Full Version: How can I tell if a case has been line bored?
I am in the market for a new case. Is there an easy way that I can have somebody check to see if a case has been line bored? I cannot have the person take it too a machine shop so are there any telltale signs of a previous line bore?
Every line bored case I have seen is stamped with the numbers on it-.020,.040 for the oversize OD bearings you must use. I have seen it near the dizzy or on the breather tower flat spot or the flat spot on top where the 1.7 engine number is.
You can't do it with a visual inspection. You would have to inspect the case's mating surfaces as well, but even then there may be no way. You'll find several possible conditions.1. Never align-bored: The crank-bearing bore (OD) is unevenly worn, but reasonably close to std. diameter, regardless of the bearing ID.
2. Align-bored: You'll find an oversized OD.
3. Align-bored with the case mating surface milled: The crank bearing OD will almost certainly be back to std. unless it was bored to a specific oversized bearing set based on availability. Regardless, the cam journals will have been re-bored as well.
To check the bearing bores you take the case halves apart, put them back together and torque them to specification, and use a bore-micrometer to measure the crankshaft bearing bore diameters.
Bore mic's are very expensive so most folks don't have them. My dial-indicator bore mic's were about $600 - $700 each.
Good luck
QUOTE(pcar916 @ Dec 16 2010, 08:33 AM) 
You can't do it with a visual inspection. You would have to inspect the case's mating surfaces as well, but even then there may be no way. You'll find several possible conditions.1. Never align-bored: The crank-bearing bore (OD) is unevenly worn, but reasonably close to std. diameter, regardless of the bearing ID.
2. Align-bored: You'll find an oversized OD.
3. Align-bored with the case mating surface milled: The crank bearing OD will almost certainly be back to std. unless it was bored to a specific oversized bearing set based on availability. Regardless, the cam journals will have been re-bored as well.
To check the bearing bores you take the case halves apart, put them back together and torque them to specification, and use a bore-micrometer to measure the crankshaft bearing bore diameters.
Bore mic's are very expensive so most folks don't have them. My dial-indicator bore mic's were about $600 - $700 each.
Good luck
Try going to your local independent Porsche-VW shop and seeing if they some old bearing you can have. If you get Std outers, stab them in the case and question and they are loose, it's probably been line bored. Obviously this is a pretty rough check. Here is a link to a tool which they make for T1 motors http://www.energyonemfg.com/product.php?pr...at=2&page=1
I'm not sure if they make one for T4.
Unfortunately your best option is to work with a supplier who is capable of checking and confirming the case. You can call a local VW Machinist, Soren Andersen (707-542-7872), and see what he's got. He can check the cases out before shipment to tell you exactly what you'll need. You'll pay a little more, but you can get a case that's completely checked and ready to use. No surprises, no machine work necessary.
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