R69S Oil Leak

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miller6997
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Joined: Fri Oct 27, 2006 3:00 am

R69S Oil Leak

Post by miller6997 »

I'm getting more oil than I like on the little tray on the back of the engine casing. Every time I look, there is a couple of tablespoons there, and when I clean it off, it begins to reappear after a hundred miles or so. Unfortunately, I have clean Amsoil synthetic in both the engine and transmission, and I cannot for the life of me tell the two lubricants apart by smell or viscosity. The leak is not enough to cause a dramatic change in oil level, so I guess I could ride until the engine oil is nice and dirty and perhaps rule it either in or out that way. With synthetic, that could be a long wait --beyond my usual service interval.

To put this in context, about 15,000 miles ago I had the bike apart for slingers and general inspection and new seals were installed in both units --Ted Porter did the work-- so to my thinking this leak shouldn't be happening. Looks like another bit of work faces me in the near future.

I guess I'm not really asking a question, but any thoughts will be appreciated.
Jon Miller
'67 R69S
'13 F800GT
Altadena, California

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schrader7032
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Joined: Fri Oct 27, 2006 3:00 am
Location: San Antonio, TX

I had my bottom end

Post by schrader7032 »

I had my R69S bottom end overhauled with new seals. I did not change the seals in my transmission, though. I'm running BMW dino oil in the engine and a hypoid gear oil in the tranny (not sure if it's any kind of synthetic). I am also getting some oil on the shelf under the engine. I called the mechanic who did the work and he said it is sort of typical given the pressures inside the engine. I noticed it more after a long trip to Vech's and back. Likely the running for hours at speed pushed more oil out than when I putt around locally. I'm "living with it" for now...if for some reason I need to go into the clutch area, I'll do some more investigation.

The only way to know for sure would be to have some analysis done on the oil or to just go ahead and pull the transmission. Then you would know where it's coming from. I wonder in my case if the area that the seal rides on at the back of the crankshaft might not be a bit rough, thus causing the deterioration of the seal and the leak. It's something of a pain to remove the transmission, requiring serious torque to undo it. I'm thinking I'm going to just let it ride for now.

What about switching to a dino engine oil for a while? In the early days of synthetics, I had heard they didn't use the right seal-swelling compounds which resulted in a lot of leaks. Possibly a change might help your situation.

What's the engine compression...did you do a compression test or leakdown test? Have you had the top end redone? Could it be that you are getting some excess blowby if the rings are not seating or the gap is too wide? Excess blowby might also show as oil mist or vapors at the engine breather port at the front of the engine.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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arthur
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Hello, First post here, not

Post by arthur »

Hello,
First post here, not sure if that's the right place to introduce myself... Anyway, I'm located in France and own a 1969 R60/2 since 1978. This is my 4th /2 bike, if I include the R26 which started it all.
This machine is a 12V alternator model, with Meier 24 liters tank and dual seat. I fitted stainless steel exhaust and pipes found in England, which you can tell just by the look of the pipes! Apart from this it is quite original.
I'm interested in this excess blowby thing, which my bike seems to suffer from. I redid most of the engine (bottom and top end) about 1800 miles ago. Since then I have the same oil leak Jon is talking about, plus one at the front, behind the alternator. Oil leaks from the engine breather too.
All in all that's not a major problem, and I guess I can live with it, but I'm curious to learn more about the excess blowby: where does it come from, and is there a possible cure? A simple one I mean! Thanks.

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schrader7032
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Location: San Antonio, TX

Blowby, in my definition,

Post by schrader7032 »

Blowby, in my definition, will be the combustion gases that are getting by the rings and into the engine cavity. This excess pressure has to go somewhere. There's always going to be positive pressure when the pistons are moving from TDC to BDC...no getting around that. That's what the breather is supposed to help with. Anything more, and the pressure has to find an outlet, which ends up being oil seals, pushrod tube seals, cylinder base gaskets, etc.

The way to check is to do a leakdown test. You can google that and find out what it is and possibly make one. I ended up buying a pretty decent device from Harbor Freight here in the US. Basically, what you're doing is bringing one of the cylinders to TDC on the compression stroke so that both valves are tightly closed...this is all with the engine NOT running. Then with a spark plug adapter, you plug into the cylinder and pressurize the chamber. A good leakdown tester will then tell you what the percentage of leakage is. If there's no leakage past the rings or valves/valve guides, then the percentage is 0. If it's going past the rings, it will some number which is calibrated to be the percentage of what's coming in through the spark plug hole. Around 5% is probably pretty decent...could even go down to near 10% and be sort of OK. The engine must be at or near operating temperature for this.

Without the measurement numbers, you can listen for where the air is leaking. If you go back to the exhaust pipes and hear air, it's the exhaust valves. If you pull off the carb for that cylinder and hear air, it's the intake valves. If you pull the oil dipstick and hear air, it's the rings.

That's the basics. This is something that should be done before a teardown in order to know what to look for during the teardown.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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arthur
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Joined: Wed Dec 15, 2010 6:28 am

Thanks for the tips. Will do

Post by arthur »

Thanks for the tips. Will do an evaluation... when I get a compressor, which is just a matter of a few months.

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miller6997
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Thanks, Kurt. I know this is

Post by miller6997 »

Thanks, Kurt. I know this is a common occurrence for a /2. My brother worked in the dealer's shop in 1967 and he was the one who took this bike out of the crate when it was brand new. He rode it for the first fifteen years or so, so it's definitely a known quantity. He is one of those who says that most /2s have some such leakage and insists that I should just get in the habit of wiping it off and keeping an eye on the levels. As long as it is minimal, he says, it's a minor nuisance, not a problem. I'm a little too obsessive for that, and maybe I'm expecting too much.

Next time, I think I'll get the fugitive oil off the tray with a syringe and put it alongside samples of Amsoil engine oil and transmission lube. That way, I should be able to tell which it is and decide how to go from there.

The bike had new rings when the slingers and seals were done, and the heads were rebuilt with new valves. That was at around 57,000 miles, and I just turned 73,000. Everything seems OK: smooth running, good compression, good performance, and zero smoke. So I don't think I have any real engine problems. I get a little oily residue around the breather port, but never enough to suggest any real issue.

Jon
Jon Miller
'67 R69S
'13 F800GT
Altadena, California

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Darryl.Richman
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If it turns out to be a leak

Post by Darryl.Richman »

If it turns out to be a leak from the transmission, that may be more than just a minor nuisance. When the oil leaks from that direction, it has a much greater possibility of contaminating the clutch. (The flywheel is solid as it faces the rear main seal, so engine oil is very unlikely to make it around to the back side of the flywheel where it could get on the clutch.)
--Darryl Richman

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miller6997
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Good point, Darryl. I'll

Post by miller6997 »

Good point, Darryl. I'll continue with the diagnosis of the oil in the tray.
Jon Miller
'67 R69S
'13 F800GT
Altadena, California

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miller6997
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Joined: Fri Oct 27, 2006 3:00 am

More on that oil leak

Post by miller6997 »

Deciding whether oil is coming from the engine or transmission is devilishly difficult if you have Amsoil in both places. They are both very pale in color and slippery between the fingers. I poured out a small sample of each today and in the picture you can see the comparison. The engine oil (on the right) is slightly darker and, surprisingly, thicker feeling than the gear lube. The gear lube actually flows much more readily than the engine oil.

Now I'll have to wait until enough accumulates on the tray that I can finally determine which it is. My strong hunch at this point is that it is engine oil, in which case I'll just keep an eye on the levels and leave things be for now.
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Jon Miller
'67 R69S
'13 F800GT
Altadena, California

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RainyRider
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Joined: Fri Jun 12, 2009 12:25 am

Oil leak...

Post by RainyRider »

I had that problem when I first got my R-50....I think I replaced the transmission input seal...I should remember, but I've slept since then....

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