[s-cars] []s-cars] Flywheel TDC mark

[Tom Green]

I believe there is a difference, but it does not look like a documented factory
change, but rather sloppy work omitting the mark on many of the later engines.
I don’t even know where to place any blame since I don’t know if the flywheel is
attached at the engine plant or later, but my understanding is the mark is not made
until the mechanical relationship between #1 cyl TDC is established with flywheel 
position since this mark is the most precise.  I can only surmise that the worker 
responsible for this retired without training a replacement.

IME, the square marks have no place in timing measurements.  

The little oval mark made with a hand stamping tool and hammer that
seems to be on every rusty flywheel for early models just is not there on
some later vehicles.  Flywheel changes can account for some since a new 
flywheel won’t have a mark, but others are known original parts.  The timing
pins for for the crankshaft timing and speed sensors give the most problems 
now by detaching from the flywheel because the attaching welds were weak.

This causes many to spend some extra time verifying the marks on the front
of the engine and removing the valve cover to match cam sprocket marks and
physical piston position.  

Tom
 
> On Tuesday, Oct 27, 2015, at 09:05 AM,radek at uniserve.com wrote:

> Is there a difference between early and late models urs4 and urs6?  We  
> are doing a timing belt job on my son's 1996 and all we can find on  
> the flywheel are two small square ridges, one a few degrees Before  
> TDC, the other more or less at TDC.  Meanwhile Bentley says it should  
> be a notch marking the TDC, consistent with my experience with other  
> I-5s.  Any clues?  TIA.
> 
> Radek.