Replace Non-leaking Rear Main Seal?
Aug 28, 2009 | 11:27 PM
#1
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From: Arizona
Replace Non-leaking Rear Main Seal?
Soon I'll be installing a new clutch. 1986 pickup, 22R, 116K miles, everything original. I presume the RMS and/or trans input seal is leaking because the clutch chatters for awhile at first if it hasn't been driven for several days.
Many suggest replacing the rear main seal while you're in there. However, Marlin posted on his forum:
I'm pondering what to do if my RMS is ok.
Any experiences with this? Have you replaced an old but functional RMS only to have the new one cause problems? Or maybe regret not putting a new one in when you had the chance?
Is this one of those parts worth paying extra (double) for OEM, or are decent brands generally of similar quality?
Many suggest replacing the rear main seal while you're in there. However, Marlin posted on his forum:
4. Rear engine seal.
In almost all cases the rear seal will not be leaking. After removing the clutch assm and flywheel, and then the backing plate, carefully inspect the rear seal around the hub of the crank. Is it actually leaking, or is it the capillary action of the leaking valve cover rear half moon seal that was running down the back of the engine.
If it is not leaking, you have two choices:
A. Replace the good seal;
This is risky business. Remove the rear real, sand the hub of the crank, prelube the sealing lip of the seal and install it being very careful not to damage the seal during installation by hammering directly on the seal body. Then you need to hope that the new seal does not line up and contact directly on the worn area that was caused from the old seal. Never use a stainless steel speedy sleeve on the front or rear hubs of the crankshaft. They are very difficult to install straight, and because the steel is so hard, the seal does not lap in correctly and will always leak in time.
B. Leave the good seal alone;
This is the way Marlin advises. If the seal is not leaking, leave it alone. It has properly lapped in and is doing its job. I leave it until the motor is completely worn out and then you can properly replace it at that time. I have replaced more leaking seals due to customers who have installed a new seal when they did a clutch job. Only to develop a new leak later.
Marlin
In almost all cases the rear seal will not be leaking. After removing the clutch assm and flywheel, and then the backing plate, carefully inspect the rear seal around the hub of the crank. Is it actually leaking, or is it the capillary action of the leaking valve cover rear half moon seal that was running down the back of the engine.
If it is not leaking, you have two choices:
A. Replace the good seal;
This is risky business. Remove the rear real, sand the hub of the crank, prelube the sealing lip of the seal and install it being very careful not to damage the seal during installation by hammering directly on the seal body. Then you need to hope that the new seal does not line up and contact directly on the worn area that was caused from the old seal. Never use a stainless steel speedy sleeve on the front or rear hubs of the crankshaft. They are very difficult to install straight, and because the steel is so hard, the seal does not lap in correctly and will always leak in time.
B. Leave the good seal alone;
This is the way Marlin advises. If the seal is not leaking, leave it alone. It has properly lapped in and is doing its job. I leave it until the motor is completely worn out and then you can properly replace it at that time. I have replaced more leaking seals due to customers who have installed a new seal when they did a clutch job. Only to develop a new leak later.
Marlin
Any experiences with this? Have you replaced an old but functional RMS only to have the new one cause problems? Or maybe regret not putting a new one in when you had the chance?
Is this one of those parts worth paying extra (double) for OEM, or are decent brands generally of similar quality?
Aug 29, 2009 | 05:31 AM
#2
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From: Longmont, CO
I agree with Marlin. If it ain't broke ...
Toyota assemblers are FAR more skilled and have better tools/conditions available to them than we would upside down under the truck.
Replacing a clutch is enough work as it is, you don't need to add anything more to it.
Toyota assemblers are FAR more skilled and have better tools/conditions available to them than we would upside down under the truck.
Replacing a clutch is enough work as it is, you don't need to add anything more to it.
Aug 30, 2009 | 08:17 AM
#5
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From: Texas
I'd have to say if it isn't leaking then don't mess with it.
edit here. When I did the clutch job on mine I inspected the rear main on the engine and the input seal on the tranny, both looked good so I didn't replace anything. Now a few months later my input seal is leaking........... I probably should have replaced both when I was in there.
edit here. When I did the clutch job on mine I inspected the rear main on the engine and the input seal on the tranny, both looked good so I didn't replace anything. Now a few months later my input seal is leaking........... I probably should have replaced both when I was in there.
Last edited by Junkers88; Aug 30, 2009 at 01:35 PM.
Aug 30, 2009 | 10:02 AM
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I guess I was one of the lucky ones. when i replaced my clutch @ 188,xxx mile i had picked up a new seal just in case. mine was dry but decided to change it anyways, after the pilot bearing I carefully removed the rear seal and cleaned out every thing real well, then greased the rubber on the seal and added a little blue permatex tp the outside metal and all is well 
edit: i used a fel-pro seal
edit: i used a fel-pro seal
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Aug 31, 2009 | 04:41 AM
#8
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From: Arizona
xjdubber, how should it be done properly?
What I'd do, problably similar to most others here, is lube the lip with some grease and tap the seal in using a socket of roughly the same size as the outside diameter of the seal. If a socket that big isn't available, work it in gradually using a wood block and a hammer going round and round.
What I'd do, problably similar to most others here, is lube the lip with some grease and tap the seal in using a socket of roughly the same size as the outside diameter of the seal. If a socket that big isn't available, work it in gradually using a wood block and a hammer going round and round.
Aug 31, 2009 | 05:11 AM
#9
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From: Arizona
I'd have to say if it isn't leaking then don't mess with it.
edit here. When I did the clutch job on mine I inspected the rear main on the engine and the input seal on the tranny, both looked good so I didn't replace anything. Now a few months later my input seal is leaking........... I probably should have replaced both when I was in there.
edit here. When I did the clutch job on mine I inspected the rear main on the engine and the input seal on the tranny, both looked good so I didn't replace anything. Now a few months later my input seal is leaking........... I probably should have replaced both when I was in there.
I'm thinking replacement is a good idea if done properly. What's the proper way?
Recently a friend acquired a 1981 CJ-7 with a 258. Among many other issues, the rear main seal leaked. He replaced it, and it still leaked, even more than before. Those engines have a two piece deal installed from underneath, so not exactly what we're dealing with. Turned out he nicked the new seal sliding it in. We replaced it with a new one using more care (which should have been taken the first time), and it is is working fine.
Aug 31, 2009 | 05:57 AM
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xjdubber, how should it be done properly?
What I'd do, problably similar to most others here, is lube the lip with some grease and tap the seal in using a socket of roughly the same size as the outside diameter of the seal. If a socket that big isn't available, work it in gradually using a wood block and a hammer going round and round.
What I'd do, problably similar to most others here, is lube the lip with some grease and tap the seal in using a socket of roughly the same size as the outside diameter of the seal. If a socket that big isn't available, work it in gradually using a wood block and a hammer going round and round.
that seal needs to go in absolutely straight from start to end. a little bit of oil around the outside wont hurt either.
Aug 31, 2009 | 06:02 AM
#11
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I haven't seen any warnings against proactively replacing input transmission seals. Aren't those a similar setup to rear main seals: a seal lip riding against a turning shaft?
I'm thinking replacement is a good idea if done properly. What's the proper way?
Recently a friend acquired a 1981 CJ-7 with a 258. Among many other issues, the rear main seal leaked. He replaced it, and it still leaked, even more than before. Those engines have a two piece deal installed from underneath, so not exactly what we're dealing with. Turned out he nicked the new seal sliding it in. We replaced it with a new one using more care (which should have been taken the first time), and it is is working fine.
I'm thinking replacement is a good idea if done properly. What's the proper way?
Recently a friend acquired a 1981 CJ-7 with a 258. Among many other issues, the rear main seal leaked. He replaced it, and it still leaked, even more than before. Those engines have a two piece deal installed from underneath, so not exactly what we're dealing with. Turned out he nicked the new seal sliding it in. We replaced it with a new one using more care (which should have been taken the first time), and it is is working fine.
Nov 4, 2009 | 06:10 AM
#12
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From: Arizona
Jim Brink (Toyota mech who used to post a lot in toyota newsgroups) said he prefers to apply some Permatex 2B on the outer edge of the seal before installing.
Nov 4, 2009 | 01:58 PM
#13
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From: Longmont, CO
Nov 4, 2009 | 02:29 PM
#14
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From: Leadville Colorado
If your rear main seal isn't leaking why mess with it unless you are confident that you can put a new one in properly? I just did the clutch on my truck and the rear main wasn't leaking so I left it. If it ain't broke don't fix it like EB said.
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