MG TD TF 1500 Oil in Distributor BBS discussion at MG-Cars.net

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

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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

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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

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Photo of venting

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Another view

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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.

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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

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with o-ring

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With Seal

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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

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

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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

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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.

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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

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

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