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ms85er

Rear Main Seal Leaks, And Crank Balancing

7 posts in this topic

Hi all,

 

 

Every car I have ever owned (except a commodore) has had a leaking rear main seal. Some of my cars worse than others.

I have a rebuilt 5mge in one of my cars, and it started leaking straight away after the rebuild. From previous research I have herd that rear main seals can leak because of improper fitment, crap seals (crappy brands that come with clutch kits), and also due to crank balancing.

 

Crank balancing is the one that interests me. I want to repair the leak on one of my 4x4's, because it's leaking oil really bad, but to go to the effort to remove the gearbox and replace it, and have it continue to leak after replacing it makes me wonder. If my crank hasn't been balanced properly, is there any way to make the leak stop? Or does anyone have installation tips? because I know for cam seals some people have tricks for installing them like using a punch on the edges to try and expand the seal.

 

 

Cheers

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Well may i say that you must be the first bloke i no that has a commodore that doesnt leak from the rear main (if its a early model).

 

The 4x4 we will need more info like toyota nissan,isuzu.

 

Balanceing would not be the cause of rear main leak,more to do with incorrect fitment old age or rodeo (speaking from experience in rodeos no cure )

 

rob

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You would feel the balancing problem before the leak happened.

 

Old motors leak because the original seal wears a groove in the crank, and the new seal runs in that groove without the help of the dirt and tar that kept the old seal working.

 

I'd worry about the punch because it would cause a local distortion that would leak further around.

 

Overall I have no magic answers, my 4K leaked too! I think they leak to start with then settle down after a few months, either to continue to drip or to seal up.

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Well may i say that you must be the first bloke i no that has a commodore that doesnt leak from the rear main (if its a early model).

 

The 4x4 we will need more info like toyota nissan,isuzu.

 

Balanceing would not be the cause of rear main leak,more to do with incorrect fitment old age or rodeo (speaking from experience in rodeos no cure )

 

rob

 

The car is a 92 4Runner V6 3VZE, hasn't blown a head gasket for a decade now, but now leaking from the rear main worse than ever, was rebuilt about 10 years ago, the leak from rear main probably in the last 2-3 years.

 

 

You would feel the balancing problem before the leak happened.

 

Old motors leak because the original seal wears a groove in the crank, and the new seal runs in that groove without the help of the dirt and tar that kept the old seal working.

 

I'd worry about the punch because it would cause a local distortion that would leak further around.

 

Overall I have no magic answers, my 4K leaked too! I think they leak to start with then settle down after a few months, either to continue to drip or to seal up.

 

Makes sense, so would a small amount of RTV help on the outer edge, speaking of which, where do they normally leak? I imagine on the inner edge around the crank?

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I imagine on the inner edge around the crank?

 

That's what I find, the outer edge is easy to seal with RTV or similar.

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I've replaced a rear main seal on a 3TC and it still leaked. Checked the crankshaft during a rebuild and it had a worn groove.

 

Can get a sleeve that fits over the end of the crankshaft. But an engine builder told me the cheapest way is to use two gaskets for the rear main seal carrier, or no gasket just RTV, and it shifts the position of the lip of the seal on the crankshaft away from the worn groove.

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I've replaced a rear main seal on a 3TC and it still leaked. Checked the crankshaft during a rebuild and it had a worn groove.

 

Can get a sleeve that fits over the end of the crankshaft. But an engine builder told me the cheapest way is to use two gaskets for the rear main seal carrier, or no gasket just RTV, and it shifts the position of the lip of the seal on the crankshaft away from the worn groove.

 

Smart idea, thanks for the info

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