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MG TD TF 1500 - Stopping the oil leak on the Moss tappet cover

Last years 10000 miles of driving the Green Hornet found me losing about a quart of oil every 1000 miles. The TF underside looked like the Exon Valdez. It was obvious that oil was escaping from the aftermarket alloy side cover vents among other places?

This is the tappet cover I'm referring to.

The vents do not contain any sort of baffle from the package.


One thing I noticed when removing the cover, is that the gasket showed rub marks from the push rods. My thinking is that it would be acting as a wiper and perhaps taking valuable oil flow away from the tappets. Also by design it would appear that the gasket itself would become a catch basin for the oil, only spilling when it reached the openings farther up the gasket instead of draining back to the sump. I figure it has a better chance of not leaking at the bottom of the gasket if it can flow back to the sump. Can I prove those theories? No, but I chose to remove the center of the gasket and use it as a traditional flange type gasket. I coated the gasket with some gray Permatex and stuck it to the tappet cover.
As for the vent covers, they are held in place with two screws each. I removed the covers and packed the full with some stainless steel scrub material ( see photo) found at my local hardware store. Then I covered the opening with some aluminum window screen ( also picked up at the hardware store). Finally I gave the mounting surface a ribbon of the gray Permatex and mounted the vents back to the tappet cover and then on the engine.


After some road testing I was disappointed to find that while the mesh had slowed down the flow it did not stop it as evidenced by two lines running down from the vents. So off she came and I came to the conclusion that what was needed was a baffle. I found some old brackets in my stuff that I believe came with some outdoor speakers years ago. I'm including some pictures so you can get the idea of what is needed. The idea here is to prevent direct flow of the oil to the vents yet still allow them to breath.

The bracket


The length for each vent I used by cutting a piece from each end.


the width


And the profile. I ground one of the flange edges off the bracket and drilled two holes for the screw mounts. After mounting it was clear that there was still an opening at the top of the casting that would provide direct flow. I sealed up this opening with some gray Permatex.

I am very pleased to report that this has stopped all the leaks ( at least at this point) from the tappet cover. In addition I find that the nifty catch can I made for the rear of the engine although very functional was unneeded. The motor is bone dry after about 40 miles of driving.

Yee haw.

The original gasket was meant to act as a baffle, and had drain holes at the lower corners. I well recall the first time I took one of these off and spent a lot of time figuring out why they didn't cut the center out and use the material for other gaskets.
For all those pictures, you gave me nothing to show what the vents are actually like, or what your cure looks like! Back in the 60's there was a considerable industry in aftermarket vents that vented but did not let (or force) all the oil out. These must be one of the poorer types.
Anyway, congrats on dry motor - now you have to worry about rust!

FR Millmore

LaVerne, I have the same cover as you but was able to get a gasket from Roadster Gaskets,it is neoprene and is great. Unfortunatly they are now out of business.
Tom Maine (TD8105)

Sorry Fletch I didn't take any pictures of the install. Somebody else asked about my cure. As for the original, it does have the lower drain holes but they aren't low enough to prevent a resevoir from building. My uneducated guess was that the full gasket was used to locate it's position on the block without any adhesives. And yes the cover is a cheap made knock off cast in China.

I should add I suppose, that the upper gasket holes are in a direct line with the vents. An easier fix might have been to just cut a new gasket and move the openings from that direct line. But since I had a couple of tappet gaskets lying here I went with what came to my head first.

WSM Sec A24:
"Care should be taken when refitting the side cover to see that the drain holes in its gasket are at the bottom."
So, is repro-screwt the same as first order screwt?

FR Millmore

My tappet cover has one vent in the upper center of the cover and no vent pipe as in the standard cover. I took a kitchen scrubber (Scotch) which is green in color and about 1/4" thick. I cut it to fit the vent opening (in width) and kept it long enough so that I could fold it and stick it in the opening. My thinking is that it would hold OK and slow any oil leakage. I only have perhaps 10 miles on the car and thusfar no leaks. The car is in the shop getting new interior installed so I am unable to upload a current photo.
David DuBois

Yo Larry K. I think that you are showing up as me again, probably due to the link that I sent you. Cheers - Dave
David DuBois

Thanks for posting this one. I have the same cover and the same "leaks". Very simular cure that I had tried with my after-market valve cover. (baffle & wadding). My tappet cover is off right now so going to give this a shot.

Did not know Roadster Gaskets neoprene are now NA. (Glad a bought an extra set!) That did help considerably over the cork gasket that was on there before but still had some "drip lines" after running the engine hard. ("Hard" is how I like to drive the TF!) Didn't have very good luck with any gasket (cork or neoprene) on my after-market valve cover. Ended up making a cork one that fit the cover.

Anybody know a source for "sheet neoprene"?
Was thinking about cutting one for the valve cover to replace the cork one I had made 10 years ago this time.
David Sheward

Try McMaster-Carr. Enter "neoprene sheet" in their search engine. There seems to be a great deal of reasonable priced pieces in there.
Mort 50TD (1851) Mobius

Interesting note from the Workshop Manual Fletch. It would be my guess that the original gaskets had only one set of vent openings verses the "twin mirrors" that we have today. Admittingly, what the full gasket catches wouldn't be much but why give it the opportunity. I might have been better to have just left the stock cover on but the alloy cover came with the purchase of the TD and I figured it matched the valve cover so on she went.


Thanks Mort,
Nice site.
Looks like I will be making some new gaskets.
Been working a bunch lately but have a couple days off comming up. Good time to drag out my "collection" of old gaskets and do some comparisons.

(Yeah ...I know "who saves old gaskets?" ... Me!
Come in handy as templets.)

Pretty sure I have at least 3 different styles of tappet & valve cover ones. I'll post up some pics if I find some interesting "differances". Think I have an old NOS set that are way too brittle to use, but seem to recall they are "sized" considerably different than some of the replacements sold today.
David Sheward

Next question:
How much "air-flow" does one need in there?
Vents are stuffed with "copper scrubby", and I have about an 1/8" "gap" at the bottom.
Looks like the gap at top will be mostly covered by the gasket.

David Sheward

That's kinda what I did David. Except with the channeled material I was working with, it could breath from the sides. I filled the openings on top with some gray Peramtex. Also put in screen between the vent housing and the cover to make sure the fill material didn't find it's way to the crank case and a seal of the permatex when I screwed them in place. Not sure about allowing the vent direction from the bottom of your baffle. Way mine are set up it has to travel sideways and up to escape. So far....knock on your left's working great.

Suddenly it hit the wet slap at the end of a cold fist.
Back to the drawing board tomorrow to find a more suitable piece!
David Sheward

I see I missed a picture David. Not a great pic but it's roughly a 1/4" depth. As I said, I ground off the flange on one side and that's the side I put to the top. I started out shaping it to try and cover the upper gap you show in your photo but it wasn't goining to work for me so I just took it all off and sealed that opening with the goo.


Round two:
Much better today.
One on, one "in progress" in this shot.
Did the same as you at the top.

David Sheward

Looks like the ticket to me David. Only addition I'd make is the window screen between the vent and the cover to make sure the fill material doesn't somehow find it's way back into the sump. I cut pieces to shape and set them over the vent. Poke two screw holes in it and a bead of the permatex and screwed it down. wipe off the excess permatex and nobody is the wiser.

Oops ...did that (screen) but left it out of the picture. Was trying to get everything in one shot for Fletch.
Should find out soon if it did the trick...still cleaning all the old oil off so I will be able to tell.

Put some wadding & screen in my valve cover vent to air filter also since I am going to try the Volks on it this time. Hoping that will slow the "flow" a bit to my new K&H filters.

Somebody needs to breed some kind of little creature that laps up oil...I'm a mess.
David Sheward

Test run results:
Tappet cover: Dry / no leaks or seeping from vents.

Valve Cover: Dismal failiure.
Decided to try one of the Nitrile Rubber gaskets I had (instead of 10 year old cork one I made last time). I run an after market cover and the Nitrile gasket (as well as cork ones) is just a bit "too small". Dumb as the "paper" with the NG states "for stock cover only...should have 1/16" overhang".

I found this on Amazon and will cut a gasket from it... after I clean up the oil that leaked out the front of the VC.

I have some concern if this is "soft enough" from the description...but figured it was worth a shot at that price.
Will report back.
David Sheward

Found it!
(For reactivation)
David Sheward

David, I have that same cover and use the Roadster Gasket on it. Tom Lange has them.
Tom Maine (TD8105)

Roadster Gasket is fine on Tappet cover, (although I made one for it out of material I bought ..1/16").
My problem was the "older version" did not fit my aftermarket Valve cover. (It's a bit oversized compaired to stock.)

Tom sent me one (VC) to try ...but have been so busy with work I have not had time to take the one I made for valve cover off and try the one Tom sent me.

Hoping to get some time to do that soon so I can report back to him.
David Sheward

David Sheward

reactive this thread
David Sheward 55 TF1500 # 7427

Thanks David. Way to go. Rather than suggest (as others often do) that a search of the archives is called for, your solution of reactivating the appropriate thread is far & away the most helpful way of enabling the enquirer to proceed. This should get you sorted Larry. Cheers
Peter TD 5801
P Hehir

This thread was discussed between 09/03/2012 and 20/07/2014

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