Rear Main Seal Q?

Numbles · Sep 7, 2005

Im on my 3rd rear main seal on my turbo project.

First one I did worked which was my first time ever doing one. When my trans case cracked I sent the car to my mechanic to change the RMS thinking that was it. So he changes the seal and finds the crack in the trans case.

Anyways trans fixed and the new RMS leaked so I put another one in and this one is leaking now. After initial startup it leaked enough to put a small puddle on the ground dripping down the inside of the mcleud block plate. But after idling It doesn't drip. What the heck could the problem be. I lubed the heck out of it with oil before putting it in.

Anyone have any ideas. Or should I take the trans out again and put one of those felpro ones with the extra sleeve on it. Or finish the project and drive it around to see if there is indeed a big leak. Oil pressure was 30 at idle on cold startup FWIW.

Thanks in advance.
Dan.

90bluecoupe · Sep 7, 2005

Are you sure its the rear main seal this time? Sometimes its the back of the intake.It leaks down and you will think its the rear main.

10HoleLX · Sep 7, 2005

Your BIG mistake is when you said "I lubed the heck out of it with oil before putting it in".
Big no no, I always put rear mains on clean and dry. Clean the surface on the block with brake cleaner and wipe the oil seal clean and supper dry before putting it on. Check the block surface for gouges.
Also recommend to use a rear main seal installer to get the seal to go in straight.
Danny.

HardmanGT · Sep 7, 2005

10HoleLX said:
Your BIG mistake is when you said "I lubed the heck out of it with oil before putting it in".
Big no no, I always put rear mains on clean and dry. Clean the surface on the block with brake cleaner and wipe the oil seal clean and supper dry before putting it on. Check the block surface for gouges.
Also recommend to use a rear main seal installer to get the seal to go in straight.
Danny.

Mavrick · Sep 7, 2005

I'd make sure its not the oil pan or intake before going any further. When i did my rear main, i cleaned the surfaces well with brake cleaner, lubed only the outter lip of the seal with oil and tapped it in evenly. No leaks!

EDIT: I also used RTV around the outside of the seal after installed.

HISSIN50 · Sep 7, 2005

One can use RTV around the outside of the seal (metal edge) to help seal it.

Are you sure the crankcase ventillation is up to par. Those symptoms are a little weird - I would want to be sure it is not a positive pressure in the crankcase issue.

Good luck.

Car RamRod · Sep 7, 2005

yea, do you have a breather? A breather should be the first mod for all these cars.

Mavrick · Sep 7, 2005

Car RamRod said:
yea, do you have a breather? A breather should be the first mod for all these cars.

On a fuel injected car? Ya right.. don't post that stupid ****.

HISSIN50 · Sep 8, 2005

a breather on a forced induction car is a good idea if overwhelming the PCV system. Otherwise, as Mav suggests, it is asking for unmetered air on a MAF system (forced induction does not care so much).

5spd GT · Sep 8, 2005

Offtopic: 10HoleLx - Where you been? I haven't seen you on here in a while...good to see ya

I have a nice rear main seal leak...I think mine has something to do with crankcase pressure as well plus just the need for a seal? part number anyone...I lost mine temporarily...I think I have it somewhere...

Car RamRod · Sep 8, 2005

HISSIN50 said:
a breather on a forced induction car is a good idea if overwhelming the PCV system. Otherwise, as Mav suggests, it is asking for unmetered air on a MAF system (forced induction does not care so much).

How? when does crankcase pressure some into contact with intake? If it does then doesnt that mean the pcv is not right?

HISSIN50 · Sep 8, 2005

Car RamRod said:
How? when does crankcase pressure some into contact with intake? If it does then doesnt that mean the pcv is not right?

The flow of PCV air is bi-directinoal. Do you remember that little hose from the oil filler to the throttle body?
It is to allow air to go back into the crankcase (and since it comes from the TB, it is metered air. If it came from the airbox, for example, it would not be metered air). That little filler to TB hose also is an additional crankcase vent at WOT.

HISSIN50 · Sep 8, 2005

Car RamRod said:
How? when does crankcase pressure some into contact with intake? If it does then doesnt that mean the pcv is not right?

Even simpler: The PCV actually sits in the lower intake. It feeds air iback into the intake.

Albrainya · Sep 8, 2005

ck your crankshaft where the seal rides, ill bet theres a groove in it. the way i deal with that is when you put the seal in, dont drive it all the way in, so its not riding in the groove. Ive done that a few times and it works. Or, you can see if a wear sleeve is available for the crank, or you can replace the crank --- also ck your thrust brgs on the crank by doing an end play ck on the crank
hope this helps
Dan

Car RamRod · Sep 8, 2005

HISSIN50 said:
The flow of PCV air is bi-directinoal. Do you remember that little hose from the oil filler to the throttle body?
It is to allow air to go back into the crankcase (and since it comes from the TB, it is metered air. If it came from the airbox, for example, it would not be metered air). That little filler to TB hose also is an additional crankcase vent at WOT.

yea, I get that, but dont you want the extra crankcase pressure to be released, and not pushed into the intake behind the maf?

HISSIN50 · Sep 8, 2005

Car RamRod said:
yea, I get that, but dont you want the extra crankcase pressure to be released, and not pushed into the intake behind the maf?

The blow-by is introduced back into the intake to be reburned (environmentally friendlier than venting via breathers, like you use).

Car RamRod · Sep 8, 2005

HISSIN50 said:
The blow-by is introduced back into the intake to be reburned (environmentally friendlier than venting via breathers, like you use).

Oh, ok.

Numbles · Sep 8, 2005

90bluecoupe - definately the RMS.

10HoleLX - Curious why giving it a little oil would cause a problem. Wouldn't putting it in dry possibly make it more prone to being damaged at first startup on a dry crank.

HISSIN50 · Sep 8, 2005

Car RamRod said:
yea, I get that, but dont you want the extra crankcase pressure to be released, and not pushed into the intake behind the maf?

I think I misunderstood you before. Yeah, we would like to not have dirty air going into the intake. I run an air/oil separator on the 94 to help with this. But the unmetered air thing is an issue for the MAF cars (not so for SD).

Running breathers is cleaner internally (they can be messy externally though) and work great for many folks. The car might run slightly lean though.

Car RamRod · Sep 8, 2005

HISSIN50 said:
I think I misunderstood you before. Yeah, we would like to not have dirty air going into the intake. I run an air/oil separator on the 94 to help with this. But the unmetered air thing is an issue for the MAF cars (not so for SD).

Running breathers is cleaner internally (they can be messy externally though) and work great for many folks. The car might run slightly lean though.

Yea, I mean Im just going with what I was told from a guy who has owned countless mustangs and all that stuff. He told me to put a breather on my car so I did it. Ill see how this rear main lasts.

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