Need advice on Shortblock...

MustangDanny · 01-14-2002, 11:40 AM

I have a oil leak on my shortblock. I'm pretty sure that it is coming from the rear bearing. About 6 months ago I put a new rear main seal in when I put a new tranny and clutch in. I am 99.9% sure that I put in in correctly. But I think that oil is still leaking from that area. Is it possible that the bearing (pilot bearing?) is leaking? Or is it more likely that the oil pan gasket is leaking? A couple weeks ago I degreased the whole area and put the car on a lift and ran it for a while at different rpms to try to see where the leak would come from. I noticed it start to leak from inside the clutch area, behing that plate that covers the flywheel.

So here's my dilema. Do I rebuild the shortblock (or maybe a new one if my income tax check is nice enough), or do I just have that bearing and seal replaced? Has anyone ever done this or had it done? How much did it run you or how hard was it for you to do? If I don't have to rebuild the shortblock now (and can wait for next year to do that) then I can spend money on chassis, suspension and maybe even heads and cam.

Rick 91GT · 01-14-2002, 01:22 PM

Most likely it is the rear seal, the pilot bearing is inside the end of the crank shaft and would not leak.

To swap it out you need to pull the exhaust, drive shaft and transmission and bell housing, then pull the clutch, flywheel and backing plate. Then you will be able to see the rear main seal and the pilot bearing.

To replace the seal use a small flat head screw driver to pry it out or use a sheet metal or dry wall screw to tap into the seal and then pull it out. The Pilot bearing is easily removed with a bearing removal tool which you can rent from most auto parts stores or..you can place small pieces of soaked paper towl inside the bearing and use a piece of roll stock or a punch just big enough to go in the bearing and hit it with a hammer.

This will pack the water and paper towel behind the bearing and puch it out, you can use a heavy grease as well..but like I said a bearing removal tool is much easier.

Clean the crank off with a parts cleaner and make sure that area is dry, then put a small coat of Permatex on the outside of the new rear seal (FEL-PRO TEFLON REAR SEAL WORKS BEST $15)put a small amount of oil on the crank so that the seal doesn't rip when you are tapping it in place, I use a small flat punch and a hammer to tap the seal into place.

Then put it all back together!

MustangDanny · 01-14-2002, 01:51 PM

So you are saying the only thing that can be leaking back there is the rear main seal? Like I said though... I changed the rear main when I put the new clutch and tranny in. And I did it just like you descripbed. It went in perfectly. But something is still leaking back there, and it leaks on my clutch which is causing it to slip. I wouldn't bother with it and just live with it if it wasn't hurting my performance, but it sucks because it's killing my clutch.

avbcon12 · 01-14-2002, 02:10 PM

ok, work with me here on this analogy:

i once was rebuilding a 4.0l V-6 from a ranger. i pulled the tranny because i needed to do the rear main (it was leaking). after i got everything back together and fired it up, drove it around, crawled under to look at it. it was leakning more than before. i know for a fact that i did it correclty.
that got me talking to a bunch of people. one of the guys said that because the motor had so many miles (175,000), that because the seal is leaking more it could be that my crank is warped. and its leaking more because the old seal was all soft and plyable so it conformed to the crank as it moved.
so i pulled the motor, pulled the crank, and had it balanced. it was WAY out of balance. i got a new crank and put everything back together and it all worked out great!

now im not saying that this is your problem too but i saw you had a lot of miles on your motor and im sure you dont always granny it so......

take it how you will,,,

Adam

Rick 91GT · 01-14-2002, 02:27 PM

Usually when oil is in the bell housing it is from the rear seal although it could be from the oil pan also, it is hard to pin point if the rear of the pan is leaking under hard acceleration.

If the oil gets to the clutch it will kill it, as stated above if the crank is harribly out of balance or scored/grooved it will cause the seal to leak although if it was that out of balance you should have vibrations in the motor.I have seen guys have brand new seals leak because they were ripped on the install or they do not seat correctly, that is very easy to do.

If it is the oil pan it is easiest to change with the motor out of the car or some guys just prop it up so they have enough clearance to drop the pan. If it is get the THICK re-enforced Fel-Pro i will either be grey or blue, these work the best.

MustangDanny · 01-14-2002, 02:27 PM

That's actually what I was looking to hear avbcon12. I wasn't sure if it was possible that it could be leaking as a result of something else being worn/broken. That's why I mentioned/asked if it could be the pilot bearing. I think that the safe route is to stick with my plan than and to put together a new shortblock.

MustangDanny · 01-14-2002, 02:30 PM

Hmmm, I have been noticing some vibrations from the drivetrain. I recently put a new FMS aluminum driveshaft and that helped a bit, but there are still some vibrations. Could this be the engine out of balance?

GCMustang · 01-14-2002, 02:57 PM

This sounds plausible. An imbalanced crank, or a scored bearing. Could have gotten some foreign particles into the pan and made its way into a bearing.

Disassemble the block when you get it out, and let us know!

avbcon12 · 01-14-2002, 05:29 PM

MUSTANGDANNY:

I wouldnt want to be the one that tells you to build a new shortblock. but i do know that if you did it would solve all of your problems. i just know that it can happen, and is deffinatly a possibility with your miles.

hope i helped,
Adam

01-14-2002, 11:40 AM	#1
MustangDanny Registered Member Join Date: Nov 2001 Location: Dover, DE Posts: 70	Need advice on Shortblock... I have a oil leak on my shortblock. I'm pretty sure that it is coming from the rear bearing. About 6 months ago I put a new rear main seal in when I put a new tranny and clutch in. I am 99.9% sure that I put in in correctly. But I think that oil is still leaking from that area. Is it possible that the bearing (pilot bearing?) is leaking? Or is it more likely that the oil pan gasket is leaking? A couple weeks ago I degreased the whole area and put the car on a lift and ran it for a while at different rpms to try to see where the leak would come from. I noticed it start to leak from inside the clutch area, behing that plate that covers the flywheel. So here's my dilema. Do I rebuild the shortblock (or maybe a new one if my income tax check is nice enough), or do I just have that bearing and seal replaced? Has anyone ever done this or had it done? How much did it run you or how hard was it for you to do? If I don't have to rebuild the shortblock now (and can wait for next year to do that) then I can spend money on chassis, suspension and maybe even heads and cam. __________________ -- -1991 LX 5.0 Sedan, 5 spd (new 'Z' tranny), 3.73, aluminum DS, Hedman headers, 190 LPH, MAC CAI, Flowmaster catback. (170K miles on motor) Best ET: 14.434 @ 96.04 MPH - 2.205 60' (Radials) My Notch

01-14-2002, 01:22 PM	#2
Rick 91GT Procharged! Join Date: May 1999 Location: Hanover, PA Posts: 1,539	Most likely it is the rear seal, the pilot bearing is inside the end of the crank shaft and would not leak. To swap it out you need to pull the exhaust, drive shaft and transmission and bell housing, then pull the clutch, flywheel and backing plate. Then you will be able to see the rear main seal and the pilot bearing. To replace the seal use a small flat head screw driver to pry it out or use a sheet metal or dry wall screw to tap into the seal and then pull it out. The Pilot bearing is easily removed with a bearing removal tool which you can rent from most auto parts stores or..you can place small pieces of soaked paper towl inside the bearing and use a piece of roll stock or a punch just big enough to go in the bearing and hit it with a hammer. This will pack the water and paper towel behind the bearing and puch it out, you can use a heavy grease as well..but like I said a bearing removal tool is much easier. Clean the crank off with a parts cleaner and make sure that area is dry, then put a small coat of Permatex on the outside of the new rear seal (FEL-PRO TEFLON REAR SEAL WORKS BEST $15)put a small amount of oil on the crank so that the seal doesn't rip when you are tapping it in place, I use a small flat punch and a hammer to tap the seal into place. Then put it all back together! __________________ *D/R 10108 NMRA Drag Radial, 25.5 chassis, F1R* *Check out RNH Performance Performance Engines and Custom Fabrication.* *From Mild to Wild we can build what you want, when you want it.* FOR SALE Stainless Steel Torque Box Supports

01-14-2002, 01:51 PM	#3
MustangDanny Registered Member Join Date: Nov 2001 Location: Dover, DE Posts: 70	So you are saying the only thing that can be leaking back there is the rear main seal? Like I said though... I changed the rear main when I put the new clutch and tranny in. And I did it just like you descripbed. It went in perfectly. But something is still leaking back there, and it leaks on my clutch which is causing it to slip. I wouldn't bother with it and just live with it if it wasn't hurting my performance, but it sucks because it's killing my clutch. __________________ -- -1991 LX 5.0 Sedan, 5 spd (new 'Z' tranny), 3.73, aluminum DS, Hedman headers, 190 LPH, MAC CAI, Flowmaster catback. (170K miles on motor) Best ET: 14.434 @ 96.04 MPH - 2.205 60' (Radials) My Notch

01-14-2002, 02:10 PM	#4
avbcon12 Registered Member Join Date: Jul 2001 Location: West Bloomfield, MI Posts: 391	ok, work with me here on this analogy: i once was rebuilding a 4.0l V-6 from a ranger. i pulled the tranny because i needed to do the rear main (it was leaking). after i got everything back together and fired it up, drove it around, crawled under to look at it. it was leakning more than before. i know for a fact that i did it correclty. that got me talking to a bunch of people. one of the guys said that because the motor had so many miles (175,000), that because the seal is leaking more it could be that my crank is warped. and its leaking more because the old seal was all soft and plyable so it conformed to the crank as it moved. so i pulled the motor, pulled the crank, and had it balanced. it was WAY out of balance. i got a new crank and put everything back together and it all worked out great! now im not saying that this is your problem too but i saw you had a lot of miles on your motor and im sure you dont always granny it so...... take it how you will,,, Adam __________________ 90 GT black/ grey leather ported GT-40 heads w/ 1.7RR, Cobra intake w/ ported lower, 24# injectors, 190LPH pump, 75mm Pro-M MAF, 65mm TB, K&N panel, BBK long tubes, Off road H-pipe, 2 ch. Flowmaster, Black magic fan, Kirban FPR, 180 deg. T-stat, 3.73's, Steeda Tri-Ax, 130 amp alt. Accell 8.8 race wires/cap/rotor, motorcraft plugs, Factory Five suspension, etc etc etc.... http://avbcon12.stangnet.com

01-14-2002, 02:27 PM	#5
Rick 91GT Procharged! Join Date: May 1999 Location: Hanover, PA Posts: 1,539	Usually when oil is in the bell housing it is from the rear seal although it could be from the oil pan also, it is hard to pin point if the rear of the pan is leaking under hard acceleration. If the oil gets to the clutch it will kill it, as stated above if the crank is harribly out of balance or scored/grooved it will cause the seal to leak although if it was that out of balance you should have vibrations in the motor.I have seen guys have brand new seals leak because they were ripped on the install or they do not seat correctly, that is very easy to do. If it is the oil pan it is easiest to change with the motor out of the car or some guys just prop it up so they have enough clearance to drop the pan. If it is get the THICK re-enforced Fel-Pro i will either be grey or blue, these work the best. __________________ *D/R 10108 NMRA Drag Radial, 25.5 chassis, F1R* *Check out RNH Performance Performance Engines and Custom Fabrication.* *From Mild to Wild we can build what you want, when you want it.* FOR SALE Stainless Steel Torque Box Supports

01-14-2002, 02:30 PM	#7
MustangDanny Registered Member Join Date: Nov 2001 Location: Dover, DE Posts: 70	Hmmm, I have been noticing some vibrations from the drivetrain. I recently put a new FMS aluminum driveshaft and that helped a bit, but there are still some vibrations. Could this be the engine out of balance? __________________ -- -1991 LX 5.0 Sedan, 5 spd (new 'Z' tranny), 3.73, aluminum DS, Hedman headers, 190 LPH, MAC CAI, Flowmaster catback. (170K miles on motor) Best ET: 14.434 @ 96.04 MPH - 2.205 60' (Radials) My Notch

01-14-2002, 02:57 PM	#8
GCMustang Registered Member Join Date: Jan 2002 Location: Gulfport, mS Posts: 18	This sounds plausible. An imbalanced crank, or a scored bearing. Could have gotten some foreign particles into the pan and made its way into a bearing. Disassemble the block when you get it out, and let us know! __________________ -SamP, BSME- ~1998 Mustang GT~ - Saleen Body Kit, Cobra R wheels (17x10.5 w/ 315/35 in rear and 17x8 w/ 245/45 out front), 3.27 gears, FMS C Springs. . . Waiting for income tax check to do 99PI headswap! RateMyStang

01-14-2002, 05:29 PM	#9
avbcon12 Registered Member Join Date: Jul 2001 Location: West Bloomfield, MI Posts: 391	MUSTANGDANNY: I wouldnt want to be the one that tells you to build a new shortblock. but i do know that if you did it would solve all of your problems. i just know that it can happen, and is deffinatly a possibility with your miles. hope i helped, Adam __________________ 90 GT black/ grey leather ported GT-40 heads w/ 1.7RR, Cobra intake w/ ported lower, 24# injectors, 190LPH pump, 75mm Pro-M MAF, 65mm TB, K&N panel, BBK long tubes, Off road H-pipe, 2 ch. Flowmaster, Black magic fan, Kirban FPR, 180 deg. T-stat, 3.73's, Steeda Tri-Ax, 130 amp alt. Accell 8.8 race wires/cap/rotor, motorcraft plugs, Factory Five suspension, etc etc etc.... http://avbcon12.stangnet.com

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
eibach advice needed	mustardjohn	Small Ponies	6	08-19-2012 08:12 PM
Advice on injectors...PKRWUD I'd like your advice on this one as well	silver_pilate	Windsor Power	3	06-09-2003 08:59 AM
building a stroker need advice on solid roller or hydrallic roller cam ??	Mustangboy89	Windsor Power	4	06-06-2003 02:10 PM
question & advice...please	Robocop	Windsor Power	7	05-24-2003 03:47 AM