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EFV-8 Club Forum / General Ford Discussion / 1937 engine lower main seal

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Posted By Discussion Topic: 1937 engine lower main seal     Hoppys36 05-23-2019 @ 10:34 AM reply profile send p.m. Member Posts: 3 Joined: Dec 2018 I am having my 1937 engine rebuilt. I purchased the engine in pieces not assembled. The lower rear crank main seal 78-6336 does not fit the main cap. Not sure if it is meant to fit. Is there version that does not use the lower seal. Worried about oil leak. Before pan is installed would appreciate some guidance. Thanks 37RAGTOPMAN 05-23-2019 @ 1:50 PM reply profile send p.m. Senior Posts: 1992 Joined: Oct 2009 HI willing to help, I would like to see a few photos, of the cap and the crankshaft, is that seal aluminum. ? I am thinking one goes in the block and one in the bearing cap , both pot metal or aluminum? there are no rubber seals listed in any of the catalogs, only from 1939 and up hope this helps, 37RAGTOPMAN be sure if there is one in the block remove before having the block hot tanked, it will melt for sure,! supereal 05-23-2019 @ 1:55 PM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 When installing the rope seal, soak it in motor oil well before installation. Use the seal without trimming it. When the pan is replaced, the ends of the seal will be pushed into place, increasing the pressure of the seal against the crank. If you trim the seal, you are guaranteed to more than the usual seepage. Hoppys36 05-23-2019 @ 5:01 PM reply profile send p.m. Member Posts: 3 Joined: Dec 2018 Actually pan is now installed. Only top seal was used and is in the block. Engine on hold for installation until we are sure it is ok to proceed with only the top seal. The bottom seal would not fit in main cap without distortion to point of breaking cap. It seems the cap is not meant to have the bottom seal. I have read that 1936 to 1937 transition some had the bottom seal others not. I’m looking for someone who has experience with an engine which is functioning with only the top seal? We are not adverse opening up the engine and try something else. I’ve attached catalog photos of the top and bottom seal. carcrazy 05-23-2019 @ 6:01 PM reply profile send p.m. Senior Posts: 1979 Joined: Oct 2009 From the look of the seal housing holders shown in the pictures you posted, it looks like both the upper and lower housings should have a rope seal in them. When I rebuilt my V8-60 many years ago, I think one of the rope pieces was white and the other appeared to be black as though it was graphite impregnated. Before installing the rope oil seals, soak them in oil overnight so they will not be dry when installed and will conform to the shape of the holders and the crankshaft. Use a cylindrical tool that is close to or smaller than the diameter of the crankshaft and gently roll it against the the seal to force it into the holder. Cut the last seal to be installed off flush with the surface of the holder and use a little dab of silicon to seal the two pieces together. Good luck on achieving an oil tight seal. 40 Coupe 05-24-2019 @ 5:42 AM reply profile send p.m. Senior Posts: 1801 Joined: Oct 2009 There are two different pot metal seals the 78- and the 19B- they are not interchangeable. I doubt your engine uses a rope seal on the rear main. The rear seal is the labyrinth style. Without the lower pot metal seal you would be missing part of the labyrinth. and the proper oil return path to the pan. Is there a part number embossed on the rear main such as 68 , 81A??? Fordfan1 05-24-2019 @ 7:53 AM reply profile send p.m. Member Posts: 21 Joined: Mar 2012 Look up Red,s Engine talk Jan/Feb 2003 he explains the labyrinth rear seals. Early engines only had the pot metal seal in the block. I have a 1938 engine with no seal in the lower rear main cap. TomO 05-24-2019 @ 9:02 AM reply profile send p.m. Senior Posts: 7385 Joined: Oct 2009 Your crankshaft should have a thin piece of metal behind the rear main that fits into a V shaped groove in the rear pot metal seals. If you have a crankshaft without the slinger, you will have to use the pot metal pieces with squared off recess that will accommodate the rope seals. P/Ns 78-6335 & 78-6336 have the v shaped groove and are used with crank shaft P/N 68-6303-A, 91A-6303-A, 99A-6303-A and 29A-6303-A with a slinger rear seal. P/Ns 91A-6335 & 19B-6336 have the squared off groove to accommodate the rope seal and are used with the crankshaft P/N with a B-suffix and the 8BA prefix and no slinger. Either type should fit in the recess in the rear main bearing cap, the slinger may interfere with the 19B prefix lower seal. The rear main cap should also have a small pipe that directs the excess oil back into the pan. Without the correct seals, you will have a major oil leak. Tom Hoppys36 05-24-2019 @ 9:26 AM reply profile send p.m. Member Posts: 3 Joined: Dec 2018 I am new to this forum and thanks to all of you for your patience and valuable input. Fordfan1, thank you for the referral to Red’s Engine talk Jan/Feb 2003. I provided a link to that paper at the end of my post. Very interesting and brings me towards peace with installing the engine with only the top main seal. The particular rear main cap I have must not be designed to fit the lower rear main seal. After my 1937 21 stud engine is installed and running I will post and update. http://www.reds-headers.com/html/red_s_engine_talk_11.html

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