Oil leak at c/case union

crawsue · Post by **crawsue** » Sun Feb 17, 2008 5:20 pm

The G80 has been up on the centre stand for about 4 weeks while I replace the rear rim,to my horror it is losing oil out of the "feed" pipe union to the crankcase,not a large ammount,but having spent a lot of time making the top end and primary c/case oil tight it is more than a little annoying.Any ideas on how you get a spanner in to tighten it up? It is so tight to the bottom frame rails that a normal open -ender just wont get in.Thanks in anticipation for any answer that doesn't include advice about removing engine from frame!!!

TommoT · Post by **TommoT** » Sun Feb 17, 2008 5:33 pm

Duncan, I have not found any other method than removing the footrest, exhaust and return pipe union. This gives room enough for a slim open ended spanner. It also gives you an opportunity to anneal the copper pipe stubs, where they tighten up against the taperede sealing surface in the union. This should secure an oiltight pipe. I don't see any harm in using a little Locktight here, to avoid these unions and pipes working themselves loose.

Have fun

(mind you Locktight on the threads, not the sealing surfaces!)Edited by - TommoT on 17 Feb 2008 5:37:28 PM

itma · Post by **itma** » Sun Feb 17, 2008 5:37 pm

Get yourself an old flat ring spanner and grind enough out of the ring to let it slip over the pipe.
Do not over do it, as if this thread is at all wonky it will strip, and/or crack the boss it fits into....deeeeeeeeeeeeeeeeep sh!te time

Another way is to drain the tank detach the relevant pipe and fiddle the spanner along the pipe.
A flat ring spanner is best; you can buy these types of spanners as union nut spanners but mostly only metric or UNF sizes.
Do be VERY careful here and an open end spanner should never be used on these nuts.

crawsue · Post by **crawsue** » Sun Feb 17, 2008 6:27 pm

Thanks,both for your advice, further questions arise,before I start grinding away at my collection of ring spanners,any idea what size this coupling is? The connection for the feed pipe seems to be in two sections ,as opposed to the return which looks like a one-peice "compression" type fixing.There are no pictures of the connections in place that I can find and I am unsure which part is leaking....should I attempt to tighten the "nut" closest to the casing or the outer one which presumably holds the copper tube to the outer connecting piece.....in other words which joint is more likely to fail? Having re-read this 14 times it doesn't make much sense!I suppose what I'm trying to ascertain is.....is this coupling prone to "working loose" Ken,I take on board your concerns about possible major sh!t with overtightening,there is so little space between the coupling and the bolt which secures the engine plate,it is going to be like brain surgery!

TommoT · Post by **TommoT** » Sun Feb 17, 2008 10:07 pm

Yes, I was perhaps slightly over enthusiastic suggesting to just spanner away with the open ended same, but it can be done and saves you grinding away on a perfectly good spanner. But Ken's solutions is far more fool proof and one that I will follow myself once a spanner becomes available for that purpose. I have not had these couplings come loose so cannot make an educated guess which one is more likely to become so, but they all need to be tight to keep oil inside The problem with the open ended spanner is that when the jaws hit either the crankcase or something else solid, you're led to believe that the joint is locking up when instead you apply side force to the union, effectively breaking the aluminium thread out and away from crankcase = disaster

crawsue · Post by **crawsue** » Mon Feb 18, 2008 1:57 pm

Tom,while I look for a suitable tool to modify,I am just going to monitor the drip,like you I am more than a bit worried about doing more harm than good....it is an old British 'bike,people expect it to leak a bit!It is just so annoying after getting all the usual suspects oil tight,but hey-ho,I could be living in India! (see Circlip)

Circlip · Post by **Circlip** » Mon Feb 18, 2008 3:21 pm

I am not familiar with the particular bike or of the pipe ,--but at times like this instead of heaving on the thing trying to stop the leak I torque then loose then torque again,-- a few times.

If it feels spongy and not torquing,-- stop.

I have made plastic washers from squeezy bottles, punch out the center and then cut out the outside.

Copper is Ok on new stuff, plastic is much more able to conform to uneven surfaces.

crawsue · Post by **crawsue** » Mon Feb 18, 2008 5:38 pm

The main problem ,Graham,is that the in & out unions are very close and almost completely hemmed in by the bottom frame rail and rear engine plates.I was hoping that some lateral thinking guy would say something like...."easy peasy,just loosen engine mounts,jack -up with a car jack and tighten...."but I was just whistlin' in the wind,I'm afraid.

itma · Post by **itma** » Mon Feb 18, 2008 6:16 pm

Search the boot sales, you`ll need a 5/16 whit and a 3/8 whit ring, pref 2
Cut the gap with a thin cutting disc on an angle grinder; eye protection especially if chromed, as it will flake off everywhere.
Start with the adaptor and work back along the pipe.
Hold the adaptor while you tighten the union.
this is where the 2nd spanner comes in.
Do not over tighten as you will have seriously lowered the strength of the spanner, and these do not need to be that tight.
I think it is a good idea to slacken all the unions, just to be on the safe side, and again work back to the tank.
If you do an ebay search for union nut/flare nut spanners, you will see the idea.
these however are only metric or UNF sizes, so we don't do that do we?
Also a ring spanner will give you smaller bites in this restricted area; I'd take off pipe and footrest as well.
Now get out in the bloody shed!!

crawsue · Post by **crawsue** » Mon Feb 18, 2008 8:08 pm

Cheers,Ken...I think I'll watch it drip...lifes to short....oh no ,I'll never be able to get to sleep,thinking about it...where's the garage keys.