Sunday, July 29, 2007

Crankcase Fasteners

A couple of times of year, usually in the summer, I receive a message from an angry young man trying to dismantle a Volkswagen engine. In many cases he has resorted to chisels or screwdrivers; in one case a wedge for splitting firewood was used.

The engine is junk, of course. Which is okay because it is a stupid engine anyway (he sez).

Amazingly, in a few cases it is a Group Letter. The Mechanic-in-Charge has sought advice from a gaggle of friends, all of whom agree there is something wrong with this crankcase.

What's wrong is that the fellow has failed to remove all of the fasteners. Or they have left the oil pump in place. Or perhaps the sump plate. But nine times out of ten, suggesting that might be the cause earns me a nasty-gram, often larded with profanity.

I add the fellow to the Kill File and get on with my life.

I'm sure no one reading this has ever forgotten to remove the oil pump before trying to split the case. And I'm sure no one has ever overlooked the stud tucked under the #1 cam bearing. But you may want to print this out, just in case you ever run into someone with a seriously stuck crankcase.

Be sure to mention that they must remove both the oil-pump cover and the oil-pump itself. If they don't have a pump puller then they may elect to remove the oil-pump studs, or at least two of them, so long as they come from the same side of the crankcase. The same applies to the sump plate in that both the sump plate and the oil strainer must be removed.

You will note there is one stud anchored in the right-hand case-half. (With Volkswagens orientation is always relative to the vehicle. That is, the front of a VW engine is where the flywheel is attached; the fan pulley is on the rear of the engine. In the same vein, the #1 Main Bearing is the one nearest the flywheel. Ditto for the cam bearings. These are the conventions established by the designer of the engine seventy-five years ago and apply to the thirty-million or so Volkswagen engines manufactured since. ) So make sure they haven't overlooked the odd right-hand stud tucked away behind the distributor.

Then there are the three bolts. Sometimes the engine is so clotted with dirt and oil that the lower bolt nearest the flywheel gets overlooked. Have them dig around until they've found and removed all three.

The six M12 studs are difficult to miss but sometimes they fail to remove the washers. In rare cases a washer can jam the threads and hold the case halves as if they were still bolted together. So have them lay-out the six large nuts with their large, thick washers.

Then there are the twelve nuts & washers for the remaining studs, including the odd-ball righty. The one most often over-looked is the one below the #1 cam bearing, which is often completely concealed beneath twenty years of poor maintenance. Make sure they chip away the grunge and remove the hidden nut and its washer.

If the fasteners are neatly arranged on a piece of newspaper it makes it easier to tell if you've found them all. Another good check-off is to physically touch the location of each stud as you count them off.

Once all of the fasteners have been removed along with the pump and sump-plate I prefer to split the case using only the strength of my hands. This isn't as difficult as it sounds, assuming the case isn't fitted with shuffle-pins. Simply grasp the opposite ends of the case at the opposing 'corners.' That is, one hand is positioned near the upper tranny flange, the other under the oil pump. Volkswagen has provided pads in those areas to allow the case to be 'started' with a rubber mallet but if you fiddle with it you'll see you can bring your thumbs to bear against the pads while your hand bears on the other half of the case. By applying pressure alternately you can 'walk' the case apart.


(Note: I've uploaded the drawing above to the engine archive on the Chuggers Group. The drawing is in it's native format [ie, DeltaCAD] meaning it may be manipulated as required. The drawing isn't especially accurate but it's more than a guess :-)