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MG TD TF 1500 - PCV For a TD

All of this is from a thread on rebuilding a transmission that some of us inadvertantly hi-jacked so I'm putting it in a new thread.

Jud
B Roseberry, Colorado, USA
I've been offline for a while but I want to thank everyone for the great info and advice on my gearbox rebuild. Here's an update:
After discovering the laygear was pretty worn on the 1st gear, I pulled and tore down the gearbox in my parts car TD. I put together one good gearbox from the best parts of both. I also added the extra 1st gear selector rod detent and ball for more positive action. While it was out, I inverted the engine and redid the front seal w/ the Volvo unit and new cork seal at the rear. After reassembly and getting engine and gearbox back in the car, I added a PCV system from the tappet cover road tube to the intake manifold balance tube w/ a pinto PCV valve.
The gearbox now seems to work well and my pie plate oil puddle is now down to dime size or less.
Thanks again for all the great suggestions.
Bill


Posted 06 May 2014 at 03:43:03 UK time
Alex Waugh, Washington, USA, waugh.hoo@gmail.com
Bill,

I was thinking of you the other day. Thanks for the update and glad to hear you're back running again.

Alex


Posted 06 May 2014 at 11:19:09 UK time
Declan Burns, Germany, declan_burns@web.de
Bill,
Glad to hear that the PCV valve helped-it really does work as I have mentioned on here several times.
Regards
Declan

Image


Posted 06 May 2014 at 15:07:01 UK time
J K Chapin, South Carolina, USA
Declan, you picture fascinates me. I use three oil catch pans on the garage floor (big plastic storage bin tops) and although the quantity of oil loss is very small, it is always present when I bring the cart in from a run.

Am I correct in understanding that the tube shown in your pic going dwn from the flame trap is connected to the road tube in the tappet cover and that the pcv valve vents into the back of one of the air filters?

Also, is the cork in the valve cover vent tube holeless (i.e., no vent at all)?

Thanks.

Jud


Posted 06 May 2014 at 16:19:19 UK time
efh Haskell, Colorado, USA
Bill, hope to see it in person this Saturday.
Ed



Posted 06 May 2014 at 19:11:15 UK time
Declan Burns, Germany, declan_burns@web.de
Jud,
That is correct. The photo below shows it clearer. There is also a black rubber seal at the take off point on the tappet cover. The Pinto valve has two inlets one going to each side of the inlet manifold. The rubber bung has no hole and the oil filler has a similar but larger bung. Every source of infiltration air is sealed off as far as possible. The engine develops a vacuum at tick over which decreases with increasing revs. Air is drawn in through the leaky bits and where air is drawn in oil can't come out. It's that simple and it works. From a torrent to a trickle and a very cheap solution to an age old problem. It does upset the idle a bit.

Regards
Declan

Image


Posted 07 May 2014 at 10:58:57 UK time
Richard Cameron, Kentucky, USA
Very interesting on the PVC stuff. I sure would like to see more pictures of the side cover hose/ fitting attachment, and know if the road tube is actually closed off.


Posted 07 May 2014 at 11:41:12 UK time
Declan Burns, Germany, declan_burns@web.de
Richard,
There is no road tube. The side cover vent is plumbed directly to the flame trap. That engine side cover in the photo is actually from a Wolseley which I bought from Peter Edney in the UK. My car had an aftermarket Aluminium side cover which was not suitable for this mod but the standard TD cover can be used.It needs to be completely sealed.

Regards
Declan


Posted 09 May 2014 at 16:01:27 UK time
B Roseberry, Colorado, USA
Not to hi-jack this tranny thread, but a few people asked about the PCV system. Here are a couple of pictures.


Posted 09 May 2014 at 16:05:11 UK time
B Roseberry, Colorado, USA
Oops. No luck uploading my pictures. I'll try later.


Posted 13 May 2014 at 21:25:53 UK time
B Roseberry, Colorado, USA
I shrunk my files. Here's the PCV attachment to the tappet cover using a Pinto PCV valve.

Image


Posted 13 May 2014 at 21:29:04 UK time
B Roseberry, Colorado, USA
Here's where I tapped into the balance tube of the intake manifold. It was suggested to go from the valve cover to the intake manifold, but I was trying to make the plumbing less conspicuous. It also allowed me to keep the stock air cleaner configuration.

Image


Posted 13 May 2014 at 21:33:01 UK time
B Roseberry, Colorado, USA
The copper tube in the previous picture has nothing to do w/ the PCV system. It's part of an AMPCO top oiler.


Posted 14 May 2014 at 04:03:07 UK time
J K Chapin, South Carolina, USA
I guess I'm the hijack culprit for bing so interested in Declan's PCV setup but now the deed is done and I don't know how to move all the PCV messages into a new thread so I'll just press on and make matters worse with apologies to the group.

After looking at the PCV set up I was looking at the intake manifold on my TD and notice there is what appears to be about an 1/8" bung conveniently located on the top of the balance tube (see pic attached). I don't know if this is original or something a PO added but I'm wondering if it wouldn't be a good place to terminate a PCV setup similar to the ones shown by Declan and R. Roseberry?

Also, instead of tapping into the road vent tube, could one just clamp a hose to the end of the tube and use that as the starting point for a PCV system?

Thanks.

Jud

Image


Posted 14 May 2014 at 07:00:37 UK time
Declan Burns, Germany, declan_burns@web.de
Jud,
I'm also to blame on the highjacking of this thread.
It would be a good starting point but I would tap both sides of the manifold the next time you have it off just to be sure you have the right balance.

Just connect the road tube to the flame trap with a Piece of hose as a starting point and ensure that it is sealed.

How do we go about having the PCV discussion copied to a sepatate thread?

Regards
Declan


J K Chapin

I apologize for the utter newbieness of this, but what is a PCV valve? When someone said at the start of this thread that they had "added a PCV system from the tappet cover road tube to the intake manifold balance tube w/ a pinto PCV valve" I have to say I have no idea what that means...
Geoffrey M Baker

Positive Crankcase Ventilation... It's a product of the 60's... simple spring loaded one way valve designed to allow crankcase gases to be vented back into the intake system of the engine to be burnt again instead of simply escaping to the atmosphere...as with an XPAG vent tube.

in general terms ..it's open when the engine is under load and the carbs are pulling vacumn and closed when there is no vacumn present..such as when you let off the throttle. They are designed for the size of engine application and the placement in any given system.

The one from a Pinto should be a good choice..they came with 2000 and 2300 cc engines...might be a little over size...
MG LaVerne

Positive Crankcase Ventilation. It was (is?) one of the earliest pollution control devices. Someone better versed on the technology than I am can confirm but my understanding is that it sucks the oil and exhaust saturated gasses out of the crankcase and send them back into the cylinders where they are burned up and go out the tailpipe. Befoe PCV those gasses and the droplets of oil in them just vented down to the road.

Jud
J K Chapin

Positive Crankcase Ventilation. It was (is?) one of the earliest pollution control devices. Someone better versed on the technology than I am can confirm but my understanding is that it sucks the oil and exhaust saturated gasses out of the crankcase and send them back into the cylinders where they are burned up and go out the tailpipe. Befoe PCV those gasses and the droplets of oil in them just vented down to the road.

Jud

PS, I just realized that although I copied the text, the couple of images on the PCV thread didn't tag along. If someone years from now is looking for those images they will have to search for:
Thread: TD gearbox rebuild

Jud
J K Chapin

So the advantages is you don't leak oil as much and possibly get slightly improved mpg, but do you get decreased performance?
Geoffrey M Baker

Geoff - no better performance, but far better emissions control, required by law.

Tom Lange
t lange

Geoff,
FWIW
I had a lot of oil leaking also.
I looked into this after seeing some posts on here. The PCV valve is passive. It acts like a one way valve. The system is usually a loop. One end is attached to the vacuum of the intake manifold or air filter. The other end to the crankcase. The idea is to change the crankcase from positive to negative pressure. Instead of the positive pressure blowing oil past the seals the lower pressure either does not force anything out and can possibly suck in air thus preventing leaks.
The PCV valve is one way thus preventing any back-flow when the manifold or air filter is at positive pressure. In theory it sounded like a great way to reduce/prevent oil leaks.
There are many people with much more automotive experience than me that had opinions on this, both good and bad.
I decided that it was just treating a symptom and not the disease. I figured that I had a lot of blow by from the rings and that was causing high pressure in the crank. My solution was to overhaul the engine. I did it with the engine in the car. I found broken ring and damaged piston. New pistons and rings and cleaned up the cylinders. Put it back together and took great care with the gaskets and seals. Close to 1,000 miles and virtually no leaks.
I’m not saying you have the same exact situation but the bottom line for me is that this engine should not need a PCV system.
Mort
Mort 50 TD

Declan also posted: "The side cover vent is plumbed directly to the flame trap.:

What is a flame trap? Hw does it work? Is it essential? Where do you get one?

Thanks.

Jud
J K Chapin

Some good stuff about basic PVC systems in those paperbound Peterson/Hot Rod magazine books from the early days of smog control. I've got a 1978 one on carburetion that has a whole chapter it.

Apparently closed PVC systems had been used on commercial vehicles, milk trucks especially, which saw too little speed to make road draft effective.
kylemorley

Jud,
The flame trap is from a Land Rover discovery and is quite cheap. The source is below. The Wolseley side cover that I used also has an inbuilt flame trap so it's buckles and braces in my case as I could have got away without it. The photo shows the Wolseley side cover.
http://www.ebay.co.uk/itm/370618181945?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Regards
Declan


Declan Burns

Could someone Post a drawing of how to rig up the PVC valve etc, having trouble grasping it from the pic's posted.

Thanks


Regards

george
G Mills

George,
Here are two photos from John Quilter.
Mort


Mort 50 TD

Photo 2


Mort 50 TD

Here is the link to the thread they came from.
Mort


http://www2.mg-cars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=archiveth&subject=8&subjectar=8&thread=2012051315423815849
Mort 50 TD

George,
Here's the principle drawing. The U-tube is only used for setting up and then removed when sufficient vacuum crankkcase pressure had been reached.
Regards
Declan


Declan Burns

Round here, we call them U-tubes manometers.
kylemorley

Thank you all once again I am very appreciative , Declan your drawing is great I now know how it is fitted.

Regards

George


G Mills

This thread was discussed between 14/05/2014 and 17/05/2014

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.