Topic: Rear main leak

joe b	-- 07-18-2011 @ 5:30 AM
	This winter I replaced the rear main oil seal on my '41 along with clutch pressure plate etc. The job now has 380 miles on it and the seal is leaking again as bad as ever. What did I do wrong?
37RAGTOPMAN	-- 07-18-2011 @ 5:38 AM
	check the oil filler filter for any clogging, to much pressure in the engine will force the oil out the rear main, its the easiest for it to escape from there, this is a remote possible, but could also be the main bearing with wear, did you plastic gauge the rear main bearing lets hear how you made out,,, 37 RAGTOPAMN
supereal	-- 07-18-2011 @ 5:52 AM
	Joe: Be sure the leak is actually from the rear crank seal. If it is leaking from inside the clutch housing, it can be from the oil pump drive cover or the pipe plug that seals the oil gallery at the rear of the block, both behind the flywheel. If you trimmed the ends of the seals at installation, it can also leak. If the leak is actually running down the back of the engine, where it is hard to see, it may be from or around the oil pressure sender. I've seen that more than once. Bar's Leaks has come out with a new oil additive claimed to seal such leaks. Usually, I don't have much faith in additives to cure mechanical problems, but Bar's is a long standing brand, it it might be worth a try before you pull the engine. This message was edited by supereal on 7-18-11 @ 5:54 AM
51f1	-- 07-18-2011 @ 7:17 AM
	Also, oil can leak between the rear main bearing cap and the block. The mating surfaces should have sealant applied. But, if you trimmed the rear seal when you installed it, that's your problem. Richard
oldford2	-- 07-18-2011 @ 4:40 PM
	I don't believe the 41 engine has an oil seal, just a slinger. If you "replaced it" You must not have a 41 engine (221). So you need to give more details. What engine do you have?? Where is the oil coming from?? Out of the "cotter pin" hole?? As Bob said, don't try to fix it with stop leak. John This message was edited by oldford2 on 7-18-11 @ 4:54 PM
supereal	-- 07-19-2011 @ 10:08 AM
	How much oil are you putting in the pan? If you don't have a filter, four quarts is the right amount. I know a lot of books say 5, but that is wrong. Five quarts in a flathead without a filter almost guarantees lots of leakage at the rear of the engine. If the engine uses a packing (rope) seal, it must have a 91A crankshaft. The slinger type is a 78 or 99A crank. The slinger type was superceded by the packing type in the 39-41 years. As engines were frequently changed as the years went by, it is difficult to know what it is without a tear down, anyway.
oldford2	-- 07-19-2011 @ 4:28 PM
	Well, this is a little frustrating and happens often. Someone posts a problem looking for help and several posts trying to help. Many times more info on the problem is requested and no response by the poster. So the helpers get turned off by no response. Why do they post??? John
supereal	-- 07-19-2011 @ 4:33 PM
	Huh?
oldford2	-- 07-19-2011 @ 4:53 PM
	Bob, My post is just asking why joeb has not responded with more details. John
supereal	-- 07-19-2011 @ 9:29 PM
	Thanks, John. Now I understand. For those of us who try to help, getting at least the year and model is a "must". While old Fords probably look alike to many, the differences, as you know, are often subtle, and it certainly helps all of us to focus on suggesting an answer.
joe b	-- 07-20-2011 @ 5:48 AM
	Sorry all about the lack of a response to my asking for help. A few problems with an old body (mine, not the Ford). The oil filler screen is nice and clean. I replaced the main bearings and had the crank ground. Did use plastgauge on the bearings. Engine takes 4 Qt. of oil. It does look like the oil is coming from the cotter pin hole. I am going to try to get into it probably next week. Be patient,I will let you know. Thanks for all the advice.
joe b	-- 07-26-2011 @ 12:22 PM
	Well I finally got under the car. It looks like it is not a rear main leak but is coming from the transmission shift shafts where they go into the trans. I put 80-90wt.in it. Maybe I should go to 600 wt. Thanks to all who replied.
supereal	-- 07-26-2011 @ 8:22 PM
	Don't use 600W. It is just thin asphalt, and was used in the Model A days. If you don't want to pull and fix the problem, you might try the new Barr's Leaks sealer. If you want a thicker oil, get 140W.
joe b	-- 07-27-2011 @ 7:59 AM
	Super, I would like to wait until winter for the repair due to shows and summer driving here in Ohio. I think I will try 140 wt. until then. Do you think this will be OK if I check oil level now and then? Also, what is the Bar's leak brand or product name. Thanks
supereal	-- 07-27-2011 @ 12:39 PM
	The Barr's product is new. It is intended to seal gasket seepage. Any place that sells Barr's should have it. You can reduce leakage by filling the transmission only to the point you can reach the oil by crooking a finger thru the filler hole. We used to have lots of leakage around the shaft holes in the Model A transmissions. Finally, we made a cover for that area,put a gasket under it, and fastened it with a threaded hole in the case. One of the problems with most, if not all, old Fords is that they leak in so many places. I suspect that the normal oil coating on the underside of the cars may be a reason they have lasted so long. In the colder climates, many used to spray the underside of their vehicles with used motor oil to rustproof them from winter snow and slush.
joe b	-- 08-02-2011 @ 1:22 PM
	Just to update, I changed out the oil and used 140 wt. plus Rislone stop leak. I went on a trip and put about 3oo miles on the car and there is a vast improvement. The leak has not completely stopped but now I leave a drop instead of a silver dollar size drip when it sits over night. Should hold until I can get to it this winter. Thanks all.

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