.

The mushroom plug for the valve cover breather used with some pancake air cleaner installations would seem to suffer from the same problem of spewing fumes into the engine bay.

I'm going to try a nitrile gasket and blocking off the vents on the tappet cover and plumbing it to the inlet manifold using a PCV valve. It should be possilbe to discretely snake the installation around the back.

Dave, didn't some of the smogged MGB's have PCV valves which would be about right. It seems morally wrong to put Pinto parts into Abingdon iron.

Thanks again.
Jack Williamson

Jack:

The MGB has a rather large and cumbersone valve which looks like a mushroom atop the inlet manifold. The Pinto unit is only about 3/4 - 1 in. in diameter, about 2 in. long, and would fit neatly in series with the flexible tube you plan to run around the back of the engine. True, the Pinto isn't genetic MG, but the 1600 Pinto has at least a British engine. These are the same basic blocks used in everything from English Ford to Cortinas to Lotus twin cams. Not exactly a mongrel pedigree!

Best regards,

Mike Brown,
Seven Shop British
Mike Brown

This thread was discussed between 18/02/2000 and 26/02/2000

MG TD TF 1500 index

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