questions on a 352 rear main seal

unclejtl · Post by **unclejtl** » October 26, 2010, 9:35 am

hello, well I just pulled my engine and trans (np 4-speed) to replace the slipping clutch, fix the blown out intake seal (rear) and replace leaki exhaust manifold gaskets. what i found was there was a fair amount of oil in the bell housing area and the disc looked "wet-ish". the whole back of the engine and trans was covered in oil and grime (been putting this off since i bought it). now I have read alot of places that these rear main seals dont leak that much... well i don't want to pull this again, so what's involved in replacing the rear seal? i assume it's a rope seal. is it doable without pulling the crank? anybody done this before?

thanks for any advice.

Uncle Skip · Post by **Uncle Skip** » October 26, 2010, 10:11 am

unclejtl
Welcome to the family. The FE rear main seal is a biatch to replace properly. Maybe someone like Hawkrod or winr can give you more specific instructions, but the critical point is the two "square" legs that go on the outside of the rear main bearing, and the two little pins that slip in to the slot to expand the seal.
I use a very thing sealant that is used on outboard motors called Marpox 1000 to stop the leaks. Just be careful, take your time and do it like the instructions say.
I tried silicone but didn't have very good luck with that.
Hope this helps.
U@ss

unclejtl · Post by **unclejtl** » October 26, 2010, 11:14 am

thanks, so it can be done without pulling the crank? just the cap?

Uncle Skip · Post by **Uncle Skip** » October 26, 2010, 1:06 pm

Jason.
The seal I'm talking about is the seal on the main cap to the block. If you're talking about the crankshaft seal, no. You'll have to take the rear main off, loosen all the main bearings, take the crankshaft snout spacer out of the motor and pry up the back of the crank shaft and block it, then gently slide the top half of the seal out Not easy, but I has been done. I'll defer to Hawkrod on the exact method, but I have done it this way in the past.
Personally, I'd pull it down while you have the motor out and examine all the bearings and other seals, especially the aforementioned front timing cover seal.
Include inspecting of the oil pump, and get a HD oil pump shaft when you do.
Good luck. Better to do it now than have to pull it back out because something else lets go later.
U@ss

unclejtl · Post by **unclejtl** » October 26, 2010, 1:41 pm

was just doin a search and came up with this. is this what you mean?

http://www.squarebirds.org/rear_main_seal.htm

Uncle Skip · Post by **Uncle Skip** » October 26, 2010, 3:10 pm

Yep. Thas it.
I use a brass punch to drive in the steel pins, but take your time with that.
Hold them in place when you drive them in with the little needle nosed ViceGrips I talked about earlier.
You can see the half seals I was talking about too. If the crank is elevated off the saddle, they can be coaxed out and replaced (engine on bench, not in the car).
I use the Marpox when I join those two also.
Hoping some of the other guys chime in. My way is not the only way.
Skipper

DukeRoche · Post by **DukeRoche** » October 26, 2010, 3:28 pm

Jason,

Did you take your avatar pic from my refridgerator?

unclejtl · Post by **unclejtl** » October 26, 2010, 3:51 pm

thanks uncle skip.

dukeroche, yep last saturday night when you were dancin on the table

DV65CustomCab · Post by **DV65CustomCab** » October 27, 2010, 6:32 am

I had the oil clutch and giant mess too, and am 90% sure it was just the intake causing all the mess. I didn't touch the rear main on mine, far too much work when most folks tell me that's not the problem. So far it's remained pretty dry under there.

Hawkrod · Post by **Hawkrod** » October 27, 2010, 8:02 am

Yes, it is doable but it is not fun as that article notes. The sad part of the article is he did not do the top half and he was already there. It takes no more effort at that point. You don't need to drop the crank and the only main cap you mess with is the last one but it is a truly ugly job and it is rarely actually the problem. As noted, most leaks atributed to the rear main seal end up being something else like the rear of the intake or valve covers or a rear oil galley plug. Hawkrod

banjopicker66 · Post by **banjopicker66** » October 27, 2010, 8:24 am

I have had 4 high mileage FEs, 2 352s, a 360 and a 390. All of them leaked badly at one time or another, but none - repeat none of them leaked at the rear main crankshaft seal.
All of them leaked at the rear intake gasket - that is, until I fixed it right.
The keys to fixing that pesky rear intake gasket:
1. Set the front and rear gaskets in place, on top of a thin layer of RTV sealant.
2. Let cure overnight.
3. Put on a medium layer of RTV oon top of the gaskets when re-installing the intake
4. Put an additional blob of RTV in the corners
5. Set the intake down straight; a cherry picker is best of the engine is still int the truck.

I didn't have a single one leak after that.

unclejtl · Post by **unclejtl** » October 27, 2010, 9:03 am

thanks guys for the info. i'll look closer at it to figure how that much oil coulda made it into the bellhousing.

DV65CustomCab wrote:I had the oil clutch and giant mess too, and am 90% sure it was just the intake causing all the mess. I didn't touch the rear main on mine, far too much work when most folks tell me that's not the problem. So far it's remained pretty dry under there.

how long has it been? we tow a 18" 1964 traveleze trailer and i don't want to get stuck in the desert with another slippy clutch.

DukeRoche · Post by **DukeRoche** » October 27, 2010, 2:43 pm

Your welcome for the advice Jason, and next time take pictures. Its rare that I dance