If you like our site, please consider joining our club!
By joining you will help ensure that we can continue to provide this service
JOIN HERE!

Oil leak at cylinder base

User avatar
malmac
Posts: 796
Joined: Sun Jun 29, 2014 2:10 am
Location: Toowoomba, Australia.
Has thanked: 1 time

Toowoomba in these troubled times

Post by malmac »

Michel

Toowoomba is a pretty good place to live. Not all of it looks this pretty.

I guess you won't be passing by again anytime soon, but we always have a bed for a BMW rider.

Plenty have stayed in the past and I hope lots more will visit in the future.

Mal
Toowoomba
Queensland
Oz
Attachments
dji_0430.jpg
dji_0430.jpg (145.91 KiB) Viewed 2886 times
mal - R69s
Toowoomba- Australia

Wayne J in MA
Posts: 91
Joined: Fri Nov 02, 2012 8:18 am
Has thanked: 1 time

Leak at base of cylinder

Post by Wayne J in MA »

Any chance that the cylinder may have taken a hit in the past? I have never seen a hairline crack from this but may be possible.
'62 R69S, '71 R75/5 SWB, '78 R100S Motorsport
Westwood, MA USA

corvair
Posts: 7
Joined: Sat Nov 05, 2016 5:58 am

Will have a shop look at cylinder...

Post by corvair »


Thanks, Mal, for the invitation, which I extend to you should your future travels take you to the Canadian Rockies!

Wayne: The bike was leaking when I bought it, not to say it did not take a hit while being shipped across the US by transport. Today I was given the name of a local fabrication shop, who's done work on motorcycles, who may be able to "plug/seal/weld it". I'll remove the cylinder one more time and take it to them in the next couple of weeks.

Wish me luck!

Michel
Michel Gelinas
Calgary, AB, Canada
1961 R69S

User avatar
Beemer100
Posts: 148
Joined: Tue May 15, 2018 5:32 pm

Michel, not sure I would take

Post by Beemer100 »

Michel,

not sure I would take that route. Welding a cylinder, I mean. Punctual heat etc doesn't sound good to me. I would look for another cylinder, original with a good bore if possible. Check with the usual addresses. I would be surprised if you cannot find one.

best regards
Klaus

User avatar
malmac
Posts: 796
Joined: Sun Jun 29, 2014 2:10 am
Location: Toowoomba, Australia.
Has thanked: 1 time

Welding as an option

Post by malmac »

Michael

Given that the hole is not structural, you probably dont need to weld it to seal it.

If you carefully measure the bore at that point in several directions to determine roundness and size.

Then you could clean the bore throughly and try silver solder or brazing. Much less heat and it could be quite effective.
Having made your repair then the cylinder could be measured to ensure no measurable distortion took place.

Is it an option to seal the outside of the cylinder where the oil is exiting.
This might be done with a dril a tapped thread and a grub screw or brazing if the hole is more of an unusual shape..

If all that fails I guess you could look for a replacement cylinder.

Mal
mal - R69s
Toowoomba- Australia

Captonzap
Posts: 87
Joined: Thu Aug 21, 2014 10:24 pm

Since it sounds like the hole

Post by Captonzap »

Since it sounds like the hole is below the compression area of the cylinder, the most pressure differential you can have is crankcase pressure and ambient.
Harley Ableson used to coat the inside of their crank cases to keep them from seeping oil, due to the porous castings.
In this day of modern plastics, here is what I would try. Mark the hole, then purge it with acetone until you think it is clean. Rig a vacuum pump like the windshield repair guys use, and suck JB Weld into and through the hole. Anything that is left on the inside can be cleaned off with a bearing scraper. And the JB Weld is good to 350 deg, which, if you have oil circulating, the plastic should never get that hot.

Or, a round tipped drift, and peen the hole closed.

User avatar
Micha
Posts: 759
Joined: Fri Oct 12, 2007 2:24 am
Location: Israel
Has thanked: 10 times
Been thanked: 4 times

Would a new sleeve transplant

Post by Micha »

Would a new sleeve transplant not solve this issue?
Michael Steinmann
R51/3 1952
Engine Nr. 529466

corvair
Posts: 7
Joined: Sat Nov 05, 2016 5:58 am

Re: Oil leak at cylinder base

Post by corvair »

Gents,

I want to let you know exactly what the cause of the oil leak was and how I solved the problem in case this ever happens to someone else.
I took the cylinder to a welding shop recommended by a local vintage BMW rider. The welder took the paint off the cylinder flange and did a test by putting red dye within the cylinder bore, over the pitted area, to see if/where the dye would travel outward by capillary action. You'll see on the attached photo the dye came out in many places! Evidently, that cylinder flange had been welded before, which was not so obvious when painted. The welder honestly said it would be cheaper/better to find a replacement cylinder. He would have attempted to fix it if this was the only such cylinder in the world but it would have been expensive and "not guaranteed"!
Perhaps I should have had it sleeved but, when I saw the crack in the base flange, I decided to get a new/repro cylinder.
I finally got everything back together a month ago. I had the opportunity to ride the bike 4 times, about 300 miles, and I did not see any leak yet! It is now put to rest for the winter season.
NOTE: The new repro cylinder showed a small pinhole within the bore, near the lower edge. After I got the cylinder bored out to fit my oversize 72.50 mm piston, the pinhole had disappeared! I was thankful it was not a sign of porosity!
IMG_1203.JPG
Michel Gelinas
Calgary, AB, Canada
1961 R69S

User avatar
schrader7032
Posts: 9016
Joined: Fri Oct 27, 2006 3:00 am
Location: San Antonio, TX
Has thanked: 2 times
Been thanked: 29 times

Re: Oil leak at cylinder base

Post by schrader7032 »

Nice work! That's certainly one for the books!
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

Post Reply