puzzled!

hi guys,
I'm currently busy with my first engine out job on my '87 328.
inital reason a suspected oilleal of the frontcamseal.

Getting the engine out is also for me a good job to get more familiar with this engine. Working on my own cars for 25+ years I feel quite capable to do this work. However this is the first time on a ferrari (YES!)

Currently the engine is out. The job is getting into so more work (HUHHH) although this former garage queen turns out to be a pleasure to work on. Not a single rusted part ands most of the engine looks. besided lots of oil-dirt everywhere, as new.

As said. started to replace the camseals i did (obviously)decide to do some more. On the list now are the distribution, the valve clearance, sparkplugs, all filters, all fluids, replacing of the front bearing of the drive pulleys (I actually just yesterday ordered this nice sykes pickavant set to pull the bearings), front and rear crankseal and some clutchwork. I might have forgotten some..

but now I came across something that i do not understand:
working on the front bearings of the drivepulleys is noticed movement of the drivesprocket on the crancase. This sprocket apearently in not fixed axial on the crankcase but is allowed to move. This is oke with me but the real questionmark came when i noticed when pulling the frontcrank seal that this seal seals of on the collar of the drive sprocked and NOT on the crankshaft. Now i'm am puzzled: as this sprocked slides over the crankshaft there seems to be an possible oilleakage there. There is/seems no seal between the sprocket and the crankschaft.

How is oil prevented from slipping through?

all advise appreciated

 

My 308 workshop manual (do you have a manual for your 328?) shows this to be the case and the cam sprocket nose is definitely sealed by the seal.

If the sprocket slides back-and-forth, it shouldn't - the harmonic balancer squeazes it against the crankshaft main bearing portion. The harmonic balancer must not be seated fully against the cam drive gear then...

 

Peter, thanx,


i was maybe not complete in my statement. I have the harmonic balancer of now and than the sprocket can be moved now. I'm pretty sure if the balancer is on this will keep the sprocket to its place. as said i left that for being like it is. What puzzled me is that there appears to be no kind of oilseal other than the one sealing of the cone of the sprocket. This allows, at least i thing i does, oil to slip through the sprocket-sleeving-over the crankshaft causing leaks.

i looked at different manuals but there is no seal or other means to prevent this. Or do i overee something still..

 

You're correct:
The damper ensures the cam drive gear has no axial movement when the damper is tightened.

Yes,there's no seal for the mating seam between the cam drive gear and the crankshaft.

However, you're wrong: IT DOESN'T LEAK.

I hypothesize that the reasons a seal isn't needed is some combination of:

- The fit between the gear's end & the crankshaft is very precisely machined, and is tightly compressed when the damper bolt is torqued down.
- There's no pressure to force oil thru the seam.
- The seam has no motion to drag oil along it.
- The seam is long enough so that surface tension retains the oil.

 

Don't question it too closely or they all might start leaking on us!