Wet sumping, new cause?

My original 750 Fastback crankcase had a crack and I replaced it with a used 850 Mk 1.
After assambly the engine I noticed it wet sump badly. The reason surprised me. The oil come out a very small hole in the crankcase in the timing side. Have others seen similar? It's probably time to find my TIG and have some weld on.

Looking at your photos I think I can see a little casting imperfection just below the plugged hole. Before I went to welding that I would also want to check the plug there real good to make sure it is not causing the problem. That plug looks like it is too far in - so it may be loose in the threads and not sealing perfectly. If you do find that the cause is that little imperfection in the casting then I would be tempted to use JB Weld rather than actually welding on it. It is on the suction side of the oil pump so it only has to hold the pressure of gravity fed hot oil. I would drill into it with a small bit (5/64ths or 1/8th) and then clean it with brake clean and use the high strength-24 hour cure-JB Weld. Or, alternatively, you could drill a bit deeper and tap the hole for a 6-32 screw and install that with some JB Weld or lock-tite.

Kvinnhering said:

My original 750 Fastback crankcase had a crack and I replaced it with a used 850 Mk 1.
After assambly the engine I noticed it wet sump badly. The reason surprised me. The oil come out a very small hole in the crankcase in the timing side. Have others seen similar? It's probably time to find my TIG and have some weld on.

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View attachment 6598

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There should be no source of oil from the brass plug.
There is a source of oil from the slotted head plug below it.
Before I would want to weld that close to a bearing bore I would attempt to repair it by using a long threaded rod to replace the slotted plug. It is probably a porous area in the passage behind the plug so a longer threaded rod with epoxy would stand a good chance or repairing it.
That passage intersects the feed passage to the pump so make sure the threaded rod or epoxy does not block the pump feed passage.

Instead of welding the hole in the porous engine case, which may cause warping it might be possible to repair the case by reaming the oil inlet port then pressing in a special sleeve that is capped off one end back into the port using loctite sealer. Once installed, go ahead and cross drill the sleeve at the oil pump port. You wouldn't need to cross drill the threaded port if you are using an 850 Mark 3 timing cover or a modified earlier type timing cover.

I made a quick drawing to give you an idea what I am talking about. Of course you would have to dismantle the engine to do this type of work.



I hope this is of some help,

Peter Joe

comnoz said:

There should be no source of oil from the brass plug.
There is a source of oil from the slotted head plug below it.
Before I would want to weld that close to a bearing bore I would attempt to repair it by using a long threaded rod to replace the slotted plug. It is probably a porous area in the passage behind the plug so a longer threaded rod with epoxy would stand a good chance or repairing it.
That passage intersects the feed passage to the pump so make sure the threaded rod or epoxy does not block the pump feed passage.

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The oil comes frome the feed chanel from tank, not the threaded passage. Tonight I managed to squeezed JB Weld into the pore after a thorough cleaning. Hope the problem are resolved.

PeterJoe said:

Instead of welding the hole in the porous engine case, which may cause warping it might be possible to repair the case by reaming the oil inlet port then pressing in a special sleeve that is capped off one end back into the port using loctite sealer. Once installed, go ahead and cross drill the sleeve at the oil pump port. You wouldn't need to cross drill the threaded port if you are using an 850 Mark 3 timing cover or a modified earlier type timing cover.

I made a quick drawing to give you an idea what I am talking about. Of course you would have to dismantle the engine to do this type of work.

I hope this is of some help,

Peter Joe

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Thank you for a good solution Peter Joe.
First, I will try with JB Weld and hope it solves the problem. If not, I will try your solution. Thanks again.

Tonight I connected the oil hoses again and filled the oil tank.
Not a single drop came through the pore after three hours. Problem solved (I hope).
Tank you for helping me.