Oil Leaks - Singles

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Keith.owen
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Oil Leaks - Singles

Postby Keith.owen » Wed Jul 29, 2020 8:42 am

Hi,
I currently have the head off of my bike and want to use this as a chance to solve a few minor oil leaks.

My question is 'where are the weak spots' on the iron head Ariel singles (NH & VH)?

I fitted a Yamaha reed valve to the crankcase breather in lieu of the ball valve and on the timing case I fitted a Royal Enfield non return valve, its a pipe with one end flattened.

I have not suffered from oil leakage from the rocker gaskets (as far as I can see) but oil is still coming out from somewhere (perhaps the exhaust lifter) not a lot but still gets all over the place.

Also oil is coming out of the magdyno; it's not getting into the mag, but comes out at the joint with the dynamo and also collects underneath it as well as from the outer gear cover. Again, no oil from between magneto and timing case.

I fitted that paper washer over the mag spindle before fitting the sprocket, but it doesn't seem to do much...........

When I've had the outer cover off there is oil in it but not much. Of note I did do the cam chest oil level mod.

Any suggestions anyone? Its driving me mad!!!

Keith :?
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Re: Oil Leaks - Singles

Postby volker.halbach » Wed Jul 29, 2020 11:55 am

Maybe there is still too much oil in the timing case and you were so successful in fixing the leaks lower down that it's squeezed out in unusual places? If the oil flow from the outer timing case into the inner is restricted, it may have enough time to flow back into the crankcase while you remove the cover, and you find only a normal amount of oil. The location of the holes through which oil flows back was changed at some point. The gaskets from Drags between crankcase and inner timing case completely cover the two drillings on my engine and I have to cut them back. After removing the outer cover, you can poke a small screwdriver through the holes to see whether there is any obstacle. Just an idea.

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Re: Oil Leaks - Singles

Postby DaveCrombie » Wed Jul 29, 2020 12:20 pm

Hi Keith,

Funnily enough I have had exactly the same problem on my bog-standard 56 VH500, and just this weekend had to be rescued by recovery van from Anglesey with no spark from the mag at all :( . Not the end to my holiday I wanted! Oil had been dripping out of end of the dynamo for some while too. So I took the mag off on Sunday, and right enough, all the earth ring and brush were covered in oil inside, so it was not earthing back. Cleaned all this up, and hey presto, a spark.

But the issue remains, why is this oil being pushed up into the magdyno front casing in the first place?? I also have a thin home-made seal either side of the mag shaft, (made of gasket paper), which helps a bit, but there's nothing to stop oil going into the dynamo. I also assume that the timing chain flings it all up that end of the casing anyway, so it's a case of the oil being in the wrong place at the wrong time.

Best suggestion I've had so far, (thanks Jim Haydock), is that the breathers really aren't good enough, and I might be better off removing the non return valve on the timing case one. The crankcase breather on the other side is just an open pipe, but it seems even these two might not be able to relieve pressure in the cases. I read the other posts about rocker cover breathers, but frankly got a bit confused about the various ideas about pressure differentials - I've never had this issue on any number of other old knackered British bike engines, with or without worn bores/rings etc., it seems to be an Ariel thing. Lucky us!

Volker, thanks for your comment about the oil holes and gaskets, I did remember checking these, and I don't think any were blocked off by the new gasket I used, but as I have the case off I can double check.

Has anyone successfully modified the existing breathers to solve this issue perhaps? (I am no engineer, so won't be able to make up new brass pipes, add threads etc...or anything like that).

Thanks, David

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Re: Oil Leaks - Singles

Postby jj.palmer » Wed Jul 29, 2020 1:52 pm

See pics. of home made oil seal for between the timing chain case and the magneto, the breathers are has original, it has worked well for a number of years.
The seal caters for any offset between the hole in the timing chain case and the spindle of the magneto, see alignment marks in the pics..

Hope this helps.

John P.
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Re: Oil Leaks - Singles

Postby Keith.owen » Wed Jul 29, 2020 2:01 pm

Hi John,
This looks as though it is likely more effective than a simple paper washer.

The challenge is, as I see it, that the spindle position varies in relation to the hole in the case, according to the position of the magneto adopted to acquire the correct chain tension.

Keith
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Re: Oil Leaks - Singles

Postby DaveCrombie » Wed Jul 29, 2020 3:57 pm

Hi John, yes looks like a very neat solution, but I have no way of making such a thing unfortunately. Is there a cut slot in the round rubber seal to hold the washer in place, or does it just sit behind the black seal?
As the breathers are standard, presumably you don't have any undue crankcase pressure issues on your engine? (Or if you did, perhaps it isn't an issue as the oil can't get to the magdyno!)
Thanks v much for the pictures.
David

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Re: Oil Leaks - Singles

Postby jj.palmer » Wed Jul 29, 2020 4:01 pm

Hi,I will draw a sketch which may explain it in more detail, see tomorrows morning post.

John P.

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Re: Oil Leaks - Singles

Postby Keith.owen » Wed Jul 29, 2020 4:36 pm

Hi JJ,
I also look forward to your post.

Thanks,
Keith
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Re: Oil Leaks - Singles

Postby robjameson » Wed Jul 29, 2020 11:32 pm

I have a Yamaha reed valve, which I have connected to both breathers via a t piece. I have virtually no leakage from that part of the engine any more.

I still have a leak at the rocker feed, but that is a different issue altogether.
Rob Jameson
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Re: Oil Leaks - Singles

Postby alan.moore » Thu Jul 30, 2020 12:04 am

Keith,
Have you tried blowing down one of those Enfield 'Duck bill' breather tubes? I bought a couple from Hitchcocks for my VH and there was no way I could get them to pass any air by blowing through them, the plastic/rubber of the 'Duck bill' was just too stiff. They were certainly much more restrictive than the old ball valves. Like you I've used the Yamaha reed valve (mine only has the breathers on the timing case both T'd to one reed valve). Compared with the very small area for airflow in the ball valve breathers these reed valves can flow a significant amount of air.

I've also found some of the timing case gaskets cover that oil return hole either fully or partially so best to check.

That big rubber washer at the back of the timing case really only stops oil mist getting out the big hole in the case and running down the back of the case. It seals between the back of the timing case and the front of the mag/dynamo triangular cover. The original seal has a big hole and a metal ring round it to support the seal. The big hole is needed so you can adjust the timing chain tension by moving the mag rearwards. The downside of having a good seal here is that any crankcase pressure/oil is forced up the sides of the mag spindle into the triangular cover and, if that is well sealed, it has to go somewhere. As the Mag and dynamo spindles have no seals it goes into the Mag and dynamo hence the oil contamination. The paper washer over the mag spindle does not really do anything significant.

My view is that, if the timing case is draining oil correctly back into the engine and you have no excessive build up of oil in the timing case, then excessive crankcase pressure is likely to be the root cause of these oiling issues. That could be due to an engine where the piston is not fully run in, or a worn piston/rings/bore.

With my newly rebuilt (rebore/piston) VH (1939 with two ball valve breathers) with the dynamo removed if i turned the engine over on the kickstart I could clearly hear the air coming out of the triangular cover. If I removed a valve cap this movement of air stopped. This just goes to show that the easiest route for any crankcase pressure to escape is via the timing case, mag and dynamo.

Finally, there are those with VH's (Mr Paul Jameson is one I believe) who run the original ball valve breather setups and have had no issues. So clearly the system is capable of working without filling the Mag with oil. In fact on the WNG Ariel deleted the lower breather leaving just the one behind the timing cover.

Food for thought.
Cheers
Alan
1939 VH Redhunter;1942 RN WNG;1951 Triumph 6T Thunderbird;1970 BSA B175 Bantam;1986 Yamaha SRX600 single
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