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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Topic: OIL LEAK
    Posted: 03 Sep 2019 at 09:37
My V7Special has an oil leak which appears to be coming from the right hand cylinder base joint.I have made two unsuccessful attempts to seal it and I'm about to make another.I've replaced the barrels on three big blocks over the years without problems apart from this one joint.
I had thought that the oil might be working its way up the outer cylinder head stud from where it screws into the crankcase,where there is a small o ring placed.Having removed said stud and its opposite (12 'o'clock)number. I found that the holes into which the studs screw are blind holes so no oil can seep up the threads;why the 'o'ring then? Apparently some of the early twins were not even fitted with the 'o' rings.
This will be my third attempt at solving this problem,if this attempt fails then I shall be more inclined to suspect crank case porosity.
So,main question.Why are 'o'rings fitted in this particular application.Was it in case the drilling for the studs was too deep and broke through into the crank case void?
Please enlighten me.

Blind hole.

Edited by Dave P. - 03 Sep 2019 at 10:04
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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jpc View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpc Quote  Post ReplyReply Direct Link To This Post Posted: 03 Sep 2019 at 12:19
I'm as clueless as you are about the 6 & 12 o'clock o-rings, but have you tried re-torquing the heads
long after it seems that everything should have stopped settling ?  I'm talking about tens of thousands of miles, and finding some slack even then.
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 03 Sep 2019 at 13:01
Hi JPC. Yes I've re torqued the heads but to no avail.
As said above,I've done this job a number of times, on an 850T an 850GT and on the V7 Special.The r/h pot on the V7 Special is the only one which has leaked.I can't see where the oil is coming from around the base joint.What I see is a wet crankcase wall beneath that joint and oil lying on the uppermost horizontal web/fin of the lower crankcase.
This is why I wonder about the possibility of crankcase porosity.I just know I'll put it all back together (for the third time)and the bugger will leak again!
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Amboman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Amboman Quote  Post ReplyReply Direct Link To This Post Posted: 03 Sep 2019 at 14:07
Did you use any sealer? On "serial leakers" I apply sealer to the base gasket surfaces. My sealer of choice is Permatex Aviation or the almost identical Permatex 300.
Charlie
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 03 Sep 2019 at 15:52
Thanks Charlie. I shall try using a sealant.Permatex appears to be difficult to find in the UK so I'll use either Wellseal or Hylomar Blue both of which are advertised as being "Rolls Royce approved" and both of which I have found to be very effective.
What about the "o"rings on the short 6 and 12 o clock studs? Any idea why?
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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GUZZIPETE View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GUZZIPETE Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 2019 at 19:46
Hi Dave

Coincidentally, I'm currently doing the exact same job on my 850T. I have had a persistent oil leak in that area for a couple of years. It gradually pools behind one of the crankcase casting webs above the RH cylinder, until it overflows to the next one and then gradually down the side of the engine if left for long enough.

Initially I thought it was coming from the distributor-body flange, and changed the gasket, but no change.

When I took the barrel off the O rings looked very degraded. I see even Mr Richardson doesn't offer an explanation of what the 2 bottom O rings do, but he does mention including them. I don't fancy using Hylomar myself, as it will make any future disassembly more difficult.

Your suggestion of casting porosity is interesting, but I think the oil build up is probably too rapid for that in my case.

I'm basically working on a process of elimination. I let you know how it goes.

Pete
1971 Moto Guzzi V7 Special
1976 Moto Guzzi 850T
1977 Moto Guzzi Convert
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Mike H View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 2019 at 20:19
Originally posted by GUZZIPETE GUZZIPETE wrote:

When I took the barrel off the O rings looked very degraded.


They always do. They are virtually crushed on assembly and torquing down the head. Cannot be reused so I always had a supply amongst my spares in case needed in a hurry and it's a weekend.

Quote
I see even Mr Richardson doesn't offer an explanation of what the 2 bottom O rings do, but he does mention including them.


Only reason I can think of, if there's a leak across the gasket between crankcase and the hole, the oil can't go up alongside the stud and appear at the top nut.

Just FYI, my 850 Tonti had a constant RH cyl base leak too, never gushing out but always a "damp patch" there, I think I had the barrel off and back on at least twice, always with new base gasket, but was never a permanently fix it always came back.








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GUZZIPETE View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GUZZIPETE Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 2019 at 21:14
That's interesting about the persistance of the leak on your T Dave. I've had the bike for 6 years and it's only the last couple of years I've had the leak. So I hope I can eradicate it, but I'll see how it goes. 
1971 Moto Guzzi V7 Special
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1977 Moto Guzzi Convert
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 2019 at 21:21
This is all very encouraging Pete and Mike Maybe the R/H cylinder base leak is some kind of Guzzi tradition,any more out there ??

Seriously though,I will use Hylomar on the joint Pete because if it works there should not be any other occasion to dismantle those parts.Unless there's a major blow up of course. The O rings ?? My guess is that they may have been added as a precaution in case Luigi got over enthusiastic when drilling those stud holes and broke through into the oily void.
Who knows??
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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GUZZIPETE View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GUZZIPETE Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 2019 at 21:50
Sorry Mike, I thought your post was from Dave. But it seems it applies to him too anyway.

I'm surprised I haven't seen more about this issue over the years. It seems like a common problem. 
1971 Moto Guzzi V7 Special
1976 Moto Guzzi 850T
1977 Moto Guzzi Convert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote saultrader Quote  Post ReplyReply Direct Link To This Post Posted: 05 Sep 2019 at 11:02
All my bikes leak oil in various places and amounts. Whilst I glibly describe it as an anti-corrosion system, I put it down to working on engines using one inch drive sockets with 3ft long bars. I'm always wary of ripping 10mm studs out of questionable castings. Irrational or what?
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GUZZIPETE View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GUZZIPETE Quote  Post ReplyReply Direct Link To This Post Posted: 05 Sep 2019 at 18:04
Oil leaks go with the territory if we persist using these 40+ year old contraptions.
Messing about with Land Rovers for the last 35 years or so soon taught me that oil retention is never more than an aspiration.
1971 Moto Guzzi V7 Special
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1977 Moto Guzzi Convert
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 05 Sep 2019 at 19:51
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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Tony-C View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tony-C Quote  Post ReplyReply Direct Link To This Post Posted: 05 Sep 2019 at 19:59
Regards oil leaks, 40 year old contraptions, and Land Rovers. . . A good friend of mine, ( a Land Rover aficionado ), says that his oil leaks tell him that "There is oil in there". . . "When the leak stops, it's time to put some in.!" Regards, Tony
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Dave P. View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dave P. Quote  Post ReplyReply Direct Link To This Post Posted: 19 Sep 2019 at 14:10
I'm still puzzled about the two apparently purposeless o rings.
Where's Amboman?
TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.

1971 V7 Special. 1972 850GT.
1970 T120 Bonnie. 2009 500 Bullet.
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