Rope seal leaks - PSA (with pictures)
Posted: Fri May 13, 2022 7:26 pm
TL;DR: If you have had your block line bored and fitted steel mains, check your rear seal carrier to make sure it doesn't hit a bearing cap before it hits the block. And make sure that your seal carrier doesn't have a massive banana in the middle of it.
While I had the transmission out of my Elan last week to rebuild it, since I had the engine out as well I decided to try to fix some of the oil leaks. My engine is a 4-bolt rope seal engine, so I know to expect some leaks from the rear main, but I felt that what I had from that area was excessive, especially because the last time I replaced the rear main (just two years and ~8,000 miles ago) I used a braided graphite type which is supposed to be a superior material.
I do not know how well the seal was still functioning, but a major problem revealed itself once I removed the seal carrier. The sealant pattern (easily spotted when using a certain Aussie's favorite sealant ) on the carrier revealed that part was making very poor, if any, contact with the block and/or paper gasket.
Further examination verified this issue and showed a visible gap between the carrier and block (no gasket in place in photo)
With the facts laid out, now it's time for conjectures: While it's definitely possible that my carrier was dropped/beaten/pried/abused in the past, when I dug an extra out of the pile/hoard and fitted it up, I noticed that there was some light interference between the inner edge of the carrier and the rearmost main bearing cap. When I built the engine two years ago I had the block modified to take steel mains and it appears that the edge of #5 just barely hangs over the edge of the block.
It may be possible that this small lip and the force of tightening the mounting bolts up distorted my carrier. I have my doubts, because I would expect a witness mark on the carrier. Regardless, the bearing cap was still preventing an ideal fitup between my spare carrier and the block, so I filed a small relief in this area.
After adding this relief, the carrier sits flat against the block, as it should.
I was up into the wee hours of the morning yesterday reinstalling the engine and transmission, the car is back on the road now, so I'll know soon enough if this took care of the worst of the leaking.
While I had the transmission out of my Elan last week to rebuild it, since I had the engine out as well I decided to try to fix some of the oil leaks. My engine is a 4-bolt rope seal engine, so I know to expect some leaks from the rear main, but I felt that what I had from that area was excessive, especially because the last time I replaced the rear main (just two years and ~8,000 miles ago) I used a braided graphite type which is supposed to be a superior material.
I do not know how well the seal was still functioning, but a major problem revealed itself once I removed the seal carrier. The sealant pattern (easily spotted when using a certain Aussie's favorite sealant ) on the carrier revealed that part was making very poor, if any, contact with the block and/or paper gasket.
Further examination verified this issue and showed a visible gap between the carrier and block (no gasket in place in photo)
With the facts laid out, now it's time for conjectures: While it's definitely possible that my carrier was dropped/beaten/pried/abused in the past, when I dug an extra out of the pile/hoard and fitted it up, I noticed that there was some light interference between the inner edge of the carrier and the rearmost main bearing cap. When I built the engine two years ago I had the block modified to take steel mains and it appears that the edge of #5 just barely hangs over the edge of the block.
It may be possible that this small lip and the force of tightening the mounting bolts up distorted my carrier. I have my doubts, because I would expect a witness mark on the carrier. Regardless, the bearing cap was still preventing an ideal fitup between my spare carrier and the block, so I filed a small relief in this area.
After adding this relief, the carrier sits flat against the block, as it should.
I was up into the wee hours of the morning yesterday reinstalling the engine and transmission, the car is back on the road now, so I'll know soon enough if this took care of the worst of the leaking.