We will probably never know what exactly happened to U-867 as there were no survivors, but sabotage is not very likely as the commander would have certainly mentioned this in the distress signals if he would have suspected something like this. There were several other cases in which U-boats damaged their engines in bad weather, the worst being U-284 which had both electrical engines disabled during a storm in the North Atlantic in December 1943 and had to be scuttled as the crew could not repair the damage. In my opinion the heavy damage to the diesel engines of U-867 was probably caused by a snorkel failure in bad weather, allowing sea water to enter the air intakes of the diesel engines and disabling them as described by BHenderson in his post in this thread. One has also take into account that the crew was probably inexperienced with the use of the snorkel, as this U-boat was only recently fitted with it and they were on the first war patrol.

Best regards
Rainer

Crew member of uboat.net