BMW R50/2 Oil Pans and Ogling

Published Monday, September 2, 2024 by Bryan

My Saturday started with a ride to the hardware store. As I was climbing aboard to head home, a guy maybe roughly my age hopped out of his car, phone in hand. “Do you mind if I take a few pictures?” he asked. “That bike looks amazing!”

“No, not at all.” I replied. “It's a 1968 BMW R50. I just got it back on the road after 25 years in a basement.”

“I don't even have any motorcycle experience. I just like the way classic vehicles look,” he mentioned as he snapped shots from different angles. As I kicked it to life and pulled away a few moments later, I could tell he was shooting video. I'm glad there's a good couple of blocks worth of fuel in the carburetor float bowls, so his recording likely ended well before I sputtered to the side of the road and finally remembered to open the petcock at the edge of town.

When I got home, it was time to start the final bit of maintenance I've had on my list since June. Ever since the smack we gave the R50 while loading it into a U-haul in western Massachusetts, the pan has weeped oil. Not enough to cause concern for the level in the engine, but enough to make a mess on the garage floor. It was time to fix that.

I started by draining the oil, in the usual way by pulling the drain bolt. The ride to the hardware store, while necessary for its own reasons, had warmed the engine up to make sure the oil flowed freely. I'm not sure I really like the look of what came out. There were definitely shiny flakes in it. I know I'll need to pull this engine apart eventually - it's literally "regular" maintenance to completely disassemble and clean it every 30,000mi or so - but this might have convinced me to consider that a little sooner than I might have.

I pressed on to removing the twelve 10mm bolts holding the oil pan on. No effort was needed to remove the pan after that - it was loose before I got the last bolt out. I'm now sure that the loading bump just broke the seal on this old cork gasket.

The inside of a steel engine oil pan. A dirty cork gasket runs around the perimeter. The bottom of the pan is covered in a dark-colored mess, speckled with bits of shiny stuff.
This oil pan is basically the oil filter body, where this sludge would be trapped and hidden in a modern engine.

The pan was covered in a layer of black mud, and the mud had more glitter in it. It was a little concerning that it hadn't just pooled around the edges, or in the troughs, but also directly under the pickup tube. I hope the glitter isn't the result of that mud causing oil starvation.

The circular screen attached to the bottom of the engine's oil pickup tube, revealed where the oil pan was removed. Everything is glossy with a film of dirty oil.
At least the larger metal flakes wouldn't make it through that.

The screen covering the pickup tube is the only "filter" this engine has. Beyond this, the only thing cleaning the oil are the slingers at either end of the crankshaft. I'll only be able to clean those slingers during a full disassembly. I removed the screen, to a gush of oil that had been held in suction behind it. One last mess on the floor, hopefully. I gave it a good clean, made sure the pickup tube was clear behind it, and reinstalled.

I found one other thing interesting about that pickup screen. I regularly marvel at this motorcycle being built before humankind landed on the moon. This bit of maintenance reminded me that even Loctite threadlocker was unknown when the first /2 model was designed. Look closely at the heads of the bolts holding the pickup screen in place. Do you see the piece of metal bent up against the side of the bolt? That's how important bolts are secured all over this motorcycle - by working the nearby metal so that it rests against the bolt head to keep it from turning. The red loctite I used to reinstall the valve cover stud that I stripped out of one side, was completely off the map for this bike's construction. The repair manual makes no mention of the proper installation methods for those studs, so maybe they didn't need threadlocker. Or maybe they were never supposed to come out.

The oil pan, cleaned. It's a fairly uniform dull grey color, with the normal minor patina of use.
Muck and crusty gasket, be gone!

The mud hadn't been difficult to remove from the oil pan, but the old gasket took considerable time and focus with a razor blade. It was hard, somewhat brittle, and fixed on with some sort of sealant - a glue or RTV. Worse, each bolt hole was slightly conical, making a long continuous scrape impossible. This was my fault, as I discovered when reading service instructions for this process. These bolts are supposed to have very little torque applied. “Tighten them 1/4 turn past snug and no more,” is Clymer's advice (emphasis theirs). I had snugged them more than that to try to stop the leak. Once I had the old gasket removed, I spent some time with a brass hammer and a small anvil flattening out those cones.

I reinstalled the pan with a smear of non-setting, non-hardening gasket dressing (Permatex Permashield) on each mating surface. After spinning the bolts back into place, I reinstalled the drain plug and poured 1.75 liters of Valvoline VR-1 SAE30 into the engine. We're heading into Autumn, so I shouldn't need the warmer temperature range of SAE40. Start, warm up, stop, wait, check level, all looked good. No leaks, hooray!

With the afternoon all but evaporated, I decided a proper test ride was in order. I bopped through town and pulled into the local hot dog and ice cream stand. This one is only open during the summer, and does fantastic fried cheese curds.

On a cement picnic table top, a tower of vanilla ice cream covered in nuts and topped with a red cherry sits next to a paper cone of breaded fried cheese curds and a pot of dark red dipping sauce. In the background is an out-of-focus old motorcycle.
Turtle sundae and a packet of friend cheese curds with BBQ dipping sauce.

A few bites into my sundae, an older gentleman ambled over from a nearby table. “What year is your bike?” he asked.

“It's a 1968,” I answered.

He smiled. “In the early 60s I had one like it. A 500cc.”

“That's what this one is. It's an R50.”

He looked the bike over more carefully. “That would have had to have been before ‘62, because I had it before I left … where I was living.” His accent didn't tell me where that was, and I didn't want to start us down a tangent if he wanted to talk bikes. “Does it run good?”

“It does now. I've been fixing it up, and just got it back on the road after 25 years off.”

He smiled again, and shook his head. “I always liked how quiet they made these. These bikes today are just…” He held his hands out in front of him, gripping imaginary ape hangers, and gave the throttle a big twist, as he widened his eyes and mouth in a silent scream. His hands dropped from the bars in a motion meant to sweep the thought away.

I tried to find words to explain how this one is actually my loudest motorcycle, but it all got lost in smiles and nods. “Yeah. I know what you mean.”

He wished me lots of fun, and a short time later I set off for just that. It was a beautiful summer night for another hour of backroads.

A small bit of oil was on the garage floor again in the morning. I checked the bolts - completely loose! Oh right, the Permatex directions said to retighten after cure. I seated them again, and gave them their quarter turn. I haven't seen a drop on the floor since. (And yes, the dipstick says there's still oil in it. 😉)

An old black BMW motorcycle parked in a sun-dappled shady parking lot in front of a lake rimmed with trees and tall grass.
A stop along the backroads to the farmstand to capture the moment the odometer rolled over 17,000 miles.

Categories: Motorcycle