Rear main seal leaking
05-01-2010, 02:39 PM
#1
Drifting
Thread Starter
Rear main seal leaking
Hi all,
Well, after 21 long dry years, it looks like my rear main seal is starting to leak--not bad, but if I let the car run for a few minutes in my driveway, there is always a spot.
When I first got the car back in 1974, the original 390HP 427 was gone and it had an old tired 1963 327/250 in it. The rear main in that one leaked, so I pulled the pan and as I remember, I was able to spin out the top half of the seal with very little trouble. That engine was only 11 years old when I did that---Now however, this engine (427/435) is 21 years old, having been rebuilt and assembled by me in 1989.
How many of you have been able to pull the rear main seal out of a 21 year old engine without going through a major dissassembly (pulling the crank) ???
Well, after 21 long dry years, it looks like my rear main seal is starting to leak--not bad, but if I let the car run for a few minutes in my driveway, there is always a spot.
When I first got the car back in 1974, the original 390HP 427 was gone and it had an old tired 1963 327/250 in it. The rear main in that one leaked, so I pulled the pan and as I remember, I was able to spin out the top half of the seal with very little trouble. That engine was only 11 years old when I did that---Now however, this engine (427/435) is 21 years old, having been rebuilt and assembled by me in 1989.
How many of you have been able to pull the rear main seal out of a 21 year old engine without going through a major dissassembly (pulling the crank) ???
RON
05-01-2010, 02:52 PM
#2
Le Mans Master
use a small brass drift to push one side of the upper seal and grab the other side with a pair of needle nose pliers....lube up the new one and push it into place....nuttin to it....good luck
05-01-2010, 04:57 PM
#3
Race Director
It shouldn't be a problem. My motor had about 15 years on the build when I changed the rear main seal. It's not a huge job as the pan can be pulled by dropping the steering linkage on one side. There is some strange procedure for setting the crank thrust clearance but other than that it's pretty straightforward.
Dan
Dan
05-01-2010, 06:09 PM
#5
Race Director
Member Since: Jan 2002
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C2 of the Year Finalist - Modified 2020
With the pan off, check the side rails for any bolt hole dimpling. True them up with a brass drift and a ball pein hammer. When you install the pan, use the actual torque spec for tightening. I know, it sound corny, but it works. 
Dennis
Dennis
05-01-2010, 08:27 PM
#6
Le Mans Master
Member Since: Mar 2005
Location: Rocklin California
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All good suggestions but if it's a minor leak, leave well enough alone. Drive it, and have fun because if you fix it, it may leak again and really upset you. Not worth it unless it is a bad leak. 
05-01-2010, 08:43 PM
#7
Safety Car
05-01-2010, 09:51 PM
#8
Melting Slicks
my OCD kicked in and my drip had to be fixed. PIA make sure you get a gooooood new one...hi perf..double wiper....I think they are blue as I recall felpro? get a new one piece oil pan gasket too...you know the drill..clean clean clean off the old gasket and goo...install the new one and do not over tighten the bolts...good luck
05-01-2010, 10:16 PM
#9
Pro
Fel pro makes an offset Look it up and just get one- rides on a clean area of the crank.... a must have as they seem to wear a groove that leaves a standard seal with too much clearance- had the problem myself on a 59,000 mile original small block- Hate doin' it twice!
05-02-2010, 09:00 AM
#10
Burning Brakes
While you have the pan off throw in a new set of main bearings. As the bearings wear the crank can float around and has more clearance for oil to leak around the seal. I worked on big Cat engines for years and sometimes just changing the bearings cured a rear main leak. JMO> Dave
