Rear Main Seal Leak? Symptoms?
08-08-2008, 12:23 AM
#1
Rear Main Seal Leak? Symptoms? Just rebuilt the bottom end, and I literally fired it up about 2 hours ago. No leaks initially, but after I ran the engine to 200 degrees, I drove her back in the driveway and noticed one drop of oil on the ground, and one little drop on the crankshaft seal housing. So I jacked her up and ran it for another 5 minutes and nothing. Is it possible residual oil on the seals housing as I lubed it before installing?
Anyways, what symptoms are definitely a rear seal leak.
I used the Right Stuff on the Intake, and it has new oil pressure and temp sensors with good teflon, and WIX filter. Oil pan was put on with FelPro one piece and Rigth stuff in all 4 corners.
Anyways, what symptoms are definitely a rear seal leak.
I used the Right Stuff on the Intake, and it has new oil pressure and temp sensors with good teflon, and WIX filter. Oil pan was put on with FelPro one piece and Rigth stuff in all 4 corners.
08-08-2008, 12:29 AM
#2
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A definite rear main seal leak would be oil on the Flywheel/Inspection Cover/Trans (if you drove it, which you did) and you should be able to see it leaking no problem. It could also be residual from when you were working as you only saw one drop.
Put a piece of paper or cardboard on a spot of your driveway you know is not dirty, park the car over it, and run it for 10-20 minutes. If there is a leak, you will know exactly where it is coming from. You could even take it for a ride, and then park it over the cardboard to match exactly what you did before.
Put a piece of paper or cardboard on a spot of your driveway you know is not dirty, park the car over it, and run it for 10-20 minutes. If there is a leak, you will know exactly where it is coming from. You could even take it for a ride, and then park it over the cardboard to match exactly what you did before.
08-09-2008, 12:20 PM
#4
oil will migrate to the lowest point of the motor/car. A leak from up top can appear it is coming from the rear main. The rear main typically does not leak but like any seal/gasket can.
i chased what I thought was the rear main after a engine build only to find it was the rear main seal adapter gasket leaking. Huge PIA to chase it down and then repair with the engine in the vehicle. i had to use oil dye and a UV light to finally pin point my leak.
The most likely sources of your like would be:
rear intake manifold
oil sending unit on rear of motor
oil filter adapter gasket
all those leaks migrate down to the center of the motor and appear to be a rear main
good luck
i chased what I thought was the rear main after a engine build only to find it was the rear main seal adapter gasket leaking. Huge PIA to chase it down and then repair with the engine in the vehicle. i had to use oil dye and a UV light to finally pin point my leak.
The most likely sources of your like would be:
rear intake manifold
oil sending unit on rear of motor
oil filter adapter gasket
all those leaks migrate down to the center of the motor and appear to be a rear main
good luck
08-09-2008, 12:55 PM
#5
oil will migrate to the lowest point of the motor/car. A leak from up top can appear it is coming from the rear main. The rear main typically does not leak but like any seal/gasket can.
i chased what I thought was the rear main after a engine build only to find it was the rear main seal adapter gasket leaking. Huge PIA to chase it down and then repair with the engine in the vehicle. i had to use oil dye and a UV light to finally pin point my leak.
The most likely sources of your like would be:
rear intake manifold
oil sending unit on rear of motor
oil filter adapter gasket
all those leaks migrate down to the center of the motor and appear to be a rear main
good luck
i chased what I thought was the rear main after a engine build only to find it was the rear main seal adapter gasket leaking. Huge PIA to chase it down and then repair with the engine in the vehicle. i had to use oil dye and a UV light to finally pin point my leak.
The most likely sources of your like would be:
rear intake manifold
oil sending unit on rear of motor
oil filter adapter gasket
all those leaks migrate down to the center of the motor and appear to be a rear main
good luck
I am curious, will the rear main seal leak only when running, and constantly, or after a while of running. My oil pressure is around 60 psi cold, so I would think that would make it leak easier as there is more pressure.
08-09-2008, 01:53 PM
#6
The extent of leakage from the main seal is relative to the extent of damage to the seal. With the extensive considerations made by the factory to assure centering of the seal housing around the rear of the crank I would suspect that either the seal may have folded out when the housing was installed, or that there is a groove worn into the sealing surface of the crank. If the seal was folded out and the car was run for any appreciable length of time, the seal will absolutely need to be replaced.
Typically, a main leak will be noticeably worse after the car has run for a few minutes. After the motor is shut down, it will continue to drip for a short time. The oil around the seal is not under pressure. It accumulates in the area of the seal after working it's way out of the rear main and around the thrust bearing. I've only run into main seal leaks occasionally but when I have, there is no doubt about the source of the leak. The puddle is visible very quickly. I've never encountered a leak around the housing gasket but that would be a possibility. That leak would probably result in a smaller volume of leakage.
Good luck.
Typically, a main leak will be noticeably worse after the car has run for a few minutes. After the motor is shut down, it will continue to drip for a short time. The oil around the seal is not under pressure. It accumulates in the area of the seal after working it's way out of the rear main and around the thrust bearing. I've only run into main seal leaks occasionally but when I have, there is no doubt about the source of the leak. The puddle is visible very quickly. I've never encountered a leak around the housing gasket but that would be a possibility. That leak would probably result in a smaller volume of leakage.
Good luck.
08-09-2008, 02:11 PM
#7
I've got one that is shot, I have a puddle right under the rear of the block and enough gets out that it runs down the driveshaft and deposists a second smaller puddle out by the rear end. Also above 3k rpms I can smell oil cooking off in the bellhousing. I took the car off the road, **** can't enjoy it at WOT at the minute.
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08-09-2008, 06:03 PM
#8
Steve40
I have had better luck with the FelPro 'rubber" rear main seal vs the GM one for the LT1
IIRC Metco or kent Moore makes a specific tool to put the rear main seal in. You put the RM seal housing on the block then use the tool to put the seal in. I have used this tool and it is a snap to install the RM seal with it.
I use grease on the seal when i put it on.
The RM adapter should never leak....unfortunately the drunk that put my 1st motor togeather neglected to tighten the bolts or use any gasket sealer.
I have had better luck with the FelPro 'rubber" rear main seal vs the GM one for the LT1
IIRC Metco or kent Moore makes a specific tool to put the rear main seal in. You put the RM seal housing on the block then use the tool to put the seal in. I have used this tool and it is a snap to install the RM seal with it.
I use grease on the seal when i put it on.
The RM adapter should never leak....unfortunately the drunk that put my 1st motor togeather neglected to tighten the bolts or use any gasket sealer.
08-09-2008, 08:49 PM
#9
I use the Kent-Moore tool now although, before I found one of those used on Ebay, I managed by being really careful and making sure that the seal was correctly seated and sliding over the crank surface without folding back. It requires a steady hand and a good flashlight to make sure that it's going on straight.
08-09-2008, 08:56 PM
#10
WHat I did was put the seal in a ziplock baggie. Then I put it in the sun for an hour, prepped the block, put housing on then a little oil. Then it slid right on as the crank was about 60 degrees cooler. I drove it today for a few miles and till oil was at 210 w/ac on. No leaks so far.
Hopefully I am good.
Hopefully I am good.
08-10-2008, 06:21 PM
#12
oil will migrate to the lowest point of the motor/car. A leak from up top can appear it is coming from the rear main. The rear main typically does not leak but like any seal/gasket can.
i chased what I thought was the rear main after a engine build only to find it was the rear main seal adapter gasket leaking. Huge PIA to chase it down and then repair with the engine in the vehicle. i had to use oil dye and a UV light to finally pin point my leak.
The most likely sources of your like would be:
rear intake manifold
oil sending unit on rear of motor
oil filter adapter gasket
all those leaks migrate down to the center of the motor and appear to be a rear main
good luck
i chased what I thought was the rear main after a engine build only to find it was the rear main seal adapter gasket leaking. Huge PIA to chase it down and then repair with the engine in the vehicle. i had to use oil dye and a UV light to finally pin point my leak.
The most likely sources of your like would be:
rear intake manifold
oil sending unit on rear of motor
oil filter adapter gasket
all those leaks migrate down to the center of the motor and appear to be a rear main
good luck
While I agree with all of the above, it could also be at the rear of the oil pan, where it meets with the block. I had the pan off my engine a couple of years ago, while changing the timing chain, and I've had a very slight oil seepage situation ever since. I've been assuming/hoping it's the oil pan, as I'd hate to have to pull the tranny back, in order to do the rear main...In fact, I really don't have the ambition to drop the pan again! I thought the 1 pc. pan gasket was supposed to fix that pesky little problem....
08-21-2008, 06:20 PM
#13
Well, I drove it slowly today through slow city streets to work, and as soon as I parked it a drop of oil fell. Then I turned it off, waited a while and nothing. Then about an hour later there was a little more oil on the wook I left underneath it.
So, I drove it home on the highway at/up to 80 mph with 3,75 gears so it was doing 3000 rpms for a couple miles. Came home, parked it and nothing.
I jacked it up and will cehck it when I get home.The back of the manifold, intake type, is dry. I will look at it again at home, as it is jacked up, and I may run it in the air like that and see if something happens. This is an odd leak.
So, I drove it home on the highway at/up to 80 mph with 3,75 gears so it was doing 3000 rpms for a couple miles. Came home, parked it and nothing.
I jacked it up and will cehck it when I get home.The back of the manifold, intake type, is dry. I will look at it again at home, as it is jacked up, and I may run it in the air like that and see if something happens. This is an odd leak.
08-21-2008, 08:14 PM
#14
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Too bad its not a bad leak, in this case it would be helpful in locating it.
Do you happen to notice any smoke behind you after a good drive (like you described)? This would be a good indicator that the oil is burning off on your exhaust, seen it happen alot and can mask even decent leaks (until you smell/see the smoke of course).
Do you happen to notice any smoke behind you after a good drive (like you described)? This would be a good indicator that the oil is burning off on your exhaust, seen it happen alot and can mask even decent leaks (until you smell/see the smoke of course).
08-21-2008, 11:11 PM
#15
Well, I looked at the area down there. The oil pan has oil between the pan and the blue rubber of the FelPro at the base of the housing of the rear main seal, so not the flat part of the gasket against the block. The Flexplate is dry. There was oil on the housing of the rear main seal, but I couldnt feel any oil on the side of the seal housing where the seal is, and with a que tip barely anything was there. I am thinking it is the pan gasket.
I am going to have to run it, on the jacks and watch it. Then shut it off and see what happens.
No smoke behind me or any burning, and transmission pan is dry.
I am going to have to run it, on the jacks and watch it. Then shut it off and see what happens.
No smoke behind me or any burning, and transmission pan is dry.
08-21-2008, 11:53 PM
#16
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Yeah, that sure is a small one then. A slight oil pan leak in the rear would match what you were describing before perfectly. Be sure to post back with what you find, seems like you got it narrowed down.
08-22-2008, 12:10 AM
#18
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Usually rear mains **** fluid when they really go, so it would be obvious (but it does depend.... could be alot or a little trickle). It might even take a looooong time to get real bad, just might leak a little for a long time.
08-22-2008, 10:58 AM
#20