Mystery oil leak in back of 40 hp motor

[pdb27]

[wdfifteen]

[KTPhil]

If the endplay can be cured by re-shimming the flywheel, you don't need an engine rebuild.
If the bearing itself is loose in the case, then yes, case machining is needed.
_________________
Current Fleet:
'71 Fastback
'69 Westfalia
Retired:
'67 Beetle
'65 Beetle (x2)
'65 Bus
'71 Squareback

[pdb27]

One more update to this thread after getting to know the motor for about 12,000 miles, and after attending several VW shows and speaking with old-timer mechanics possessing enjoyable esoteric knowledge about air-cooled engines.

First, there is likely something going on internally with the old 40-horse that is contributing to the oil seepage past the crankshaft pulley. I have noticed an omni-present ticking in the motor, even after adjusting the valves, and it is coming from inside the case (confirmed by listening on one side, then the other, then underneath, and then with the needle-stethoscope thingy). A couple of the aforementioned VW savants believe I might have too much crankshaft end play, which matches the ticking noise, the oil leakage, and the overall condition of the motor when I bought it from a Formula-Vee racer. Short of a rebuild, it is what it is; nothing I can do until it starts to bleed to death on some future grey day.

Second, I've got the engine to a daily driver condition where the leaks don't trouble me much. Stock air cleaner on top, slightly thicker oil (Royal Purple 15W-40 with zinc), keeping the level to between min-and-max markings, limiting my speed to 60 mph, and watching the throttle on hot days all adds up to a driveable bug. If I had it to do over again I would probably paint the engine black, rather than red, because all those little heat-shedding tricks add up. Red looks great, but for a daily driver I would have selected the plain-but-functional black paint job.

So, that's the cherry on top for this thread, based on all I've learned. Another hat tip to thesamba.com feedback providers, and I hope this helps you future readers.

[pdb27]

I do have a stock oil cleaner, but it's currently not usable because the breather hose opening on the right hand side has been pinched shut. There is a "Volkstoberfest" in Indy on 9 Oct that includes a parts swap, so I'll see if I can't score one when I'm down there. Several threads have recommended using the stock cleaner, and I think it will even help out with my crankshaft pulley leakage, so I'm planning to make that move.

[KTPhil]

Those low profile air cleaners do not give space for the fuel fog above the carb at certain rpms. It can wet the filter element, and even draw oil in from the breather to saturate it, and then it leaks down. Do you have a stock air cleaner you can try substituting? The internal tube acts to hold the fog, and of course it doesn't mind getting oil in its fibers.
_________________
Current Fleet:
'71 Fastback
'69 Westfalia
Retired:
'67 Beetle
'65 Beetle (x2)
'65 Bus
'71 Squareback

[vwoldbug]

Can you look for a small rust hole in the oil filler .

[pdb27]

This morning I finally had the chance to run the bug down the interstate for an hour, and after popping the decklid to take a look ... (drumroll) ... it was dry! Mostly. Dry enough for my expectations. It looks like the culprit was an overfilled crankcase due to relying on an uncalibrated dipstick to tell me when to stop adding oil. Lesson: only dipsticks rely on just the dipstick.

The engine even sounded better while purring down the interstate. I think I'll change the generator stand and fuel pump gaskets one last time to clean those up, and then call it good. Many thanks to the commenters on this thread!

[pdb27]

[cyclehobby]

All the responses from the Samba are excellent possibilities for the cause of your oil leak. But your last post has me intrigued. You said you changed the oil and added oil to put it in the proper spot on the dipstick, but not all the way to the top.

Is it possible you have an incorrect dipstick and you're overfilling the crankcase each time? Too much oil can cause leaks in certain ways. Your oil breather, the crank pulley, the main seal. All can spew oil if there's too much volume and associated pressure. I would think that at high speeds, extra oil slinging around could find it's way out in a number of places.

In my car, I found that filling the crankcase until the highest mark on the dipstick was way too much oil. During an oil change, I put in EXACTLY the 2.5 quarts needed and the dipstick showed oil right in the middle of the low and high marks. I filed a mark right there so I know the right amount of oil is on that spot and I've been very leak free for years.

The rather low oil capacity of these motors also means that when you have a full crankcase and add some sort of oil additive, you're potentially raising the oil level too high. Not sure what to tell you about additives (that may be a separate discussion), but if you've had issues with some of the parts used on your engine rebuild, the dipstick could be the culprit.
_________________
1967 Beetle
Northern NJ

[pdb27]

Quick update on this thread: I haven't yet driven it on the Interstate for an hour, which is typically when the oil leak is most obvious, but I've been watching it closely enough for the last 2 weeks in mixed driving around town to say that the leak is still there. Very low level, but definitely present.

Crankcase oil level does seem to play a role. During troubleshooting I changed the oil and refilled to between the low and high marks on the dipstick, and at that level there was very little leaking. A few days ago I poured in an oil additive that brought it up to the high mark on the dipstick, and afterwards I could see evidence of more oil coming from behind the pulley. I'll drain a bit back out and see if the leak abates.

My intention to try a stock air cleaner with better negative pressure is on pause, because the one I have has the breather port pinched shut and sealed. Not sure why anybody would do that, but I'll try to bang it back open at some point when I have the time.

I haven't put the stock pulley back on because the leak was present with both pulleys, and a visual inspection showed them to both have clean grooves. Maybe later.

Final comment is that the oil appears to be most noticeable on the tin to the right of the pulley near the dipstick, and I've read in other threads that some owners will put string up there to help seal in oil splashing up from the crankcase. I'll give that a go and see what happens.

So maybe this wasn't such a quick update, but the quick summary is that the oil leak persists and I'm learning bit by bit. When the oil leak is addressed I'll add a closing write-up to the post. Thanks again to all commenters for your help.

[Eric&Barb]

[pdb27]

[Eric&Barb]

Clean up the stock pulley, and you can sand the inner bore so it just slides onto the crankshaft. Then install it to see if the oil leak goes away.
_________________
In Stereo, Where Available!

[1960vw]

Another spot , though rare, is from base of distributor, O-ring on shaft going into case. You've checked the common culprits. Hope you find it!

[pdb27]

Took the day off to begin trouble-shooting, with no clear smoking gun yet (that i can tell). Pictures below.

Oil level OK, right under the top line. Took the breather off and ensured it was clear by blowing through it; cut a new gasket and cinched it back on tightly. Popped off the air cleaner top and took a photo of the oil condensate; there wasn't much, but it does appear to be breathing fine. Removed pulley and compared to the stock version - both were the same size and had clean grooves (and both experienced the same leak, so those grooves aren't a likely contributor). Gasket on the cap was very oily, but sealed up fine.

It was difficult to get a good photo of the crankshaft area with the engine still in, but I attached the best one of the bunch. I could not tell whether there was an oil slinger in place, but there was a washer-like thing in there that I could move with a long screwdriver. It looked flat to me, so I can't say whether it's cupping in or out. It is rusty, like many of the old parts my engine builder put on the bug (separate story).

Anybody have ideas based on these pictures? Sand seal is the next step?

[RWK]

Also check that the gen tower to breather/oil filler nut is tight and a gasket is ok.
_________________
73 Type 181
63 Type 113
63 Type 261- 428 071
62 Type 241-378 025 178 530

[pdb27]

[Eric&Barb]

Check that the oil groove in the pulley is not full of dirt or is even there. Some pulleys are are made for sand seal only.

Better to get the stock dog house crankshaft pulley that is bigger for more gen and cooling fan RPMs. That in turn will make the engine run cooler, and last longer.
_________________
In Stereo, Where Available!

[1960vw]

Check the gasket on the oil fill cap. I would also clamp the bypass hose at both from oil neck to air cleaner. Nice looking engine!