Rear Main Oil Leak

IMLost · #1 (**permalink**) 06-12-2010, 10:08 AM

I have an old model #178 that I had to rebuild the engin. I have a rear main leak. You guys with experiance may be able to help me. Will I be able to drop the transmission to get to it or will it all have to come out?
Thanks

Snakebit · #2 (**permalink**) 06-12-2010, 10:38 AM

What size motor???

IMLost · #3 (**permalink**) 06-12-2010, 10:43 AM

302 that i just stroked

Snakebit · #4 (**permalink**) 06-12-2010, 11:05 AM

I had to replace the rear main in my 302. It had a 2 piece seal. You need to drop the pan, and remove the rear main cap. If its a later block with a 1 piece seal, You need to pull the trans, clutch, and flywheel to change the rear seal. Make sure you replace it with a FelPro Performance rear seal. The seal I replaced was the rubber one supplied with the gasket set, POS. The Felpro seal is dry as a bone. Not hard to do, just very time consuming.

IMLost · #5 (**permalink**) 06-12-2010, 11:45 AM

It's a newer block with a one piece seal. Yes; I used the one in the gasket set. I took the engin and transmission out in one piece and thus reinstalled as one also. I just know how tight the space is there and was hoping that I did not have to pull the engin out to fix it.
I'm trying not to have to do all of that work all over again. I am hopeing that someone with an older car like mine can tell me if they have pulled the tranny out by itself by sliding back far enough to clear the transmission shaft.
All help is good in this learning process.

Jac Mac · #6 (**permalink**) 06-12-2010, 02:53 PM

Did you apply sealant to the flywheel/crankshaft bolt threads, might not be the seal leaking.

IMLost · #7 (**permalink**) 06-12-2010, 06:11 PM

I believe so. Really took our time so this kind of stuff would not happen. didn't want to do it once for practice then for good. I know i've got to tear it down I am just trying to figure out if I can chase it in the car without removing he engin again.
Thanks mate.

Hitch · #8 (**permalink**) 06-13-2010, 08:07 PM

Not sure how you can get the tranny to slide back. Hell I had to replace the drive shaft and there is no way to get it out with the tranny in place. I ended up having an extra take apart yoke from my Vette that I got with the Tremec. I had to use it when I replace the driveshaft. Then with the one piece rear main there is no way that I know of that you can replace that in the car. I feel you about having to R&R the motor, I picked up #86 this year and the motor just expired the other day. #1 Piston gave up the ghost and with a SVO block that had been maxed bored to .030 over I'm building a new motor.. Yea....

Dave

PoppyMod · #9 (**permalink**) 06-14-2010, 05:48 AM

Quote:

Originally Posted by IMLost

302 that i just stroked

How new is the engine? How bad is the drip.seepage?
Are you running any kind of PCV system? FYI, relieving any block pressure through a PCV system or better yet an evac system will greatly reduce any tendencies for seepage.
I had a similar issuie after taking great care in the setting the rear seal, and still had a small leak. However, after a few hundred miles and running a closed PCV system the leak went away.
It depends on how sever the leak.
Goos Luck!

blykins · #10 (**permalink**) 06-14-2010, 06:10 AM

It's hard to screw up a one piece seal install. I would check to see that it's not coming from another location first.

lovehamr · #11 (**permalink**) 06-14-2010, 06:33 AM

Quote:

Originally Posted by Jac Mac

Did you apply sealant to the flywheel/crankshaft bolt threads, might not be the seal leaking.

If those bolts are exposed to oil then his seal is most definately leaking. Should be no oil on the front or back of those bolts.

blykins · #12 (**permalink**) 06-14-2010, 06:45 AM

The flywheel bolt hole is a thru hole on the later model stuff. It goes all the way through the crank flange and could leak oil if sealant is not put on the bolts.

DAVID GAGNARD · #13 (**permalink**) 06-14-2010, 08:54 AM

Quote:

Originally Posted by blykins

The flywheel bolt hole is a thru hole on the later model stuff. It goes all the way through the crank flange and could leak oil if sealant is not put on the bolts.

yep, and he says it's a 302 based stroker motor, all the stroker cranks I've seen have the holes going thru the rear crank flange.....

David

lovehamr · #14 (**permalink**) 06-14-2010, 10:40 AM

Well, yeah, you're right, if those holes go all the way through to the oil they need to be sealed.....

IMLost · #15 (**permalink**) 06-14-2010, 04:28 PM

Well guys you have confirmed what unfortunately I thought I knew. It's a 2 piece seal tjat is prone to leak. From what i have found out more than likely it's time for tools. All I can hope for is the crank was knurled and for the life of me I don't remember. I'll know Thursday when it 's take it apart time. Thanke to everyone for the feedback.

DAVID GAGNARD · #16 (**permalink**) 06-14-2010, 05:20 PM

Quote:

Originally Posted by IMLost

Well guys you have confirmed what unfortunately I thought I knew. It's a 2 piece seal tjat is prone to leak. From what i have found out more than likely it's time for tools. All I can hope for is the crank was knurled and for the life of me I don't remember. I'll know Thursday when it 's take it apart time. Thanke to everyone for the feedback.

Actually I've had better luck with the old type 2-piece seals than the newer one piece as far as leaks go!!!!!!!!!!!!!!!

Clean out the area extremely well where the seal will go into, add a very,very light coat of RTV to the outside of the seal and install in it's place, before putting the rear main cap on, add a small dab of RTV to each end of the seal, and torque down, also put some motor oil on your finger and oil the inner side of the seal where it will contact the crank, not much, you don't want to install it dry.......

Can't remember the last time I had one leak, I built the 351-W in my 65 Mustang in the mid 90's, it's been used and abused, a LOT and so far has not leaked one drop of oil and I've seen oil temp numbers at 250 degrees on some road courses!!!!!!!!

David

Excaliber · #17 (**permalink**) 06-14-2010, 05:27 PM

Whew, thank goodness this thread isn't about an FE main seal leak, we already got the intense discussion going on else where.

IMLost · #18 (**permalink**) 06-14-2010, 07:26 PM

I agree sir. That is why i don't get imvolved to much. No one is always right and we all have a different view of this "hobby". I believe if anthing I tried to hard to keep it from leaking in the first place; maybe to much rtv which is keeping the seal from functioning properly. I just didn't want to have to pull the whole thing out again. I've talked to a dozen people. Most say "damn 2 piece seals" and others say no problem if it is done right. Get the opinion and then do it. Right for some,wrong for others.
Thanks.

Jac Mac · #19 (**permalink**) 06-14-2010, 11:23 PM

Two Piece Seal,
Check that the pin has been removed from the seal groove in the cap & fill the hole with silicon or a bit of alloy rod, make sure that it does not interfere with the lower seal half in the groove.

Apply a bit of grease to the crank seal surface, make sure you have the seal facing the correct direction then slide the top half of the seal into place around the crankshaft taking care to prevent the OD of the seal from getting cut on the sharp edge of the block/cap face until the seal is in a position of about 1/2" up at one end & 1/2" down at the other, now sit the lower half seal in place in the block where the end is approx 1/2" up, this ensures the seal ends will be correctly matched, now apply a very small amount of 'Right Stuff' to the cap mating surface just around the seal groove area & carefully refit the cap ( with rear main brg shell fitted

) & retorque.

Sledge · #20 (**permalink**) 06-16-2010, 09:38 AM

I have BDR #168. I was able to remove just the trans from the car (twice!) only by cutting the cross-brace for the seat belts(?) a little wider than the trans tunnel (I have a built-up T-5). Then I was able to get the driveshaft up and out of the way, and BARELY had room to jockey the trans aft and down, but I got it out.

I fabbed some angle iron to replace the cut brace, bolted it in, and it seems to be working just fine.

Cheers