123 Distributor failures from oil?

[stphers]

What is the difference between a 123 dist and a normal dist? Shaft sizes diff? Spinning speed should be the same. Normal dist do not have this problem Is it the electronics in the system that is drawing the oil up? it is obvious that it is coming up the shaft and that is why the reverse threads were put in to throw the oil back, doesn't seem to work I have a hard time believing that there is too much pressure in the engine causing the oil to drive up the shaft, didn't do it with a normal dist what's different about the 123 dist?

Thanks, Rick

 

[Stevehose]

Capillarity?

I would think the reverse groove and a full blown oil seal would prevent that but what do I know.

 

[Ian C]

I run a staked Bosch distributor which drops a small but annoying amount of oil from the weep hole. Thought it was a faulty distributor so replaced it, same result. Have had many M10s and M30s over the years and never had this before.

 

[sfdon]

Ian- fuel injected or carb? Do you have vacuum present at your valve cover breather hose?

 

[Ian C]

Fuel injected, M90 Haltech, Schrick 284 maybe a minimal compression bump from head plane. I'm running a small catch can which feeds back to the throttle body. It was a bit too wet (oil) in the inlet manifold for my liking when I first fired it up. Its settled a bit now and less oil being caught, but still some. Ring gaps were within spec when assembled, but not by a lot.

 

[Stevehose]

Fuel injected, M90 Haltech, Schrick 284 maybe a minimal compression bump from head plane. I'm running a small catch can which feeds back to the throttle body. It was a bit too wet (oil) in the inlet manifold for my liking when I first fired it up. Its settled a bit now and less oil being caught, but still some. Ring gaps were within spec when assembled, but not by a lot.

What is the inner diameter of your catch can hoses? Which catch can system is it?

 

[Ian C]

Its a Mishimoto universal, quite compact, with a good separator. From the valve cover to the inlet its the size of the valve cover outlet, a tight fit over a barbed fitting, and a reducer needed in the return line to the throttle body. They do have various options for in and out fittings. Finding somewhere to mount it discreetly is the hard part for me, but it works well. I'd measure it for you but away from home for another week or so.

 

[Stevehose]

a reducer needed in the return line to the throttle body

I'd be curious as to what ID this is and if any other bottlenecks in the path when you have a chance, thanks.

 

[Stevehose]

What is the difference between a 123 dist and a normal dist? Shaft sizes diff? Spinning speed should be the same. Normal dist do not have this problem Is it the electronics in the system that is drawing the oil up? it is obvious that it is coming up the shaft and that is why the reverse threads were put in to throw the oil back, doesn't seem to work I have a hard time believing that there is too much pressure in the engine causing the oil to drive up the shaft, didn't do it with a normal dist what's different about the 123 dist?

Thanks, Rick

We're trying to determine this. The Bosch distributors have 4? drain holes so they must have designed for this, and Ian's post indicates that it can happen to a Bosch although not common. I'm thinking it's crankcase pressure from one or more situations which is why it's not consistent:

1. Improper valve cover breathing or restrictions (not using the vacuum-induced air cleaner assembly on a CS or smaller diameter hose/catch can system for us Weber sidedraft guys). Maybe a restriction in the valve cover baffle plate under the vent hole (I will investigate this on mine)?

2. Excessive blow-by that the cover vent-to-air cleaner (CS) or throttle body connection/intake suction (CSi) can't handle at higher rpm's. @adawil2002 comes to mind as someone with a CSi who's had this problem.

3. Faulty seal inside the 123, although I have both the reverse groove and a new seal and have the issue so I am doubtful about this.

4. If your engine leaks oil out of one or both crank seals, perhaps it's pressure causing this like it can in other cars.

There are numerous references on engine forums that if crankcase venting is not correct then oil seals etc can blow out. I think the 123 is basically the path of least resistance for this phenomenon.

I drove 125 miles over the weekend and will continue to monitor to see if increasing the diameter hose has helped. I'm also looking at devising a draft pipe to induce vacuum at the hose end at speed to help pull the blowby out better.

 

[Ohmess]

As to that last point, I would think the location of the hose end (and how far it extends) would impact the induced vacuum at speed. Where does your hose terminate?

 

[Stevehose]

As to that last point, I would think the location of the hose end (and how far it extends) would impact the induced vacuum at speed. Where does your hose terminate?

A little lower than where the oil pan bolts to the block behind the oil filter. I am designing a venturi device to attach the hose to and locate it in the slipstream, perhaps a little lower. If my leak returns I will give it a try.

 

[Ian C]

I removed the breather baffle cover in the rocker cover and cleaned the passages during the build so no restriction there, the catch can may have an effect, ( think I added it befor I noticed leak) but is essentially using the same diameters as each end of the factory elbow. It seems to flow ok as it pulls a heap of condensation from the system (local climate to blame, all our cars have it) and a small amount of oil. I had thought either excessive blow by or worn distributor shaft bushing the likely cause, it’s not passing the flat o ring on the body so must be climbing the shaft. The other possible contender is the drive gear from camshaft allowing excessive oil past but only a guess

 

[Stevehose]

The other possible contender is the drive gear from camshaft allowing excessive oil past but only a guess

I believe any excess oil from the drive gear spills over the "wall" of the upper cover down into the crankcase. The red line indicates where the oil level is in the timing case cover - covering about half of the distributor gear and very little if any of the dive gear. So any excess spills over that red line. Also, the point of entry is not the bottom of the gear but well above this level where the gear piece meets the distributor body.

 

[Stevehose]

Update: the Bosch has 3 drain holes:

The difference being that the 123 leak capillaries in between the 2 PCB’s and out the distributor cap more than dripping down the sides to the 1 drain hole it has.

 

[sfdon]

I would bring up the fact that in both FI and carbureted cars that BMW engineers made the hose coming off the valve cover both large and short for a reason.

 

[Stevehose]

I would bring up the fact that in both FI and carbureted cars that BMW engineers made the hose coming off the valve cover both large and short for a reason.

And to a vacuum source.

 

[Stevehose]

I thought about drilling a hole into the “wall” to lower the level of the oil so less is churned around and vaporized in this area but am not convinced this would make a difference.

 

[Stevehose]

Also, the point of entry of the 123 is farther away from the oil pool than the Bosch.

 

[sfdon]

After reading in the internet about leaking engine seals caused by positive crankcase pressures and seeing all of the aftermarket oil catch cans with 12volt vacuum pumps….hmmmmm. I‘m thinking maybe this is the time to try one. And- don’t we all remember replacing gunked up PCV valves. It’s a known issue.

 

[Ian C]

When I’m home I’ll remove the catch can and observe