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MG Midget and Sprite Technical - distributor o ring?

Have oil coming from dizzy shaft. Should there be an o-ring on a 1098cg? Numbers on dizzy are 40919 A 263, 25D I guess, Lucas. Moss catelog shows an o ring by the thrust washer at the dog. Haynes and Bently do not. Different distributors I guess. Ideas?


J Van Dyke

Yes, different distributors. It was a modification along the line somewhere. Distributors originally fitted with the o-ring had a groove on the shank which yours hasn't got. It would be an easy matter to turn a groove if you wanted to fit one, provided you match the groove to the o-ring.
Paul Walbran

If you lathe one onto the shaft, make it above the drilling that allows lubrication to the inner shaft of the dizzy. Should be a hole halfway up the outer shaft with a recessed line up to it from the dog end. Alternatively, drill the casting in the area above the clamp that almost looks 'designed' for a grease/oil nipple so that you can inject lubricant.

My opinion, for what it is worth! :o)
rob multi-sheds thomas

J. The later model distributors did away with the rubber O ring because it was not needed. There should be no oil getting into that area.

The distributor drive engages the camshaft and the skew gear area is lubricated off the camshaft with a very small amount of oil going up the shaft. The upper end of the dizzy drive is held in place by the distributor housing which fits into the block and keeps the distributor drive from being forced upwards. It, also, keeps oil from moving into the area where the distributor body fits into the engine. Hence, both the rubber O ring and the hole through the distributor body and bushing were deleted in later models--there is no oil there to lubricate them and no need for these features.

There is, however, a brass oil plug near the distributor and hidden by it. This plug has been known to develop a leak, causing oil to be near the distributor. This is a plug into the pressurized portion of the oil system and, if not firmly fitted, will leak. The distributor drive gear is only lubricated by non-pressurized oil splashed on from the skew gear of the camshaft--going at an upwards angle.

The second source of oil near the dizzy is leaking from the rocker arm cover.

Pull the dizzy out of the dizzy housing and take a look inside the housing. I have always found it dry in there when I do a tune up. For oil to be coming from this source, the entire housing, where the distributor body fits in, would have to be oil filled. Never seen this myself and cannot think of any way it could happen.

Les
Les Bengtson

Thanks again for the info. I tightened that plug, it was tight but I got a bit more out of it. Wonder if there is a copper washer under it or something I can replace. There was oil on the bottom of the dizzy, top of the starter and making it to the ground. Maybe that did it, if not, we'll try something else.
BTW
great community here, hope I can give some back someday if I ever get to that point!
J Van Dyke

Your distributor is the correct model for your 10CG engine: a Lucas 25D4 with model # 40919A.
The # 263 indicates it was made in february 1963 so it probably was already on your car when it left the Abingdon factory.
There is NO O-ring on it. Exactly as Les indicates: it shouldn't leak there as it is lubricated by splash oil only.
He's probably right on the brass "banjo" connection too. This is high pressure feed oil straight from the oil pump outlet. There should be copper washers under and on top of the banjo...
Hope this helps,

Nick, '63midget.
D.G.J. Herwegh

I asked this same question another place, they seem to think it is supposed to have an o ring up near the top end. Not sure what this "banjo" fitting is. I was thinking of the 7/16" bolt head I see under the pinch clamp, in the housing "ear".
Here's a pic of a groove that might need an o ring?


J Van Dyke

J. Yes, some of the early distributors came with a rubber O ring. This was discontinued because it was not needed and made it slightly more difficult to install the distributor body into the distributor housing on the engine block. Later distributors did not have the O ring, but may have had the groove for it until the production blue prints were changed.

I do not have an A series block to hand to examine. On the B series engine I just looked at (should be similar), there are two brass plugs near the engine boss that accepts the distributor housing. Both have been known to leak over the years, causing pressurized oil to be leaked from the area just below the distributor.

A "Banjo" bolt, or banjo fitting, is what is used with the SU electric fuel pump and a few other places. It is a circular brass fitting, about 1/2" thick, having a neck for a fuel line or fluid hose to attach to it. It uses a special hollow shafted bolt with a hole drilled through it from side to side. I do not see any banjo type fitting closer than the oil filter assembly. But, again, all I have is a B series block to look at.

Les
Les Bengtson

I understand what a banjo fitting is, but don't have any such anywhere near the distributor. So, to sum up, I'm not sure if the leak is through the shaft or that bolt that sits in the flange of the dist. mount. There was oil puddled in the recess for that bolt but there would be if it was coming from the shaft too.
I think I'll pull it again and try an o ring even though it seems I shouldn't need one.
My other leak is from the side cover vent pipe, which probably shouldn't be dumping oil either. Maybe too much blow by from worn rings? Not sure if that even make sense.
I'll also have to plan a compression and leak down test, which I've done precious little of on any engine and never yet on an A series.
Still haven't messed with valve lash either.....
J Van Dyke

No banjo bolt ??? There is no external oil pipe running from the rear of the block towards the oil filter housing on your car ? (Modified oil filter perhaps ?)
Of course the connection to the oil pressure gauge is also near the distributor; these can also seep some oil.
If the distributor housing really is the culprit then this would indicate an excessive crankcase pressure.
(Might be the cause of the vent-pipe leak too)
No leaks around the flywheel bell-housing or crankshaft pulley ?

Nick, '63Midget.
Nick

Oil cooler line from the point where that banjo would be most likely. Excessive crankcase pressure seems plausible. What could cause that?
J Van Dyke

Did a quick compression test. Warm engine, all on it's own battery though.
Dry Wet
#1 180 235
#2 180 210
#3 160 175
#4 180 210

Pulled dizzy and added o ring for kicks.
I don't think that's the source though, the shaft seemed pretty dry to me as did the cavity. There is a rather disturbing trail coming down the rear of the block from the head gasket. It was there when I pulled the motor, I cleaned the block and repainted and it slowly came back, it thought the paint just hadn't stuck well but maybe the head gasket is bad. It's always dry to the touch though, I'd think if it were the source of oil it'd be oily.

J Van Dyke

This thread was discussed between 06/08/2008 and 08/08/2008

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