MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Oil in Distributor

I don't know if this has come up before but as you can see I am having trouble with a lot of oil in my distributor.

I bought a reconditioned distributor from 123Ignition in the Netherlands and that distributor has this same problem.

I re-bushed my original distributor and installed it this weekend. The picture below is after about 100 miles.

How is it propagating into the distributor?

How do I stop it?

Do I have too much pressure in the crank case?

If so how do I measure it?

Your thoughts please.

Mort

Distributor
Type JE
Model 40162

Mort 50 TD

Mort - check the archives - "Oil Finding Its Way Into Distributor" ought to be the one.

Tom Lange
MGT Repair
t lange

Mort.
I seem to remember this cropping up before.
From what I remember there is a distributer from another egine that rotates the other way. There is a spiral cut on the shaft and it could pump up the oil.
It's possible you have two cases of the wrong shaft.
Maybe somebody got SHAFTED.
SANDY
Sandy

High crankcase pressure could be pushing oil uphill too.
MAndrus

Mort,
I also have oil in there,, even after it was rebuilt, supposedly from pressure in the crankcase,,(blow by ??) but you just did your rings last year IIRC, What you show is a lot of oil in only 100 miles,,,
The usual "band aid fix", is to drill a drain hole in the lower point of the dizzy bowl..
I don't remember any thing being posted about a dizzy that rotates the other way,,

Steve
SPW Wincze

Tom, Could not find anything in the archives. If anyone else can please direct me there.

Sandy, Below is a picture I took of the shaft threading. Since it is a right hand thread and it rotates ccw it should force the oil down.

Steve, I did new pistons and rings but with the engine in the car so the cylinders were not machined. I can't confirm the cylinder geometry. There well could be blow-by and excess pressure in the lower engine.

The car is running very well so perhaps a temporary fix of a drain hole is to be considered. I don't want to dump the oil straight out so I would attach a stub and run a hose to my oil drip pan.

Any other suggestions are most appreciated.

Mort

Mort 50 TD

Jeff at Advanced Distributors adds a third bushing to the shaft to prevent the problem you're having. He says it's a common problem. He rebuilt mine and it's working flawlessly.
Joe
Joe Olson

Mort - theswe should get you started:

"Oil finding way into distributor"

http://www2.mg-cars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=archiveth&subject=8&subjectar=8&thread=2008101300071810823

Also see "Oil in Distributor"

http://www2.mg-cars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=61559182100012&mode=archiveth&subject=8&subjectar=8&thread=200402010251414226
and

http://www2.mg-cars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=61559182100012&mode=archiveth&subject=early/96&subjectar=8&thread=E199810122111190

also "Distributor cap coated inside with oil"

http://www2.mg-cars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=61559182100012&mode=archiveth&subject=8&subjectar=8&thread=2013021116411623008

Also see "Dizzy awash in oil"

http://www2.mg-cars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=61559182100012&mode=archiveth&subject=8&subjectar=8&thread=2012081220040011641

Tom Lange
MGT Repair
t lange

Has the distributor shaft housing been drilled to half way between the 2 bushings, & a flat machined from this hole to the bottom of the shaft housing, for the oil to go back into the sump?
This was incorporated in later Lucas distributors.
Len Fanelli

Thanks Tom, I will review ASAP

Len, The unit from the Netherlands does not have that modification. My unit does as you can see below. It does not seem to be effective. Could it be that there is enough internal pressure in the lower engine to force oil up into the distributor through the groove and past the bushings (upper and lower)? Then the oil in the sump of the distributor just sits there since there is no pressure to push it down past the upper bushing.

Could a groove be put in the outer surface of the upper bushing to allow oil to drain down to the void between bushings then through the hole in the shaft then down the groove in the shaft to the sump?

If grooving that bushing is not practical then I thought of putting a small hose barb in the bottom area of the distributor and running tubing to my drip pan.

TIA,
Mort

Mort 50 TD

Come to think of it an extra groove in the upper bushing would just provide an even easier path for the oil to get into the distributor.

So far I have three viable solutions.

1-Thread a small hose barb into the bottom of the distributor housing and drain to oil drip pan.

2-Reduce the sump pressure. Reduce the blow-by and/or increase the venting.

3-Persue this quote from an old posting.
"Another solution to this oiling problem is the Butch Taras 'O' ring. An 'O' ring groove is machined into the body casting where the distributor shaft enters the body of the distributor. An 'O' ring fitted into this counterbore prevents the entry of oil into the body casting. Talk to Butch about the details of this'O' ring installation and his field experiences with this modification."

Anyone have an e-mail for Butch Taras?

Thanks,
Mort
Mort 50 TD

mgyowner@yahoo.com Good luck. Bud
Bud Krueger

Hope you manage to solve this one Mort. One more thing to look out for once I crank her up. Cheers
Peter TD 5801
P Hehir

Mort,
You have a supercharger fitted Right?

That may increase the sump pressure if your rings/ bore are a tad off.

I seem to remember your plumbing. Do you vent the tappet chest cover to outside or run it back to the carb along with the rocker box vent?

The tappet chest vent is larger so it may be better to just vent to atmosphere - maybe.

Not really sure how you set that up. You are using Tom's great rubber caskets as well right?

Just a thought.

Rod

PS Did you do a compression test yet?
R. D. Jones

PLEASE - I do NOT sell MG caskets, for those who are concerned. Although if I get enough requests...

LOL Tom Lange
MGT Repair
t lange

:)

Love that auto spell checker.

Tom, I think the wife had already decide to bury me in the TD.

The only real question is :

"When"

R. D. Jones

Thank you Rod for the thoughts.

R. D. Jones, Maine, USA

Mort,
You have a supercharger fitted Right? YES

That may increase the sump pressure if your rings/ bore are a tad off. EXACTLY

I seem to remember your plumbing. Do you vent the tappet chest cover to outside or run it back to the carb along with the rocker box vent? THEY BOTH TEE IN TO A SMALL OIL SCRUBBER THEN INTO THE INTAKE OF THE CARB.

The tappet chest vent is larger so it may be better to just vent to atmosphere - maybe. I STOPPED VENTING THE SIDE COVER TO ATMOSPHERE BECAUSE OF THE MESS IT MAKES UNDER THE CAR.

THE ATMOSPHERE IN THE CARB air filter WHERE THE EXHAUSTS VENT TO SHOULD BE ALWAYS UNDER VACUUM SINCE THE CARB WANTS AIR AS SOON AS THE ENGINE IS RUNNING. I WOULD THINK THAT WOULD DRAW DOWN THE PRESSURE IN THE ENGINE COMPARTMENTS FASTER THAN VENTING TO ATMOSPHERE.

Not really sure how you set that up. You are using Tom's great rubber caskets as well right? SILICONE GASKETS, YEP! VALVE AND SIDE COVERS

Just a thought.

Rod

PS Did you do a compression test yet? NOT RECENTLY BUT IT IS NOW ON THE SCHEDULE
Mort 50 TD

Photo of venting

Mort 50 TD

Another view

Mort 50 TD

Mort - e-mail me at SUfuelpumps@donobi.net and I'll send you an article regarding the distributor oiling problem and how to fix it. Cheers - Dave
DW DuBois

Photo of scrubber leading to the back of the air filter. There is a little coarse steel wool in the chamber to precipitate out some of the oil in the exhaust fumes.

The scrubber is on a slant so if the chamber gets filled enough with oil it runs back down the tubing into the side cover.

Mort 50 TD

Have you done a leakdown test?
mog

Thanks Dave. Useful article if only to show that this is not a new problem. It seems Mort's dizzy already has the mod Carl proposes so perhaps the O ring suggested by Butch is the way to go. Not sure how you would go about cutting the O ring seat though.. Cheers
Peter TD 5801
P Hehir

I have e-mailed Butch Taras and the o-ring was just an idea. Never actually done.
So I was thinking about it and need a sanity check here.

First...I hope my sketch is correct.

Second...Where would the o-ring go? The oil entry path to the distributor is between the bushings and the rotating shaft. The groove for the o-ring would have to be in the bushing or the shaft. I think the bushing is too thin so it would be in the shaft. Easier to machine also.

Third...Lets assume the fit was good enough to prevent oil from propagating into the distributor body. This is a high speed rotating shaft. Wouldn't the o-ring just wear down and start leaking?

Fourth...Could the upper bushing be shortened and a seal put in above it? (I'll try to sketch that)

Mort

Mort 50 TD

with o-ring

Mort 50 TD

With Seal

Mort 50 TD

Mort, any chance that you could slip a pressure measuring device into the dipstick hole and see what sort of pressure we're talking about? Bud
Bud Krueger

Mort,
Make up a U-tube manometer as shown below and connect it to the dipstick hole. It is very easy to do. 10mm difference (A-B)in the water level=1mbar pressure. This will tell you if you have positive or negative crankcase pressure. If you fit a PCV valve you will certainly induce negative crankcase pressure and it will reduce the oil leaks but at the cost of upsetting the idle. I found that inserting a 1.7mm restrictor in the line from the tapping point at the inlet manifold to the PCV valve was ideal-from a torrent to a trickle!

Regards
Declan

D Burns

After looking at your sketches, I don't see where a third bushing would fit, but FWIW here's what Jeff Zorn wrote to me about my newly rebuilt unit:

"I set the shaft clearance very tight on that distributor because the engine tends to pump oil up the shaft into the distributor. By adding a third shaft bushing where there previously wasn't one, there is a tight area on unworn shaft that needs to be polished out to rotate smoothly."

He'd be the first guy I would ask if my unit started to leak.

Joe
Joe Olson

The other thing that can cause excessive oil in the distributor is the amount of end float between the distributor body and the drive gear. If this is excessive, the camshaft, by repeatedly slowing and speeding up, can cause slight upward and downward movement of the distributor shaft. This can act as a pump pulling oil up the shaft. The end float should be around 0.010" or so and can be set by a washer between the body and the drive gear. Of course, if the bushings are not worn and there is minimal clearance, this is not an issue.
LD Palmer

Ld the end float spec from Lucas is .002. This was originally set when the bottom washer was put on it had three dimples, you put the gear on pined it then hit the bottom of the shaft with a hammer compressing the dimples to give the clearance. Also most of the time the plastic washer under the advance plate is worn out. I am working on a sample dizzy with a seal. I'll let everyone know when I get it done and tested.

Butch
R Taras

Butch I read somewhere that the bottom washer above the spiral gear was a wave washer, the idea being that it would constantly apply some pressure to the gear ensuring good contact with the cam yet still allowing the specified clearance. If so this would help counteract the pumping action Lew describes & presumably minimize the ingress of oil. Cheers
Peter TD 5801
P Hehir

Hello Peter. When I rebuild the dizzys I machine a new washer for under the advance plate, put it back together and measure the distance from the shank to the gear and turn a spacer that gives the correct clearance. I've never seen a wave washer on the distributor most of the time they are phenolic and crack when you disassemble the gear. A wave spring washer would sit flat enough to block ingress of oil. The shaft is .489 dia. or 12.4mm which is an odd size to find a washer for.

Butch
R Taras

There is another path for oil to escape as shown below. I understand that keeping a tight fit with the proper thickness washer will minimize it, but for those of us with a little more crankcase pressure (S/C) oil does come up and into the engine compartment.

I was thinking about a smear of Permatex on both faces of the clamping ring and a glop at the opening. Then install and time the advance quickly before it sets. I know the next time you need to loosen the clamp you will have to break the seal, clean it and start over.

A good solution to this path would be an o-ring. Not to difficult to cut this o-ring groove.

Anyone have a better idea?

Mort

Mort 50 TD

Declan is definitely on the correct track with resolving this issue if the clearances between the distributor shaft and bushings are correct. The original design of these engines was to vent the sump via the side plate drain.

The plumbing of a PCV has to be carefully designed to achieve the same effect. My opinion is that once you supercharge an engine the operation of a PCV is compromised because you are creating a positive pressure in the induction manifold and would be reliant on the fuel/air flow venturi action past the PCV tapping to create a negative pressure in the sump.

This is applicable, once you interfere with the original design concepts of any engine you have to be aware there will be ramifications that require careful consideration.
G Evans

Mort, Your problem with oil in the distributor is obviously excessive blow-by. Obviously the best solution is properly rebuild the engine (boar the cylinders, install new rings, etc.). A properly rebuilt engine will have very little blow-by. Aside from that, the rudimentary pcv system you have engineered obviously is not sufficient. you stated that you abandoned the draft tube because it made a mess. I am not familiar with the silicone roadster gaskets, but have never had a problem the cork ones. They are designed with a wet side/dry side, and should prevent oil latent air from exiting the draft tube. I have worked on the XPAG engines that had rubber gaskets installed for the side cover which deformed, became sloppy, and obstructed the flow of air through the draft tube. Originally, as designed the draft tube had 4 little standoffs to prevent the gasket from sealing its opening. I would warm the engine, remove the oil filler cap and see what kind of air flow you are getting. Then disconnect your entire breathing system, plug the vent from the valve cover and see what you are getting out of the side cover with the oil filler in place. The side cover vent should be your main route of venting crank case pressure. Search the archives. I remember a post from a gent who had a similar problem who made some type of an oil trap to vent the engine without a mess.

If you have any questions or if I can be of any additional help, call me.

Gregory S.
Columbia Restorations
(708) 715-5517
GMS Serduke

Greg,
I have to say I think the Tappet Chest gasket form Tom Lang is far superior than the older original cork/rubber one.
It has the same design of holes to help baffle the oil mist form going strait out the vent tube. It will not squish out or collapse and seals the cover perfectly with less tension in the 3 nuts. If the Vent Tube is secured at the bottom of the bell housing it will only drop said oil to the under side of the car and help it not to rust. If Mort has a bore and ring issue causing blow-by the oil loss could be more than desirable. But should not cover the engine with oil. The vent tube to the carbs was designed to go to the air filter to presumably assist in removing the crank case pressure some. They did fit a restrictor to this to help prevent excessive oil burn.
I don't think Superchargers were the normal fit and will possibly cause other issues not normally seen with a STD engine set up. That said with rings and bores in good condition Mort may no longer have this issue.
A compression test or leakdown test would give a good indication as to what is going on.
The distributor in good condition and low crank pressure does not seem to have a problem. My engine is far form tight and it has been a long tome since it was worked on. but I do not have oil in the dissy.
Just my 2c worth.

Good luck Mort solving this issue. I am sure you will resolve it.

Rod
R. D. Jones

Following some of the above suggestions I connected a pressure/vacuum gauge to the dip stick stub.
Took it for a drive under different loading conditions.

I previously had this gauge connected to the manifold between the supercharger and the engine intake ports. My dash board gauge and this gauge coordinated perfectly.

Under full load of 4-1/2 to 5 pounds of boost the needle barely moved to just under a 1/2 pound of pressure. When my manifold was under 30 inches of mercury vacuum, I could get no reading from the crankcase.

Does anyone know what the crankcase pressure should be?


TIA,
Mort


Mort 50 TD

I know I am treating the symptom instead of the disease but I provided a port for oil to drain out of the distributor.
The tubing goes down to another barb in the oil drip pan.
I wanted the barb to be closer to the lowest point but it interfered with the shoulder bolt.

Mort 50 TD

Mort,
With that gauge you will not be able to measure it accurately. When I fitted the PCV valve I measured -12mbar (-0.354 in Hg) at idle with the U-tube manometer as shown in my drawing further up. This would hardly show on your gauge. I have since fitted a 1.7mm restrictor between inlet manifold and PCV valve to improve the idle but have not checked the gauge which I suspect would now read somewhere between -8mbar (-0.23in Hg) and -5mbar (0.14 in Hg). The main thing is that it is negative. I can measure it over the weekend if you want.

Regards
Declan
D Burns

Mort,
Just to add:
This is the standard method of checking pressures in industrial pipelines/ducting and we have been using this method for decades in industry. Simple cheap physics. You only need a small bore clear plastic tube from the DIY fixed on a wooden backing plate, a ruler and water. Put some plasticine around the tube where it enters the dipstick hole and measure the difference in water levels. You will soon find out if you have too high positive crankcase pressure as it will blow the water out of the gauge.

Regards
Declan
D Burns

Dm type dizzy shaft, easy enough to mod a dka to the same profile, note spiral is much more substantial to the early version. Cut away section of the shaft should reduce wicking/pumping of oil.

mog

Mort,

In your opening description you mentioned thet the distributor is a model 40162. however looking at the attached picture I see that the advance mechanism does not correspond to this model. It looks as if the shaft/plate assembly has been replaced with somthing else. If so then you need to take a careful look at the shaft, check the diameter, length and spiral direction. I don't recognize the mechanism, it may not even be Lucas.


John
J Scragg

John,
The dizzy label says 40162 but after 65 years and who knows how many owners the guts could be anything. The saving grace is that I sent it to Jeff at Advanced (see label on the dizzy) and he did a complete rebuild for the TD.
The shaft, diameter, spiral and length all check out OK.

Declan,
As time permits I will make a manometer.

Thanks,
Mort
Mort 50 TD

Normally you guys are so helpful, why did you do this to my car?

I've been following this thread not that it was a concern just learning.
Took the car out today to go to the store 5 miles from home.
Pulled into the parking lot and all of a sudden the car lost power.
Could only get the car to run with full throttle at about 200 hundred RPMs, yes 200 not 2000. Started checking everything, fuel, wires, carbs, etc.
I pulled the dizzy cap. Oil dripped down the side! It was full of oil !
Took everything apart and some paper towels to clean up all the oil.
Put it back together and the car started right up and idled as sweet as could be. I did try starting after each item was fooled with so it was the oil fowling the distributor.
When I got home there was more oil in the dizzies base :(
How did you guys do that over the internet, my car has not ever been near my computer!
G D

G.D.
This is the same phenomenon as the Murray Walker "Commentators Curse"

The leader was on the last lap - 2 laps ahead, and he said " There is no way he can loose this one now"

At which point the engine blew up...

Of cause everyone knew it was Murray's fault.

:)

Hope you can resolve the issue.
Have you done a compression test?
Could have lost a ring and the sump pressure could suddenly have increased? Hope not.

Rod

R. D. Jones

This thread was discussed between 29/06/2015 and 12/07/2015

MG TD TF 1500 index

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