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MG TD TF 1500 - Valve Cover Spitting

Ever since I reset my tappets from .015 to .019" I have noticed a lot of oil being sprayed out of the center relief. I am not sure the two are related. It is mostly visible on the valve cover around the relief.
I seem to recall a previous posting on this but can not find it.
Any suggestions are most welcome.
Mort


Mort Resnicoff (50 TD-Mobius)

Mort,
Based on the picture, your valve cover doesn't seem to be vented. Without a vent, excess pressure can cause the "spitting". Normally, the vent pipe in the center of the valve cover is connected to the air cleaner thus recirculating oil vapor into the carb and easing the pressure build up.
Lew Palmer

Heck. He doesn't even have a distributor or 3 spark plug wires so I doubt that's his problem. Perhaps the car is just sarcastic :-)
Chris Couper

Is the center thing a vent or plug? Similar problem with a TF in the area with very similar VC, and "vent plug" in breather hole. Had to fabricate and have welded a splash shield inside the cover over the internal opening. With your supercharger of course you can't connect to your air cleaner. George
George Butz

If your "relief" isn't completely sealed off, expect oil mist. I ran ours to the supercharger air cleaner, but oil dripped out the bottom by the nature of the design. Our rocker shaft is completely covered by an extra aluminum baffle/shield, but that couldn't eliminate the mist. I finally just completely sealed it off. The original oil bath air cleaner won't have this problem.

The "road draft tube" ought to vent internal pressure, as long as the gasket for the sidecover has vent holes.

Valve lash won't have any influence on the oil exodus.

When you have the "coffin" valve cover off, inspect it inside for marks from the valves hitting it! It can sound like a knock, too. I ground the heck out of ours and shove it over before tightening it down, but, it has a mind of its own and, in time, wanders back to the valves.


JIM NORTHRUP SR

I'm pretty sure you need both top and bottom venting but I'd sure like to hear from folks knowledgeable.

Jud


J K Chapin

jud, interesting anchor point for your filler cap. i have not seen that before.
i would not close mine off, but i think the side cover would give adequate venting..there was an early mod to these valve cover vent pipes..it involved reducing the opening of the vent pipe by welding a plug in the end then drilling a small hole in the plug. i do not remember the hole size.


regards, tom
tom peterson

Tom - I believe that the restrictor is disk was placed in the spigot on the oil bath air cleaner - that is where it is on our TD and I remember seeing something about it in a service bulletin. Cheers - Dave
David DuBois

Y'all are making me wonder if I need to put some kind of restrictor (plug with a small hole) under my Xmas tree filter. The filter does get oily but not so much that it oozes. Thoughts?

Thanks.

Jud
J K Chapin

Sorry folks. I used an old picture of the valve cover. Below is the current picture. The next post is a close up of the vent.
The set screw holds it in place so that the 4 small holes remain exposed. That is where the oil is coming from.

Jim and Jud,
I had a small K & N filter on the valve cover but it would just collect enough oil and then spill over onto the valve cover. Piping it to the air filter at the carb would be the same problem.

I know my side breather pipe is functioning because it always leaves an oil drip. I've been told that when I accelerate hard people can see smoke coming out of the breather pipe. I put an extension on the breather pipe to keep the oil off the frame and engine compartment.

Would there be a problem just to seal off the top stub on the valve cover?




Mort Resnicoff (50 TD-Mobius)

valve cover vent.


Mort Resnicoff (50 TD-Mobius)

One thing you might want to look at is a baffle. One the original valve cover there is a vented plate that covers the breather hole. This keeps the oil from being sprayed into the hole but allows the pressure to be vented.
Chris Couper

I do recall an old post from a couple of years ago about an internal baffle or an internal plate to hold up some heavy steel wool that acted as a baffle.

That is the post I am trying to find.

Mort
Mort Resnicoff (50 TD-Mobius)

I'm told that the original style valve cover has a baffle for that purpose. I haven't removed mine yet but plan on doing it soon to paint it semi-gloss grey at which time I'll take a look and post a picture of the inside.

Mort, my TD came to me with a solid rubber plug in the upper vent pipe. Several mechanics including Hal Waldrop told me I needed the top vent, ergo the Xmas tree from K&N. Don't fully understand why a closed system needs to be vented at all (when one piston is down another one is up so the net internal volume should stay the same or so it seems to me) but I defer to their superior knowledge.

Jud
J K Chapin

Mud,
The crankcase needs to be vented. Rings are not perfect and allows blow-by, which pressurized the crankcase. It is not about internal piston movement.

If not vented, you will leak oil out of the bearings and gaskets, or will find the oil cap popped off.

This is true in today's vehicles, they now call it a PCV valve. I think MG and SU were actually leaders in recirculating the crankcase gasses, it did not come to many cars until the later 50's.

Dean E

Can anyone explain the need for a top vent if the side vents properly?

Mort
Mort Resnicoff (50 TD-Mobius)

Top vent provides another port to emit oil vapor!

There are 4 principle vents of oil-
valve cover, front main seal, rear main seal and side cover.

If these 4 vents plug up, the engine will explode, justifying Homeland Security (explaitive deleted).
JIM NORTHRUP SR

another source of pressure, if the valve cover is sealed tightly, is valve stem leakage.
If, perchance, you have one tappet just a bit too tight so its not seated on compression stroke and pressure leaks past, even on one valve, even on part of the stroke , you can cause this.

I would first reset your clearance. then if the problem is still there add 0.001" of additional clearance.


Just a pepper tree mechanic

Jim B
JA Benjamin

Mort , just curious :..WHY have you reset the tappets in the beginning.

Thanks for your time,

Gerard
Gerard Hengeveld

Gerard,
I have no specs on the cam that came with the car. In trying to resolve the intermittent loss of power and backfiring, Jim Northrop suggested the .019" clearance. He also has a supercharger.
Mort
Mort Resnicoff (50 TD-Mobius)

Dean:
"Mud,
The crankcase needs to be vented."

Was it something I said? :-)

Jud

Thanks to all for the explanation of increasing pressure in the crankcase. Makes perfect sense in an imperfect world.

Jud
J K Chapin

Mort,
"I do recall an old post from a couple of years ago about an internal baffle or an internal plate to hold up some heavy steel wool that acted as a baffle.
That is the post I am trying to find."

I seem to have no luck finding things in the archives!
I looked for some time last night for this one.

I contributed with pictures of the baffle's I made ...but those were lost to a hard drive crash so I no longer have them.

I think LaVern started the thread with some info on stopping leaks from aftermarket tappet covers?

Darned if I can find it!
I'll keep looking!
David Sheward

Mort,
Reactivated an old thread for you...not quite the one I was looking for though.

The valve cover vent you show above is very similar to the one I used on my TF. (After market V/C and Vokes air cleaners)

I ended up grinding it down and installing "inside" the V/C as a baffle, then ran pipe to my front air cleaner per original on the TF. Without the baffle my front air cleaner was getting soaked with oil @ hi RPM'S.

Do you have a stock valve cover? If yes ...you can see how it was baffled, if not let me know and I can get a pic of one for you. None of the aftermarket ones I have had over the years had the baffle. Most were vented with similar to what you show...but still "dripped" a bit @ hi RPM.
David Sheward

Stock valve cover baffle. TF style (side discharge..TD was on top.)


David Sheward

Do you mean this from John Twist via gordon lawson as in Ttalk-http://www.ttalk.info/picture_this.htm#Oil%20Deflector ? Bud
Bud Krueger

When you get there, just scan down to 'Oil Deflector' and click on it. Bud
Bud Krueger

Bud,
Having trouble with your site. Finally got to home page and went round about to picture this. Now I can see the text but not the images. Can you e-mail me the image?
Thanks,
Mort
Mort Resnicoff (50 TD-Mobius)

Here are the images (3 of them):
Image1:


Bud Krueger

Image2:


Bud Krueger

Deflector3:


Bud Krueger

This thread was discussed between 04/11/2013 and 07/11/2013

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