Another project, Mismatched case halves, yeh or ney?
09-11-2017, 01:30 PM
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Another project, Mismatched case halves, yeh or ney?
I have a '04 3.6 996 engine to rebuild, long term over the winter project.
The engine was a stock rebuilt (not by me) and the chap only got about 50K miles (70K kms) before a IMS failure. The case looks good with just a minor scrape from the OD of the IMS gear. Wiped out the IMS shaft, busted the 1-3 scavenge pump and the tension guides, but overall looks like a just in time shutdown.
It had slight weep at the IMS and 4-6 head scavenge pump but the rest "looked" good. Scored cylinders 4-6, but I don't think that was IMS related.
In talking to him yesterday he said in the previous rebuild one half of the case was replaced.
Being from aircooled roots this is a total no-no, but he said he asked and several peeps and another shop and they told him this was an accepted practice on the 996. I assume it was replaced do to issues with the 4-6 side cylinders.
I realize that the 996 has a crank carrier, so the bearing saddles are independent of the case.
LN said they have heard of this but can't recommend it.
I already pulled the alignment dowels I could replace them to check sealing surfaces.
Just wanted to ask the collective's and Jake's view of this practice and if it's acceptable or not?
I know my opinion but would like to hear yours and the reasoning.
I don't want to put big bucks into a junk case.
The engine was a stock rebuilt (not by me) and the chap only got about 50K miles (70K kms) before a IMS failure. The case looks good with just a minor scrape from the OD of the IMS gear. Wiped out the IMS shaft, busted the 1-3 scavenge pump and the tension guides, but overall looks like a just in time shutdown.
It had slight weep at the IMS and 4-6 head scavenge pump but the rest "looked" good. Scored cylinders 4-6, but I don't think that was IMS related.
In talking to him yesterday he said in the previous rebuild one half of the case was replaced.
Being from aircooled roots this is a total no-no, but he said he asked and several peeps and another shop and they told him this was an accepted practice on the 996. I assume it was replaced do to issues with the 4-6 side cylinders.
I realize that the 996 has a crank carrier, so the bearing saddles are independent of the case.
LN said they have heard of this but can't recommend it.
I already pulled the alignment dowels I could replace them to check sealing surfaces.
Just wanted to ask the collective's and Jake's view of this practice and if it's acceptable or not?
I know my opinion but would like to hear yours and the reasoning.
I don't want to put big bucks into a junk case.
Last edited by Mark Henry; 09-11-2017 at 01:58 PM.
