340 rear main seal leak/gush

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Dan the man said:
Glad you got it to stop. Was the pan gasket re useable? I've known about off setting of the rear main seal for a long time
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OMG. A brand new rebuild that was NOT a rattle can rebuild. Leaking!!! :BangHead::BangHead:
 
Newbomb Turk said:
Dan, I’m one of those guys who’d tell you that not all of us clock the seal offset like that.

You need to learn to fit the rear seal rather than offset it.

Think of that seal like a bearing and then tell me if you’d ever offset a main bearing like that and why you’d do it.
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Well Turk, It's a seal not a bearing. I've put together 11 engines since 2009. Mine and some friends. Always used a Superfomance "pink" rear seal and always clocked them 3/8 offset.
Not one has ever leaked a drop. Way back then, Rick @ Superformance told me that's the way ya do it. So I considered his advice gospel. I was brand new to Mopar.
 
Ironmike said:
Well Turk, It's a seal not a bearing. I've put together 11 engines since 2009. Mine and some friends. Always used a Superfomance "pink" rear seal and always clocked them 3/8 offset.
Not one has ever leaked a drop. Way back then, Rick @ Superformance told me that's the way ya do it. So I considered his advice gospel. I was brand new to Mopar.
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It’s not a bearing but it has crush LIKE a bearing.

If you fit the seal correctly you don’t offset it.

That came from a 1995 Felpro sealing seminar I had to go to.

If you are offsetting a two piece seal you need to find out why it’s leaking if you don’t. And it’s not that the seal is leaking at the split.

It’s because the seal is too proud and it gets over crushed and the seal deforms.

Offsetting the seal doesn’t fix that, but it’s a hack that half assed works.

The correct installation is fitting the seal.

I love Superformance gaskets but he’s wrong on that.
 
Newbomb Turk said:
It’s not a bearing but it has crush LIKE a bearing.

If you fit the seal correctly you don’t offset it.

That came from a 1995 Felpro sealing seminar I had to go to.

If you are offsetting a two piece seal you need to find out why it’s leaking if you don’t. And it’s not that the seal is leaking at the split.

It’s because the seal is too proud and it gets over crushed and the seal deforms.

Offsetting the seal doesn’t fix that, but it’s a hack that half assed works.

The correct installation is fitting the seal.

I love Superformance gaskets but he’s wrong on that.
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ALL OF THIS is correct!
 
Newbomb Turk said:
It’s not a bearing but it has crush LIKE a bearing.

If you fit the seal correctly you don’t offset it.

That came from a 1995 Felpro sealing seminar I had to go to.

If you are offsetting a two piece seal you need to find out why it’s leaking if you don’t. And it’s not that the seal is leaking at the split.

It’s because the seal is too proud and it gets over crushed and the seal deforms.

Offsetting the seal doesn’t fix that, but it’s a hack that half assed works.

The correct installation is fitting the seal.

I love Superformance gaskets but he’s wrong on that.
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Show us the correct way to fit the seal.
 
70SwingerGuy said:
Has anyone ever run into this before?? I cant figure out what could have caused that substantial of a leak.
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Have you done a CC pressure test yet?
If it's the oilpan, you'll know right away,
also check the distributor to block interface.
After the easy tests are done,
Drop the inspection cover and listen for air escaping in the BH, There's several places back there that can gush oil.
During the Air test, the VCs have to be sealed, and I pressurize thru the dipstick. I set my regulator to no more than 4psi. You never know how tight the rear cam plug is installed, and if it blows out, don't say I didn't warn you .................
BTW
The oilpan is in fact off a 340 right. and
for sure not off a 360, right.
I mean, I had to ask.
 
Newbomb Turk said:
Dan, I’m one of those guys who’d tell you that not all of us clock the seal offset like that.

You need to learn to fit the rear seal rather than offset it.

Think of that seal like a bearing and then tell me if you’d ever offset a main bearing like that and why you’d do it.
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I've never in my life offset the seal and knock on wood have never had a main seal leak.
 
Newbomb Turk said:
Yeah, the way you fixed it is best.

Offsetting the seal effectively keeps the seal from getting the proper crush.

If you have a seal leak, and you offset it and it seals you reduced the crush. In other words, the seal is getting too much loading on its ends because those ends are too proud of the cap and block.

Correctly fitting the seal (both halves) for proper crush and the seal won’t need to be offset to not leak.

I tried to get into a conversation with DTM but he is convinced that offsetting the seal is the proper fix so I didn’t waste my time trying to show him that just because people are doing something doesn’t make it right.
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If offsetting was the proper way, I'd be in every factory service manual ever printed. It's not.
 
@ Newbomb Turk, I asked you to show me the proper way to install the seal and you never replied. I'd be glad to have a conversation with you, I'm open to learning to do thing's correctly.
 
Some seals force you to do it this way, quite successfully .
Clean surfaces, no goop, - none.
Dozens done with either style, line bored or not.

IMG_20240802_082213.jpg
 
Well. Call me wrong. But I'm gonna continue my wrongness as long as a Superformace seal is involved.

I can tolerate a lot, but NEVER a drop or drip of anything. Not my cars, my truck, tractors and especially my body!:D
 
Ironmike said:
Well. Call me wrong. But I'm gonna continue my wrongness as long as a Superformace seal is involved.

I can tolerate a lot, but NEVER a drop or drip of anything. Not my cars, my truck, tractors and especially my body!:D
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I can even tolerate a little leaking from
my body but I detest oil leaks from any point. Drives me nuts, which doesn’t mean much because my wife says it’s a real short drive to crazy if you me.

And I don’t like losing either, ergo I don’t argue with her. I hate hate hate losing.
 
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I’ve had problems with seals not being the true dimension so I’ve been using a little black rtv between the seals and the block and cap serfaces , so far so good.
 
My intention was not to start a uproar over the installation of a seal, I just was saying what I did in the past and it worked I'm not saying that it's the right way or the wrong way to install the seal. I don't remember how many I have offset or how many I put in the normal way. I will say this for sure, it's important that all surfaces be cleaned and inspect the seal for defects.
 
Dan the man said:
My intention was not to start a uproar over the installation of a seal, I just was saying what I did in the past and it worked I'm not saying that it's the right way or the wrong way to install the seal. I don't remember how many I have offset or how many I put in the normal way. I will say this for sure, it's important that all surfaces be cleaned and inspect the seal for defects.
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See post 22 Dan.

This is why it’s just not worth it to tell people there is right way to do **** because they’ve done it wrong forever and it works so they keep doing it despite overwhelming evidence.

There is a correct way to fit a two piece seal. Offsetting isn’t it.

But carry on. It works right?

Superstition is a bad way to build engines.
 
Newbomb Turk said:
See post 22 Dan.

This is why it’s just not worth it to tell people there is right way to do **** because they’ve done it wrong forever and it works so they keep doing it despite overwhelming evidence.

There is a correct way to fit a two piece seal. Offsetting isn’t it.

But carry on. It works right?

Superstition is a bad way to build engines.
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No, I've learned the better way to do things.
 
Dan the man said:
No, I've learned the better way to do things.
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Dan, if you learn only one thing from me, I hope it’s to not take MY word for anything more than a bullshitter on the internet.

Take my words for NOTHING.

What I want you to learn is question everything, assume nothing and VERIFY EVERYTHING.

Then you will KNOW you are doing the best thing at that time.

Things change and evolve, so what we do today may not be the preferred way in 10 years. Or 5. Or even 2.

So verify what anyone tells you. I do that by calling the engineers who do this stuff when I have questions.

Go to the website I posted and watch all the free webinars they do. You can’t pay for an education like that.

Another one is epartrade.com. They are well over 150 webinars now and the topics vary widely.

Go get the Taylor books, the two volume set read it. I can’t remember the exact name of the books now but it’s Charles Fayette Taylor. Look it up.

The upshot is just because I say something is the right way to do it, don’t just accept that as gospel.

Get on the phone and verify that stuff. From multiple sources.

Then you can go out to the shop knowing you’ve done your best to learn the best to be the best you can be.

Don’t take my word for anything. Always verify.
 
Newbomb Turk said:
Dan, if you learn only one thing from me, I hope it’s to not take MY word for anything more than a bullshitter on the internet.

Take my words for NOTHING.

What I want you to learn is question everything, assume nothing and VERIFY EVERYTHING.

Then you will KNOW you are doing the best thing at that time.

Things change and evolve, so what we do today may not be the preferred way in 10 years. Or 5. Or even 2.

So verify what anyone tells you. I do that by calling the engineers who do this stuff when I have questions.

Go to the website I posted and watch all the free webinars they do. You can’t pay for an education like that.

Another one is epartrade.com. They are well over 150 webinars now and the topics vary widely.

Go get the Taylor books, the two volume set read it. I can’t remember the exact name of the books now but it’s Charles Fayette Taylor. Look it up.

The upshot is just because I say something is the right way to do it, don’t just accept that as gospel.

Get on the phone and verify that stuff. From multiple sources.

Then you can go out to the shop knowing you’ve done your best to learn the best to be the best you can be.

Don’t take my word for anything. Always verify.
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Thanks, I appreciate this
 
I offset the rear main seal if its one of the old rope seals, but I am a hobbyist not an engine builder (so probably doing it wrong).
On a SBM I just put a tiny dot of the right stuff on the ends of the seal and a thin smear where the cap meets the block - no leaks so far.
 
Ted265 said:
I offset the rear main seal if its one of the old rope seals, but I am a hobbyist not an engine builder (so probably doing it wrong).
On a SBM I just put a tiny dot of the right stuff on the ends of the seal and a thin smear where the cap meets the block - no leaks so far.
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On a rope seal it’s not a bad thing.
 
Had an oil leak at the back of the oil pan once (in the pan itself), A little JB Weld fix it. Just had to remove a couple quarts of oil first. A little engine paint, good to go.
 
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