Oil leaks

["Slack Alice" Simon]

Looks like mine on a good day.


One thing you MUST do - run round all the block holding down nuts with a spanner - they can come loose.

Front and rear are a pig to get at, but if there is any sign of the three each side being tightenable (!), then attention is desirable.

Short spanner - they mustn't be over tightened, or you will pull the stud out of the crankcase and the engine will have to come out.

[Steve kay]

Like Peter Arnold, I followed forum advise and on the Ruby, made the sump and bottom of crankcase surfaces spotlessly clean before using
a silicon gasket. Also made sure to tighten bolts as evenly as possible but taking care not to tighten too much, this is just a location joint and certainly not a mechanical one. That combined with an alloy sump makes an oil tight joint. But, cries anyone who has parked next to it in a pub car park, whence comes all that oil? The valve guides cannot be perfect, there was leakage from the valve chest cover until I put on a cover with a breather pipe, there is now gentle but continuing emission from the breather pipe. Morgan owning pals with old JAPs tell me that Austin Seven engines are as tight as a South Morningside auntie's purse, so not to worry about a pint or two.

Old Dave, tickover might not tell you a great deal, serious revs can be quite different.

[Chris KC]

Looks like mine on a good day.


One thing you MUST do - run round all the block holding down nuts with a spanner - they can come loose.

Front and rear are a pig to get at, but if there is any sign of the three each side being tightenable (!), then attention is desirable.

Short spanner - they mustn't be over tightened, or you will pull the stud out of the crankcase and the engine will have to come out.

I heartily endorse Simon's advice.
Here's what happens when you over-tighten:

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[Reckless Rat]

I second Chris' comments above regarding the block holding down studs. It is a far better option to accept a bit of oil seepage from the block/crankcase joint than to overtighten one of the holding down nuts and risk breaking one. If the joint is seeping no amount of tightening will stop it. The only remedy is an engine strip, a proper clean and a silicone gasket. I snapped the middle one in the valve chest attempting this so I know from my own experience that it was a BIG mistake!



The leak on the o/s of your engine does appear to be coming from the oil jet cover nut. That's a reasonably easy fix, just remove it, clean it up and replace with a fibre washer. Again, don't overtighten, and don't drop any rubbish down the hole. You can poke the oil jet with a straightened out paper clip before replacing the cover nut.

[Old Dave]

Well thank you everyone for all the great advice.

Yes Chris and Bruce were correct that oil was exiting passed the front jet cover nut. It didn’t appear to be very loose and would not “nip” down. I suspect that the thread is fragile but not totally stripped. I have replaced the fibre washer but …….. Obviously I have been careful the couple of times I have checked the jet in the last 5 years. Only applied a nip. The boot is in and tightened but I am not sure it won’t slacken again. Only thoughts on a more secure fitting?

[David Stepney]

A sliver of PTFE tape wrapped around the plug thread, perhaps? Or perhaps a new plug. The brass can wear as well as the aluminium.

[Chris KC]

Well that's good news, I think!

Jamie at Seven Workshop sells oversize screws specifically for this situation.
I'm not sure I'd attempt to thread it oversize in situ though, unless you are really confident you can catch all the swarf generated. 
Again, perhaps a job for next time the engine's apart?

If there's still a viable thread I think I'd try a locking sealant on it e.g. perhaps Loctite 243? (medium strength, tolerates some contamination, suitable for all metals, seals threads, and most importantly, dismountable!) Clean the threads as best you can first.

A new (same size) plug <might> give you better thread engagement if the old one is worn.

["Slack Alice" Simon]

I have had some success making replacements for the fibre washers from silicon sheet.

With a thin steel washer, and a careful judgement of tightness, an acceptable seal can be made.

After all, these screws are not holding anything on, just filling a hole.

I have used such sealing washers on bodged fuel tank and oil sump drain plugs.

They work well, I don't consider them a permanent solution, though.

I bought a set of hole punches second hand, they are really handy for making gaskets from silicon sheets.

[Old Dave]

Thanks for all the advice everyone. Much appreciated. Hopefully I will get it suitably dripping instead of pouring.

[David Stepney]

Hi Referring back to a remark earlier in.this thread concerning the tightness of the block to crankcase nuts, perhaps I should say that a cause of loose block to crankcase bolts is an over advanced engine. In this respect, I shall share a cautionary tale: some 40 years ago I had a fairly well tuned special, which had an engine that produced about 25 bhp and gave me a car that would genuinely reach 70 mph. The engine ran a bit on the growly side,and was probably over advanced, but it went well. On day, at over a mile a minute, the block came off the crankcase, having pulled all the studs up by their roots. The crankcase was a write off.