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MG TD TF 1500 - Oil in the distributor

What could be causing a bit of oil to get into the distributor of my 1952 TDC? What would be the fix?
EB Blackwelder

From a Tom Lange post in the archives:
"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

As Tom mentioned when he first researched it...this should get you started.

Gene
Gene Gillam

Gene
Super, nice job of putting everything together in one posting !! Do you have saved somewhere so it can be copied and pasted for future use ??

Steve
Steve Wincze

The oil paths between the sump and the distributor are limited.I am not an expert but from my limited experience there are two general causes.

The first is the physical relationship between the various distributor stem parts. Are the bushings worn? Has the shaft been modified to allow the oil to flow back down?

The second is excessive pressure in the crankcase. This is usually due to blow by. If this is the case there may be nothing wrong with the distributor. The pressure is just forcing the oil up the shaft. Do you have excessive oil leaks in other areas?

Also check the archives. Lots of articles about this.

Mort
Mort 50 TD

This has been a long time problem for as long as I can remember on the earlier TDs. Since our TD is a late 53, we never had this problem and I could never figure out why others had this particular problem while I didn't. This was back in the BC (before computers) and all of the various clubs had written newsletters, some better than others. One group that had an excellent newsletter was the Southern California Vintage MG Club and one of their members, Carl Cederstrand was a prolific writter. Carl wrote an article "Distributors That Drown in Oil" Below is a copy of that particular article, along with a drawing that he included. Cheers - Dave

Distributors That Drown in Oil by Carl Cederstrand

The Archimedean screw pump is an ancient machine attributed to Archimedes. These pumps have been used in the Near East for lifting irrigation water for more than two thousand years. They consist of a spiral passage (groove) cut into an enclosed rotating cylinder. The wiping of the entrained liquid by the spiral wall of the groove drags the liquid from one end on the screw to the other. Mr. Archmedes' pumps are low pressure low volume pumps. Their advantage is that they consist of a single moving part - a rotating cylinder.

The two Archimedean Screw Pumps incorporated in our T-Series engines are used to control oil. The first one, on the rear of the crankshaft, continually pumps errant oil back into the engine. The second one, on the distributor shaft, continually pumps oil back into the sump. Unfortunately neither of these Archimedean pumps work reliably. Many T-Series engines dribble oil from their rear crankshaft 'seals' and fill their distributors with oil. Oh me!

This is how I eventually dispatched the problem of oil accumulating in the distributor. As John Seim pointed out at the May club meeting, Lucas added drain holes in the bottom of their distributor castings to drain off any accumulated oil. The oil drain(s) worked satisfactorly and in doing so poured oil down the left side of the engine. I drilled my distributor casting and accomplished the same result. The drain hole worked to a degree but it was an inadequate solution to the oiling problem. My distributor points still drowned in oil and the oil honeying down the left side of the engine bothered me. A length of 1/8" diameter tygon tubing was later added to connected the distributor drain hole to a hole drilled in the side of the dip stick tube. This kept the block tidy. My conclusion was that the drain hole reduced the degree of oiling and slowed down the rate of oiling. It didn't stop it.

The next modification put this problem to bed 'in perpetuity'. Forget about that 'Mickey Mouse' drain hole in the distributor. Instead, add a hole and slot to the pipe cast into the bottom of the distributor. Inspect the included drawing. The added hole and slot provides an, in the block, drainage system for the oil being pumped upward into the distributor body. Oil exits through the internal drain hole and then drains down the slot and back into the sump. It never reaches the distributor casting. This system works - cheers! This hole and slot may be incorporated in any T-Series distributor. The VMG contains club members with machine shops, both commercial and home, that can tend to distributor modifications for you. I originally observed this hole and slot system in a Lucas distributor that had been forwarded to Jerry Felper for rebuilding.

I also had Phil Marino turn out a 'one of a kind' aluminum-bronze thrust washer for fitting between the drive gear and the end of the distributor. Both the drive gear and the distributor end were lapped smooth on a surface plate. This thrust washer controls the end float in the distributor shaft. Its thickness was adjusted to provide the 0.002" end float that Lucas recommends. Tight control of the end float of the distributor shaft reduces the rate of oil pumping. It cannot stop it.

My, now dry, distributor housing has a disadvantage. The elimination of the accumulating oil requires that I remember to lubricate the upper distributor bearing. Oiling this upper bearing (bronze bushing) is accomplished through the center drilled screw hidden under the distributor rotor.

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.

For decades I casually viewed the Archimedian spiral cut into the distributor shaft and blithely assumed that it was responsible for pumping oil up into the distributor body. After all, how otherwise could so much oil end up in the distributor casting? Well, I was totally wrong. I have onlv now taken note of the direction of the Archimedean spiral and, "Good grief Charlie Brown", the spiral is cut in that direction to pump oil down and out from the distributor. Forget the hare brained idea that the Archimedian screw forces oil up into the distributor body - it doesn't. Since an oil pumping mechanism obviously exists, let me propose the following physical picture for review by the MG gurus in the VMG.

The oil pumping is probably due to capillary movement of oil up through the lower bearing followed by centrifugal oil slinging. The centrifugal slinging of oil by the rotating distributor shaft (say, 2000 rpm) serves as a very primitive centrifugal pump. The annular space between the two distributor bushings eventually contains a rotating cylindrical shell of oil - what a nice thought! This primitive centrifugal pump spreads oil up toward the distributor body and evidently overwhelms the even more primitive Archimedian screw pump that is attempting to pump oil down toward the drive gear.

As a concluding thought, the pressure of rotating oil against the inner wall of the pipe may very well be the reason the drain hole and slot system works so well. If anyone has words of wisdom on this topic, please submit a companion article.


DW DuBois

Steve,

Wish I could claim ownership but as mentioned, Tom beat me and I just copied his note from the archives.

Gene
Gene Gillam

Thank you for all of the detailed recommendations for ways to keep oil out of the distributor in my TDC.

After some reflection, I realized that it takes a few 2-3 hour Sunday drives for oil to build up to a sufficient amount to wipe clean. The oil builds up slowly over 20-30 hours of operation.

I'm a pilot. I live by checklists when I fly. I also use a pre-flight checklist before I take the TDC out for a Sunday drive. For now, I have decided to add an item, "Remove distributor cap, wipe down distributor cap, rotor, weights, and points" to my checklist right after, "Check oil level". Iwill leave oil on the surface below the weights so they may operate smoothly.

Wiping down the distributor will remove the scant amount of oil in the distributor, and it will let me keep an eye on any changes in the amount of oil that builds up over time. I bookmarked this page in cas something changes.

Erick

EB Blackwelder

Having my distributor rebuilt by Jeff Schlemmer of Advanced Distributors cured my oil problem. Before that my car would die every 200 to 300 miles. Swabbing out the distributor and running an index card between the points would get me going again.

Warmly,
Dave
Dave Braun

Thanks to Dave Braun for referring me to Advanced Distributors. I'll wipe out my distributor before every drive until that doesn't solve the problem, then I'll ship it to Advanced for a rebuild.

Erick
EB Blackwelder

This thread was discussed between 26/01/2016 and 03/02/2016

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