OLD MAN SLINGER RANT!!

[sherman980]

I was catching up on some current threads here after having been gone for a month and finally had enough!

"The engine slingers service is a must..." (on a 25K mile bike) - apologies mcsherry1328, this is not directed at you personally, but at the now "11th Internet Commandment" that if not followed, your bike will explode with nuclear furry!

Been working on (as a shop mechanic and hobbyist) and riding /2 and earlier BMWs since the late 60's. As a shop mechanic, THERE WAS NO STANDARD "SLINGER SERVICE"!!! If a bike had a crankshaft issue or needed an engine rebuild for some reason, we would tear it down and clean or replace the "oil throwers" as a mater of course, but I can't recall a single instance of someone coming into a BMW shop (either when I worked at or as customer back in the day) when a service manager told a customer that they should bring their bike in for a "slinger service".

If you look in your period BMW owners manual or service manual, you won't find any recommended "service interval" for cleaning or replacing them. And they are barely mentioned in the BMW workshop manuals of the time other than as part of reassembling your crankshaft for installation back into your motor! Further, if you look at their primary function - throwing oil to the various parts of the engine that need lubrication, they will continue to work even if full of sludge (and they take a LOT of miles with frequent oil changes to fill up). I am NOT recommending that you never address them, particularly in an engine with lots of miles, unknown service history, and an oil pan full of sludge. And if you are doing a ground up restoration, well, standard procedure while the motor is apart. But to scare the heck out of a newbie that if they don't immediately take their new ride apart and spend considerable time, effort and dollars on a "slinger service", they will be left on the side of the road with a melted engine is just bad advice in my opinion. And I understand it is just one guy's opinion at that. That said, BMW used the slinger design for a number of decades and, to my knowledge - I'm sure someone will find a service bulletin somewhere - never suggested taking apart one of their motorcycles just to do a "slinger service".

Oh, and I am not unfamiliar with slinger servicing...

Rant over now. Other opinions welcome...

[R68]

Gee Wizz, and I thought I was the only one who thought that.

[schrader7032]

Seems to me it's one of those peace-of-mind considerations. As you say, if there are questions about actual mileage, service history, etc., and you plan on want to ride worry free, then cleaning the slingers is the thing to do. I wouldn't just do a "slinger service" but be sure and include it as part of a mechanical restoration if the conditions warranted it. I don't imagine it would be a fun thing to be going down the road all the time and say to yourself "I wish I had done the slingers. I wonder if the slingers are OK." In some cases, peace-of-mind might be worth it.

[808Airhead]

In the spirit of “better safe than sorry” I think it is essential on any bike , unless it has receipts/ proof of this being performed. It is much cheaper to address the slingers than it is to ruin a crankshaft. My first bike,a 64’ R60/2 , was purchased from the widow of the original owner with 10k miles , rode it for 7 and at 17k took engine apart, found slingers full, and a rear main bearing surface spun/worn. I was surprised at that mileage to see the wear & tear and am happy I stopped to rebuild it. At the same time the transmission was rebuilt by yours truly and I can now enjoy it and rev it out with no worries! These bikes are such a wonderful vintage mechanical design and quite rewarding to get them built and running well. I will repeat again “my mantra”….whenever purchasing any vintage BMW….. “BE READY TO REBUILD THE WHOLE GODDAM THING!”

[Tinkertimejeff]

I got this factory original Dark Gray (not Bristol Grey) '66 R 50/2 from the original owner with 13,000 miles on it. I pulled it apart to clean the the bike properly and after finding a lot of sludge in the oil pan I pulled the front bearing carrier just to check the front slinger. I ended up doing a complete lower end on it. Both slingers were packed solid, the pictures show the pile of crude I removed.

[mcsherry1328]

My intent was to inform a newbie and others about maintaining a sixty year old vintage BMW motorcycle. If slingers are neglected,ultimately an oil passage will fill and deprive big end of crankshaft of critical oiling.
Years ago these bikes were relatively cheap and engine service wasn’t expensive either. Nowadays slash two BMW’s are selling for over twenty thousand dollars with some even higher. A replacement crankshaft can cost several thousand dollars plus labor of that much as well. My consideration is preventative and if done can deliver many years of dependable service.
I certainly wouldn’t recommend this service if I didn’t believe it to be critical.
Discussion on slinger service has always stirred a lot of comments and there are many on this forum with much more experience than myself.

[niall4473]

I think a major factor here is the length of time in which an engine has been inactive, most motors in those days had some kind of centrifugal sludge trap,( I am thinking of British and other European here), ant they worked ok for the most part.
What can happen, though, is that somebody gets a time-capsule bike out of long term storage, changes the oil for a modern detergent one, and the dried-out sludge in the trap breaks up and blocks the oil-ways, wrecking the engine.
This is not peculiar to BMWs, Triumphs, Nortons, BSAs, Matchlesses, Ariels can all be destroyed in this way.
It is true what McSherry says that they were not fixated over in the day, just done when a crank rebuild was required, but back then the vast majority had been in daily use up to that point, so liberating dried up sludge was not a worry.

[Tinkertimejeff]

I would agree you should not do it just to do it, you should look for signs that the motor should come apart. With the Barn Bike I saved from a trash heap a few years ago it was pretty obvious what caused the initial engine seizure that led to a minor crash and sent the bike into 57 year slumber partially disassembled in less than ideal conditions. If you look at the photo closely that object that appears to budging into view is the front slinger that had heated up to the point it overheated to the point it melted the front bearing carrier and expanded back into the crankcase and stopped the motor. It took two months of work just to disassemble the motor without destroying the block. The bike is fine now and will be enjoyed for many years to come. I think the slinger issue developed as the introduction and increased use of detergent oils in the bikes which kept the internals cleaner but increased the amount of sediment suspended in the oil. Some of the sediment became lodged in the slingers where it built up and eventually became a problem not caused by engine design but by the detergent oil many started using. I don't think BMW would have been motivated to say don't use it or recommend a complete engine overhaul as a regular service.

[sherman980]

Guys,
Step back a bit and take a close look at the oiling system on a slinger equipped vintage BMW engine. A full slinger on its own will not block an oil passage and destroy your crankshaft. If your slingers are "full", especially on a low mileage bike, your engine has other problems that are generating a lot of particles that are getting caught in the slinger, and you were already on your way to a serious problem. Once a slinger is full of these particles, yes, the newly generated ones do get passed along and create even more internal wear, but it wasn't the slinger that created the problem in the first place, especially on a low mileage bike that has sat for a long time.

A bike that has sat for many years with old oil that is never changed in an unconditioned environment and never kicked over or started to circulate the oil from time to time will develop issues. Cylinders, rings, bearings, etc. will begin to rust and corrode (even if you can't see it), and when the bike is put back into use, you will have accelerated wear from the micro (or larger) pitting that has taken place. Sometimes, this can be catastrophic (a seizure, spun bearing, etc.), but with today's improved oils, more often than not, the engine brought back to life can live for a very long time with frequent oil changes.

When bringing an old slinger equipped BMW that has sat for some time back to life, my first step is to drain the oil (through a cloth to inspect for metal or other particles and debris) and then drop the oil pan and see what's there. That will tell you a lot. Black tar with metal flakes are the worst signs - likely time for a full rebuild. If there's nothing terrible found, a good thorough cleaning of the inside of the crankcase with gas or kerosene comes next. Put a magnet in the oil pan, some fresh oil, and if there are no other bad signs at that point, fire her up (yes, check the compression, the valves, the timing, etc.), check for good oil flow to the top end and listen for nasty noises. An oil change after the first 50 miles along with a look at the magnet you had just put in (yes, you get to drop the pan again) will tell you whether to go ride and have fun for a bit or time to take a closer look. If good to go, repeat every 2-300 miles oil for the next 1000 or so miles, and, if no nasty noises or signs, enjoy.

One last note... When working on these bikes when they were relatively newer, it was not uncommon to see a bike with 70K or 90K miles (sometimes more) on it before the lower end was touched. It likely had a top end or two or three by that point, but, with an oil change ever 1000 miles, life was good! And mcsherry1328, no offense intended. Just one guy's opinion...

[sherman980]

Some of you were posting while I was typing the reply above. YES! Do NOT use detergent oils in an old bike being brought back to life! If you want an "11th Internet Commandment", that should be it!