Rope Seal Distress
Posted: Thu Apr 19, 2012 4:16 pm
Not a question, just a story.
After living with oil leaks, not seeps but actual leaks, for over 5,000 miles of driving over the past year, I decided enough was enough and pulled the engine for a complete reseal. Now I know that no twin cam engine is fully dry, but I had a vast gap to cover to tolerable. After replacing the front crank seal and adding an oil slinger that was missing I had confidence that things would be better there by far. At the back of the engine we replaced the rope seal and couldn't get the rear oil seal housing on because the new seal was so much thicker than the tired old one. Anyway, we had to loosen the main caps to get the rear oil seal housing on and then tighten the main caps to compress the seal enough.
Finally after putting all the bits back (with a detour for a fuel pump rebuild and a lot of "two steps forward one step back") it was time to turn the engine without plugs to build some oil pressure before firing it. Double check everything and it all looks OK. Turn on the battery switch, twist the key and...clunk. The starter engaged but just made a sickening clunk. Ahh..duff battery? No. Starter in wrong? No. Then what?
My friend Roy Poague who was so helpful and has built two racing Sevens that are meticulously prepared, said the rope seal was binding on the crank and just needed a bit of break in. I challenged that by saying, "How can a quarter inch wide seal around a polished crank journal create that kind of force?" We tried to turn the engine with a long handled socket on the front crank bolt. No joy. We put it in fourth gear and tried to turn it by pushing the car. The only thing that happened was the tires squeaked on the polished floor. We then tried rolling it forward down a slight grade and dumping the clutch. It turned, but only a bit and brought the car to a halt as if the brakes were on (they were not)!
Roy decided that the only way to get it to move was to tow it down the block and back in gear and let it break in a bit. So, plugs out, fourth gear, twenty miles an hour I was towed down the street chugging like an old Model T Ford. Got oil pressure and things seemed to smooth out. Try it again with plugs installed and switch on halfway down the block. She fires!!
IT'S ALIVE. My relief was palpable and when I got back to the house, I started it on the key quite easily. At last I could breath.
My point in this post is to make others aware of the powerful effect a new rope seal can have on the ability of the crank to turn. If I had not experienced it I never would have believed it myself. Oh, and not a drop from the engine or transmission whose seals we also replaced. Now I'm happy and it was worth it.
After living with oil leaks, not seeps but actual leaks, for over 5,000 miles of driving over the past year, I decided enough was enough and pulled the engine for a complete reseal. Now I know that no twin cam engine is fully dry, but I had a vast gap to cover to tolerable. After replacing the front crank seal and adding an oil slinger that was missing I had confidence that things would be better there by far. At the back of the engine we replaced the rope seal and couldn't get the rear oil seal housing on because the new seal was so much thicker than the tired old one. Anyway, we had to loosen the main caps to get the rear oil seal housing on and then tighten the main caps to compress the seal enough.
Finally after putting all the bits back (with a detour for a fuel pump rebuild and a lot of "two steps forward one step back") it was time to turn the engine without plugs to build some oil pressure before firing it. Double check everything and it all looks OK. Turn on the battery switch, twist the key and...clunk. The starter engaged but just made a sickening clunk. Ahh..duff battery? No. Starter in wrong? No. Then what?
My friend Roy Poague who was so helpful and has built two racing Sevens that are meticulously prepared, said the rope seal was binding on the crank and just needed a bit of break in. I challenged that by saying, "How can a quarter inch wide seal around a polished crank journal create that kind of force?" We tried to turn the engine with a long handled socket on the front crank bolt. No joy. We put it in fourth gear and tried to turn it by pushing the car. The only thing that happened was the tires squeaked on the polished floor. We then tried rolling it forward down a slight grade and dumping the clutch. It turned, but only a bit and brought the car to a halt as if the brakes were on (they were not)!
Roy decided that the only way to get it to move was to tow it down the block and back in gear and let it break in a bit. So, plugs out, fourth gear, twenty miles an hour I was towed down the street chugging like an old Model T Ford. Got oil pressure and things seemed to smooth out. Try it again with plugs installed and switch on halfway down the block. She fires!!
IT'S ALIVE. My relief was palpable and when I got back to the house, I started it on the key quite easily. At last I could breath.
My point in this post is to make others aware of the powerful effect a new rope seal can have on the ability of the crank to turn. If I had not experienced it I never would have believed it myself. Oh, and not a drop from the engine or transmission whose seals we also replaced. Now I'm happy and it was worth it.