As I described in my build thread, last year, once I got the engine running, I noticed significant oil drops (or more) after each drive. With winter in full throttle, I decided to drop the motor, and see about fixing the leak.

Here's the view of the front. Maybe you can see some oil.

I found some oil inside the inner blowing housing, along the recess for the blower cage.

Starting from the top, the case seam looks OK.

The front seal looks a bit oil wet. But is the seal leaking, or oil blowing from elsewhere?

Lots of oil sitting on the top edge of the oil pump cover.

Quite a bit of oil pooled in the right motor mount bracket, probably dripping from the inner blower housing.

No oil visible where I would expect it if the cooler seals leaked.

Some oil sitting on top of the filter.

Meanwhile, underneath I might have just a bit of oil weeping from the outer pushrod tube seals and/or the valve covers on both sides.

But the inner seals, and the cylinder-to-case joints look dry.

Tomorrow, I will get in closer with more light. Any suggestions and ideas appreciated.

Looking at that black wire on the front of the engine, does it end up reaching up so oil could follow it down to the wire zip ties? I see seepage, at the front seal, but nothing bad. I've had a poorly made oil filter leak and shoot oil out and looked like a cooler leak.

front seal for sure,well be interesting to see why it is leaking,not generally a concern except on a high mileage motor.

you have an aftermarket oil pump, they are very very very hard to seal

We have the same concern with an oil leak in this area, also running an aftermarket pump. Thanks to the good doctor. Why are they so hard to seal? covers not flat/

Thanks everyone. Based on what I see so far, I will replace the front shaft seal and O-ring, after checking the seal surface on the hub, reseal the oil pump cover, and replace the oil filter. Any other ideas?

T1 pumps OD is usually a few thousandths smaller than the T4 OD. This allows some bleed by between the pump OD and the case. That puts all the sealing duty on that thin paper gasket.

I have wondered the same. Is this an application for a gasket in a tube? very sparingly of course.

Is there a doctor in the house?

No. It’s an application to use the proper T4 oil pump (with a pinned or peened idler shaft).

T4 pump OD is 2.7565” using a smaller OD T1 pump and gasket in a tube is just a cobble job in my opinion.

I used a Schadek 26mm pump on a recent build and I suspect an oil leak at the cover. Not sure what is the OD of these pumps.

Bob, It makes some sense to replace the oil seal and O ring, but this is a difficult/tricky diagnosis.

I see oil at the top of the case on the right side under the filler chimney. Make sure the seal for the filler assembly to case are properly installed. I glue the cork rectangle to the metal "box" with 3m weather strip adhesive. I think there is also an o-ring at the base of the filler neck/metal box.

OK, what is the proper pump choice in 2023?

There are plenty of usable T4 pumps floating around still in good shape. Unless the stock T4 pump ingested shrapnel or pumped abrasives like rust, oil pumps don’t really wear much. The main issue with T4 pumps is potential for movement of the idler shaft if the engine is over heated. This can be remedied by peening or pinning the idler shaft to the T4 pump body.

I’m well aware this flies in the face of others that use and recommend T1 pumps. They “work” in the most generic sense. I get it, T4 pumps aren’t being made in mass and can’t be purchased new. Well, there are some CNC billet versions being made in Germany but unfortunately those are expensive and have 30mm gears which is overkill for a stock engine.

The problem from an engineering perspective is T1 pumps don’t fit properly. At best, they are prone to leak. At worst they compromise oil pressure when the OD is too small and bleeds oil out between the case and the pump body right back to the sump.

Wasn’t that long ago this happened to another member on the forum suffering from warm oil pressure issues until he swapped the problem T1 pump for another T1 pump that had a couple thousandths larger OD closer to what the T4 oil pump is.

Honestly, it’s a choose your poison thing. Take the time to find a good T4 pump or deal with T1 issues.

I’m not suggesting you change your pump given it’s what you already have and have probably tossed the stock T4 pump.. But as others have suggested, it may be contributing to your oil leaking. It’s a catch 22 because if you pile in more gasket sealant or try to stack paper gaskets behind the steel cover - it increases internal pump bypass resulting in lower output pressure. Especially so if someone were to try to use thick stuff like RTV as sealant.

Probably the best thing you can do is clean up and dry what you have. Make sure the mounting surface where the pump mates to the case is flat, smooth and sealing properly. Address the front seal while you’re in there. Then use some UV dye in the oil when you fire it back up. Immediately watch that are as best you can and after the 1st drive to see if it’s still leaking and where it’s coming from before it gets to blowing around too much. Visibility in that area sucks with the fan shroud installed - I get it.

I think you have oil going in the direction of the yellow arrow - collecting at the blue stand off and dripping down to the motor mount via the zip ties. It also drips down the black wiring and drips toward the center of the engine.

I don’t think the front crank seal is all that wet to be running down to the blue area. The tell would be if there is a stream of oil in the valley the red arrow is pointing to. From what I can see, I think the red valley is pretty dry.

If it’s coming from the oil pump area via the yellow route. Then I think it’s worth checking the gasket between the case and the oil pump. What is the thick wet looking black stuff? (Purple arrow) Is that a paper gasket or is that RTV between the pump body and the case? RTV won’t be enough to hold back pressurized oil that is between the T1 oil pump OD and the case ID.

The head scratcher is where did the oil in the filter top come from? Is the oil filter tight enough?

Click to view attachment

Is it possible to have a Wobble in the Crankshaft?
If so, could it cause the seal to have blow-by?

It is possible, but you would feel the engine shaking itself apart.

My two cents from my experience here: http://www.914world.com/bbs2/index.php?showtopic=354879

I thought I was very thorough sealing the T1 pump and cover to the case when I replaced it last year. I don't have an OP gauge (I probably should have one) but seemingly had no issues, and the oil leak was gone. Last week I changed the oil, however, and I did see signs of oil collecting at the bottom of the cover again. Not to the point of slinging oil around, or as bad as @bkrantz has here (yet) but still frustrating

Until I read this thread I didn't know that the OD of the T1 pump is undersized. I think @rfinegan was inferring that in one of his posts earlier in my thread, but I don't think I picked up on it. On the plus side, I do think these sealing nuts likely helped reduce, if not eliminate, the leaks: https://vwparts.aircooled.net/8mm-Self-Seal...111-115-161.htm

Bottom line: yeah, it seems these T1 pumps are very very very hard to seal, as George pointed out. I'll consider swapping it out for a serviceable T4 pump next time engine is out.

On a side note, I remember going down a rabbit hole on the Samba WRT the intense debate over advantages and disadvantages of 30mm pumps vs. 26mm. After reading that I seem to recall wishing I'd gone the 26mm route...

If your oil pump cover was leaking, oil would be dripping from the bottom of the cover. Make sure the steel cover is perfectly flat. Get a sheet of glass and place a piece of 400 grit wet/dry paper face up with a little oil and lap the surface of the cover until it is perfectly flat. Then finish off with 600 paper. use a thin paper gasket and NO sealant! Torque to spec.

More thanks, everyone.

During assembly, I used a skim of case sealer on all surfaces and gaskets. There is no RTV anywhere. The black line under the pump cover is actually a fiber gasket that came with the pump kit.

The termostat, pulley bolt hole is NOT blind- and can leak a big quantity of oil
in your photo the pulley appear corectly in place BUT a control can be easy to do

OK, more info. And in my quest for the right answer, I embrace all shame and reveal potential stupid.

I took off the blower hub. The area behind the flange actually looks dry.

I confirmed this by running a Qtip around the base of the flange (on the engine side). A but of dirt but no oil. I assume if oil leaked past the front seal, this would be wet.

First stupid: when I went to unscrew the oil filter, it was barely tight. I mean, all it took to start unscrewing it was gentle finger grip.

No obvious leak point around the pump cover.

No leaks around the studs.

Here's the cover off. No dramatic scoring. Also no gasket. I am trying to remember if I did this on purpose. Stupid #2?

And the pump itself.

BTW, if I need to pull this, any clever way to extract it from the case?

I have the same oil pump cover and it was farrrr from flat out of the box. Took me an hour of wet sanding it on glass to get it flat. If you need to pull the pump, one of these works well. Just go slowly or the t-bar bends…
https://www.amazon.com/Puller-Aircooled-Mot...bf6a&nodl=1

Great news!
Nothing crazy

No gasket, but it does appear some residue of a sealer. When she was running how was the oil pressure, cold and hot? What pump is this?

But perhaps pretty dumb.

As best as I recall, I used a thin skim of case sealer (Loctite 574). The pump is a 26mm Shaded, modified (from Aircooled.net).

I only have a oil pressure warning light (something I plan to correct while the engine is out). All I can say is that the light went off quickly after both cold and hot starts, and never came on at idle.

Is there a slot in the body and cover for an o-ring on the pump?

Loose oil filter will spray oil everywhere…

No, the cover has a flat surface.

I sure hope the leak was my pure stupidity, first in not tightening the filter, and then in not checking it before I dropped the engine.

The fan tends to suck in and redistribute oil all over that side of the motor. Most of my experience is with type 4 powered buses where the fan is at the back, but I think the power of the fan is more intense than any air flowing by. The most common leaks are pushrod tube seals. You wouldn't think that oil all dripping from the area of the bottom of the fan would be from there but my experience with ultra violet dye says that's where it comes from most of the time.

People will argue that viton seal will work dry, but that hasn't ever worked for me. The best thing I've found is a bit of ultra black silicone on them, but even with that, it's only a matter of a few months and it starts to leak again.

Thanks, everyone. Going back to my build thread.