Oiling Problem

Information relating to the Matchless G11 or AJS Model 30 600cc twin
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Oiling Problem

Postby paul knapp » Sat Jun 12, 2010 3:40 pm

After 20 miles the oil has thinned down enough to get past the seal, either because it has possibly been fitted back to front,(lip tensioner spring must face pinion) or it's lip is getting a little worn and isn't sealing on the sleeve.
Or if the pinion retaining bolt isn't tight, and the sleeve isn't firmly sandwiched between pinion and bearing, oil can weep between the seal sleeve and the armature shaft, coming out between the bearing housing and end cover and also finding it's way into the generator housing, as you have found.

Paul
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Oiling Problem

Postby GSAX1 » Sat Jun 12, 2010 7:29 pm

Are you sure it's the dynamo seal? It could be the oil filter cavity that is leaking. The pressure is quite high there, and it will force oil out under the dynamo.

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Oiling Problem

Postby trophy » Sun Jun 13, 2010 1:58 pm

quote:

Are you sure it's the dynamo seal? It could be the oil filter cavity that is leaking. The pressure is quite high there, and it will force oil out under the dynamo.

Michael


This is exactly what happened to me when I restored my G9 recently. I stupidly forgot to fit the round paper gasket to the oil filter cavity when putting the two halves of the crankcases together. Trouble is that the remedy is a lot of work. I do recall reading that someone had cured this by machining the crankcases to accept an O seal instead of the paper gasket.
Ride safe all.

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Oiling Problem

Postby Groily » Sun Jun 13, 2010 5:26 pm

Well, it's one of the three -
timing side to dynamo gasket,
dynamo oil seal, or
crankcase.
Been there and got every T shirt more than once. However, I'd expect a crankcase leak to show up from cold or soon after as the pressure is very high then, it'll ooze out and then trickle faster when the oil's hot..
I'd favour the dynamo oil seal and the little sleeve on the armature in this particular case - doesn't take much for the seal to lose its edge. One symptom I've found, if the seal is failing, is that the dynamo doesn't kick in as soon as usual - because the commutator is mucky and the brushes have to carve their way through the slime to get going.

On the cases, some people say - including in a parallel thread hereabouts, - 'don't use the little 0 gasket, just use a smear of something suitable all round the joint'; Biscuit said make a gasket to go between the cases all round. Laborious and long job with massive scope for error and cursing, but worked for me when I was really struggling a while back. I can't think of anything he ever said that wasn't right.
The O ring trick would be good too I imagine.

However, bikes seem to vary: one of mine habitually leaked due to one or other or a combination of these things, t'other I have is dry as a bone and always has been, even when thrown together relatively carelessly. State of the mating parts has to be a lot to do with it.

One time I cured things by replacing the dynamo oil-seal retaining plate, which was well past its best in terms of fit into the recess on the rear of the t'side case.

Really irritating leak though, this one, and sometimes hard to cure, partly because there are quite a few possible reasons for it.

Be interested to know what the actual prob was when you know yourself!

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Oiling Problem

Postby laxy » Sun Jun 13, 2010 8:38 pm

I had a persistant leak from the dynamo to crankcase joint on my 650.
I fitted an O ring with a light film of hylomar instead of the cork washer.
I also didnt over tighten the strap or the small bolt in the timing side crankcase that pulls the dynamo up snugly.
Never leaked again after that

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Oiling Problem

Postby freddie 136 » Mon Jun 14, 2010 9:43 am


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Oiling Problem

Postby freddie 136 » Mon Jun 14, 2010 9:48 am

Hi,thanks for all the replies,looks like i have a bit of a job on trying to find the problem but will start later this week on the bike, am i right in thinking that the oil seal in the dynamo has to have the end plate and bearing took off to replace,cant remember off hand myself till i take it apart again,and if so do i need a puller to get it off,thanks again Fred.

Edited by - freddie 136 on 14 Jun 2010 09:50:15 AM

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Oiling Problem

Postby freddie 136 » Sat Jun 19, 2010 7:30 pm

Hello again,just an update for interested party's re oil problem. Took the dynamo off yesterday and striped it down,bit of oil on the carbon brush area but not much,with the armature and end plate attached i re fitted it and went about 30 miles this was to see if i could tell if the oil leak was from the oil seal / cork gasket area or between the engine casing joint, funny thing is there was not much leak from any area only a smear from the cases and the same from the gasket. After cleaning the dynamo and fitting a new oil seal i refitted the dynamo and have just done 60 miles the only oil visible now is about a spot of oil on the end plate that must have come from the cork gasket area, also when tightening the dynamo strap i did not try to get it as tight as before just enough to hold the bolt [as one member suggested] so with a bit of luck the problem might be solved if so then all i have done is to renew the oil seal [don't really think this was the problem] re tapped the holding bolt with a 5mm stainless bolt,[holds really good now] and left the dynamo strap a little looser. thank you to all who helped much appreciated, cheers Fred.

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