Rear main seal leaking
Thread Starter
TECH Enthusiast
iTrader: (22)
Joined: Aug 2004
Posts: 544
Likes: 0
From: >>>_FRISCO_MUSCLE_<<<
Rear main seal leaking My rear main seal was leaking motor oil like crazy. I think it's just the rear main seal worn out. So I have the clutch and rear main seal replaced. After all that, the rear main seal STILL leaking oil like crazy. My installer said it could be excessive pressure created at the crank case area.
It's a 02 Formula with 108k miles on it. I've headers, exhaust, FAST 90/90, SLP lid and that's it. IIRC, this problem starts after I installed the FAST 90/90. However, the engine didn't have any running issues, ie vaccum leak. It still runs strong every gear.
My question is, what and where should I check on it? PVC valve or worn piston ring? Do I've to take out the tranny and redo the rear main seal AGAIN? I've a track day on next Friday so I've get it fix ASAP.
It's a 02 Formula with 108k miles on it. I've headers, exhaust, FAST 90/90, SLP lid and that's it. IIRC, this problem starts after I installed the FAST 90/90. However, the engine didn't have any running issues, ie vaccum leak. It still runs strong every gear.
My question is, what and where should I check on it? PVC valve or worn piston ring? Do I've to take out the tranny and redo the rear main seal AGAIN? I've a track day on next Friday so I've get it fix ASAP.
Last edited by darknessxyz; May 27, 2010 at 04:31 AM.
It's remotely possible that crankcase pressures could be an issue, but highly unlikely. I'm not trying to discount your installer, but it's very possible he didn't install the seal right. Those are tricky to get in. I've seen several people over the years not replace them correctly, and I've even done it myself a couple of times way back in the day. It took a while to get the hang of it.
As for crank case pressures, if you are having an issue with that then put a Metco breather on the car. It will help release the pressure, and give your piston rings a break too. I recommend this mod on an LS engine.
As for crank case pressures, if you are having an issue with that then put a Metco breather on the car. It will help release the pressure, and give your piston rings a break too. I recommend this mod on an LS engine.
Thread Starter
TECH Enthusiast
iTrader: (22)
Joined: Aug 2004
Posts: 544
Likes: 0
From: >>>_FRISCO_MUSCLE_<<<
Thanx for reply. I've some feeling he either didn't replace it or put it in wrong. However, he's specialize in LS engine, not just a normal mechanic. That's the reason why I go to him.
How can I check if the crankcase pressure is too high? Where to put that Metco breather in? Normally I use full size breather to replace the oil cap. Will an oil catch can helps also?
How can I check if the crankcase pressure is too high? Where to put that Metco breather in? Normally I use full size breather to replace the oil cap. Will an oil catch can helps also?
Thread Starter
TECH Enthusiast
iTrader: (22)
Joined: Aug 2004
Posts: 544
Likes: 0
From: >>>_FRISCO_MUSCLE_<<<
Will my leaking problem goes away if I put in a breather, assuming my installer did the right job? If so, do I need to replace the rear main seal again?
Banned
Joined: Mar 2010
Posts: 334
Likes: 3
I hate to mention this BUT i'll bet its the center plug in the end of the crank. Its easily damaged if someone changes the pilot bearing with the wrong tools. Also could just be leaking because it was damaged or came loose. !st thing i would check before changing the seal.
I had a leak at the back of the motor that I swore was the rear main so I replaced it and still had the same leak, it ended up actually being the back of the oil pan that was leaking.
Points to PCV problems. For a test, clean everything oil-free, remove the oil fill cap and rig up a temporary breather. Go for a ride and see if your seal area remains clean. If so, double check all your PCV lines.
Trending Topics
from what i understand........if you put the seal in backwards......it will leak like a bitch.....i have a new seal to put in myself.....and dont know which is front or back on this bad boy 
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?
Pouria Savadkouei
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo Thread Starter
TECH Enthusiast
iTrader: (22)
Joined: Aug 2004
Posts: 544
Likes: 0
From: >>>_FRISCO_MUSCLE_<<<
I did some tests today. I bypass the PCV valve and connect it directly to the intake. It still leak like crazy. I checked if there's any pressure coming out from the PCV tube, nothing. I even open the oil filling cap and let it idle, same thing.
Here's the symptoms, the oil will start leaking when it reach full operation temperature. If doesn't leak when it's cold. It's leaking between the bellhousing and oil pan. When it starts leaking, oil pressure drops from 60-40 on the dash gauge. It'll leak at idle and leak more when it shut off.
Is that a chance the PCV tube was stuck? I asked a local performance shop and they said put a vent system. What kinda vent system I should put in? Is it possible the rear main COVER screwed up?
Here's the symptoms, the oil will start leaking when it reach full operation temperature. If doesn't leak when it's cold. It's leaking between the bellhousing and oil pan. When it starts leaking, oil pressure drops from 60-40 on the dash gauge. It'll leak at idle and leak more when it shut off.
Is that a chance the PCV tube was stuck? I asked a local performance shop and they said put a vent system. What kinda vent system I should put in? Is it possible the rear main COVER screwed up?
Teching In
Joined: May 2008
Posts: 14
Likes: 0
From: millbrook,al
bump+ check the seal in the back of the crank,those cranks are hollow and the freeze plug seal will leak.They have had tsb from the factory for a while on the ls engine for this prob.when you change out the pilot you will sometimes from just excessive force move it just enough to break the seal.
