NAA rear seal again-long

fixerupper

Well-known Member
Still working on this NAA trying to get the rear seal to not leak. When we got the tractor with the pan was barely bolted on and the rear bearing cap was in a box. The previous owner had tried five times to get the rear seal to quit leaking without splitting the tractor so we split it and put the engine on the stand where we could work on it. One major culprit we found wasn't even the engine, it was the transmission input seal on the two speed that he had added. The bellhousing was full of oil and that tranny seal was the culprit. We replaced that seal and it's sealing OK.

We put in a new Felpro neoprene rear engine seal along with the neoprene side seals with the wires you drive in along side, put it together, ran it up and down the road and the rear engine seal still leaks, the seal itself, not the side seals.

I have been reading the archives here on YT and found lots of very good information on installation. I have followed all of the helpful suggestions, but this thing still leaks. In one of the posts in the archives Felpro seal #BS6143-3 was mentioned. The felpro seal I have has 61411 on the seal itself. I tried Googling the numbers but came up empty handed. Is the #BS6143-3 a kit, or is it the part number for the seal itself? Also, Hobo, you mentioned using compressed air and bubble soap to check the seal while the engine is still on the stand. How do you do that? This time I want to be sure it doesn't leak before it comes off the stand.

On another website I was reading up on tips to successful two piece seal replacement in car engines and crankshaft misalignment in the seal due to align boring the block came up. I highly doubt this is the case with this engine since the original seal just dripped a bit before the owner tackled this job. Jim
 
Call in Hobo on this one. he's made plenty of posts on rear mains.

I personally will live with a very occasional drip from a rear main.. these fords seem to like a leaky rear main... :) i realize some won't want the drip. concrete driveway..e tc.. etc.
 
This thing is slinging oil in just fifteen minutes of running. If I can get it down to a drip I'll call it good enough. I've read Hobo's posts in the archives and he's the true go-to man for this problem. In one of his posts he had mentioned using compressed air and bubble soap to test the seal while it is still on the stand, but I don't know how he did it. I have several ideas on how to test it while on the stand but I don't know if they will work. I'll just have to wait and see. Jim
 
Does the crank have what looks like light knurling where the seal goes? If that is the case it works with a rope seal but not to good with neoprene style.
 

I replaced a rear main on a 172 with the two piece neoprene two years ago. It has not leaked significantly. Before putting the oil pan on I took it off the stand and set it upside down on the floor. I supported it at an angle so that I could put some oil against the seal and just let it sit to see if it would leak. I didn't look at it as being definitive but it sure made me feel better and ready to go ahead and finish it up.
 
OK, I have some new news. He had put new rod and crank bearings in it when he had the pan off to replace the subject seal. Crank is stamped .010 for both rods and mains and the bearing shells are stamped STD. I called him and he still had the old bearing shells so he looked at them and they were vaguely stamped .010 in barely readable ink. I don't have any Plastigage so I put a dial indicator on the crank with the main bearings torqued down and I got .012 up and down play in the crank. No need to explain any more about it. The owner is an old retired career Deere mechanic who has some age on him so when I called him to tell him about the bearings he admitted to having a red face. Jim
 
The knurling of the crank shaft came with the first neoprene two peace seal, from Ford. I would suspect a knurled shaft and a rope seal would not be the best combination
 
Wow.....12 thousanths of "up-and-down" play in the crankshaft. I'm surprised that it had any sort of oil pressure at all. :shock:

Sounds like you're making progress now!
 
(quoted from post at 16:32:24 04/05/14) OK, I have some new news. He had put new rod and crank bearings in it when he had the pan off to replace the subject seal. Crank is stamped .010 for both rods and mains and the bearing shells are stamped STD. I called him and he still had the old bearing shells so he looked at them and they were vaguely stamped .010 in barely readable ink. I don't have any Plastigage so I put a dial indicator on the crank with the main bearings torqued down and I got .012 up and down play in the crank. No need to explain any more about it. The owner is an old retired career Deere mechanic who has some age on him so when I called him to tell him about the bearings he admitted to having a red face. Jim

Yes, you have to buy plenty of plasitgauge. I about went nuts determining what was what with my 9000 when I put new bearings in it. I think that it had blues on the mains and .020 on the rods.
 
That must be the opsite for car engines. It is not a cross hatch knurl only in one direction. It is slanted so that it pushes the oil back to the pan. It works fine for rope but wears the lip on neoprene seals.
 

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