Another U-Seal failure! - M104

[hispassion]

When performing my headgasket repair (coolant corrosion), I found that the U-Shaped seal at the timing cover had split which was causing the oil leak.

At the time, I blamed it on too much silicone sealer in the area causing it split. Likely from a repair of the previous owner.

So, knowing enough not to put any sealer on the seal, I replaced the seal and only put a spot of sealer on the ends where it meets the cylinder head. No leak and I was happy.

Fast forward about 7 weeks. I started noticing a leak coming from the front of the engine and coating the air pump and alternator. However it was leaking at a faster rate than previous. I was expecting something more catastrophic, but not the case. The U-Shaped seal was split again in several places! This time with no silicone.

So, I wonder what could be causing this? If I recall correctly, I think I oiled the seal so I could get the cover on without rolling the seal out of its groove. I suspicion that the oil I used (engine oil) may have been contaminated with solvent and may have caused the seal to expand. Or maybe if memory doesn't serve me correctly, I didn't oil it and the small amount of expansion and contraction of the two covers could have caused the seal to split. In other words, I don't know what could be causing this seal to fail. Pictures below.

This time...


Last time...


Any thoughts?