Measuring case bore

[florio]

Hi everyone,

I had my engine (2.4 MFI) mostly appart to repair a tiny leak in the oil cooler, and noticed a bit of vertical play in the crankshaft (0.060) while examining the real seal at the flywheel. Since everything was already half appart, I decided to double check the crankshaft clearances and make sure all was ok.

Something has me stumped, though: when I measure the bearings and add the thickness of the bearing, I get to exactly 62.000 - 62.012 perpendicular to the parting line. At 120° (ie at 11 - 5 o'clock), I get something a little larger (62. 070), but not at 60° (1 - 7 o'clock).

So, I tried to check the bore without the bearings, but it comes in too small in most places (-0.030) and too large in one direction (out of round). It seems that torquing the case without the bore causes the case to deform a little more. So my question is how are the bore diameters measured accurately without the bearings? Should I not torque down to spec (I falways ollow Wayne's book on the torquing procedure)? I did not have n°8 installed since I needed the access.

Thanks for any help!

[mikedsilva]

Not having #8 installed will be the main error.

At the flywheel end, you have 2 dowels to align the case. At the pulley end, the #8 bearing acts as the dowel. Without the #8 bearing installed, you cannot use any of the measurements you took.

Install the #8 without the pin, and gently torque the case... if you don't torque the pulley end too much, you should be able to tap out the #8 bearing. Then torque the case to factory spec. Don't forget to install the 2 nuts at the pulley end on either side of the #8 bore.

Use thread lube on all through bolts before torquing.

Now you can recheck your tunnel clearances.

[florio]

Wow, the answer came from all the way down under, what a great forum!

Thanks, will follow this and report back. In the meantime, I will start looking for a competent machine shop just in case.

[targa72e]

You need the #8 bearing for accurate measurement. I believe there is a aircoold VW bearing that is the same external dimension as Porsche bearing but with larger center bore so you can get bore gauge in to measure.

john

[florio]

Thank you all for your helpful replies. I removed the dole pin from #8 and pushed out the bearing once the case was half-torqued. With this, the numbers were much more reasonable, with what appears to be a tendency for closing in of the bore. Thus, the case is now with the machine shop for a bore alignement to ensure that everything is up to spec. Fingers crossed that there is not too much oval deformation.


Case Bore (measured)
1A 61.954
1B 61.935
2 61.980
3 61.946
4 61.933
5 61.955
6 61.957
7 61.942