Ian's951

Hi all,
I am totally rebuilding my 951 engine after a burned valve a few months ago. My first step in the re-assembly process was to install the crankshaft and lower crankshaft section. After completing the crankshaft installation I noticed that the lower crankshaft section was hanging over the front on the block by about 1-2 mm (the rear part is flush). This would make the surface for the oil pump installation uneven! No parts were damaged during the dis-assembly process.

Is this "overhang" supposed to be there? Any advise would be greatly appreciated.

Ian.

xsboost90

did you have the block machined? I know that supras, when u machine the block surface, you must also machine the front cover. You may need to machine some other stuff.

cruise98

Ian:

The surfaces should be flush or very close. This can be hard to achieve.

I stuck the crank girdle in the freezer, installed the oil pump (temporarily), and assembled it that way. The loctite does not like to stick to the frozen aluminum, so apply it to the block. Be quick with the bolt tightening. There is a proper sequence.

The Porsche manual says to use an oil stone to obtain a flush surface. Hmmm...aluminum shavings all over a clean block and new bearings.

Ian's951

No machining was done by me. It is possible that the previous owner had some done though? It must be flush though?

michaeldean

You can just see the missalignment Ian is speaking of.

Cheers,
Michael

Danno

Install a locating dowel on the front of the block & girdle like there is at the back. It's too easy to get mis-alignments when using the bolt-holes and bolts to locate the block-to-girdle interface. Under power, you also get some squirming as well. Which I only can deduce from the bearing wear patterns as I've got no way to dynamically measure the girdle moving around under full-power.

Chris Prack

What you neglected to do was align the two halves after the initial torque step.

If you follow the procedure in the book, the first step is to torque the main nuts to about 20nm or so. Then you need to use a rubber mallet and tap the lower half until the ends are in alignment at the oil pump mounting face.

If it's not; as yours isn't; you need to remove it, clean it up and do it again otherwise it will leak.

Ian's951

thanks for all the suggestions, I did try the rubber mallet route, but the rear locater pin seems to be preventing any rearward movement of the girdle. There just does not seem to be any front to back movement possible to make it flush up front!?