I have a 1956 GMC 270 in a 1949 100 truck. I'm glad you guy's spent the time and effort to post what you have done trying to fix your rear main seal problems. This will be the 3rd time I have tried to seal up my engine. The last two seals were the best brand. The first time I decided I didn't need to drill and put the 1/16 roll pin in the rear main cap like they suggest to do. ( every time I have tried to fix the leak was on the engine stand). The seal turned in the groove causing a major oil leak. The 2nd time I followed heir instructions to the T. I thought I would be making it better by putting Permatex ultra black under the seal on both the cap and block. ( WRONG ) The seal turned out of the grove 1/2 inch causing another major leak. I have the engine tron down again and all cleaned up ready to try again. This time my engine Machinist who has been doing this for 36 years said here use the Felpro rear main seal and put it in dry, pack it in the cap and block real good and leave approximately .010 sticking out from both ends. Don't put anything on the ends of the seals or under them. Put some engine lube on the seals and put the crank in. If this doesn't work I don't know what to do next. Just an extra note for anybody out there that is having seal issues. I thought I would be smart and put one qt of Lucas engine oil leak in with the oil. Well the leak got less until the Lucas caused restriction of the oil in the rocker arm assembly causing the intake valve on #2 cylinder to seize up in the guide breaking off the end of the pushrod and causing a major issue. All of the valves have excessive ware on them along with the guides. Ordered all new valves, pushrods, installing new brass valve guides and gaskets. When cleaning up all the parts the Lucas was like honey and hard as hell to clean up. one last thing. I got an email from Permatex and they say to put the Permatex high tack gasket adhesive under the rear main seals to keep them from turning? That do you guy's think? Thanks
