Re: Rear main leak. Oil pressure too high?

bbf-falcon February 22nd 2015, 8:55 pm

I was taught to rebuild engines as a very young teenager in the 60's by my invalid Dad,and a ole reliable "Motor repair Manual" that spec'd repairs from the manufactures . It and my dad told me to overlap the rear main seal.It's always worked well for me.Thats why I overlap it.

dfree383 February 22nd 2015, 10:08 pm

DaveMcLain wrote:
the Coug wrote:Jim I have seen what they do on main caps and when you butt the flush with the cap they seem to mushroom out and under the main cap, when you stagger the slightly they don't mushroom.

Let's see a picture of this phenomenon that you're describing, I've never seen such a think and I still say that messing around with staggering the ends of the seal makes zero difference.

Probably a hold over from the old school rope seals, some urban legends die hard.

hienergy557 February 22nd 2015, 11:02 pm

Are you sure it's engine oil? Could also be trans fluid, either from a converter seal of a crack in the centre spigot/boss. I've had that happen before.
I'm with Lem, 75 psi should not be a problem.

ROAD RAGE February 23rd 2015, 12:13 am

Cam Plug?

ianxy351 February 23rd 2015, 3:17 am

Will be checking cam and gallery plugs when we get it out of the car. Thanks for all the comments and suggestions - its all really appreciated.

Ian

Gregaust February 23rd 2015, 6:00 am

I normally use a little grease on the seal to make sure it stays lubed before startup..

Here's a thread you've prob seen http://www.460ford.com/forum/showthread.php?t=135753&referrerid=25042

ianxy351 February 23rd 2015, 8:02 am

Read the thread. Thanks Greg. Think I read it a while ago but forgot about it. What is the story with needing to put sealer on the top left bell housing bolt. I haven't heard of that before.

BigRigTech February 23rd 2015, 10:22 am

I always stagger mine, just something I was taught to do...Don't fix what ain't broke I guess. Wink

I usually put some lubriplate 105 on the seal lip to give it something for start up.

Dave C. February 23rd 2015, 10:28 am

Check for a leaking galley plug. The oil will run down and look like a seal leak.

Lem Evans February 23rd 2015, 10:58 am

As much drain area as there is in the cap, between the bearing and the seal, I don't see the seal seeing near the pressure that the bearings do.

rmcomprandy February 23rd 2015, 11:18 am

ianxy351 wrote:The only installation issue I can think of would be too much crush. I haven't been in the habit of checking rear main crush in any of my previous engines but have read recently that too much crush can lead to leaks. Prior to the rebuild it was dry so it is either too much crush or oil pressure. My 351C runs happily all day at 75psi but maybe there is some nuance with the BBF that I am unaware of? I'm hoping I can find the problem and that it's not going to require the engine to come out.

We run an Moroso vacupan system.

Ian

Excessive crush seems to be an issue and a big problem with a lot of the rear seals out in the marketplace today.
Especially when the mains have been line honed or bored.

I don't think it would be "spraying" oil if there is a seal of any kind in there but, oil "throw-off" from a spinning crank sure does happen.

Doug Rahn February 23rd 2015, 11:19 am

ianxy351 wrote:What is the story with needing to put sealer on the top left bell housing bolt. I haven't heard of that before.

That bolt penetrates the lifter valley and can be the source of an annoying mess.

Rear main leak. Oil pressure too high? - Page 2 BellhousingBoltPent_zps645088cf

Rear main leak. Oil pressure too high? - Page 2 BellhousingBoltPent_zps645088cf

ianxy351 February 23rd 2015, 3:44 pm

Thanks for the photo Doug. I remember seeing that now. I will put some sealer on the bolt.

I had a thought last night that may be relevant. I still think that there is most likely a problem with the rear main seal, however, when I rebuilt this engine one of the issues we had was oil surge on deceleration. Part of my solution was to remove 2 of the oil gates at the rear of the box section around the oil pickup to remove any restriction on deceleration so that oil could get to the pickup from the back of the pan. We are using a moroso rear pickup pan. So, there are 2 front gates installed to stop oil running forward when the car decelerates but no gates at the back so I wonder if the rear main is getting a great big rush of oil coming at it as the car leaves the start line and accelerates? The two rear gates shouldnt be a problem in my mind because of the overall volume of oil in the sump at the start of a run (it hasnt all been pushed to the top of the motor at that stage), but it is a difference between this set up and the pre-rebuild set up that may be worth thinking about.

gt350hr February 23rd 2015, 7:45 pm

Ford shop manuals call for the seal ends to be offset. I too have seen the rubber squeeze out and keep the cap from fully seating.

ianxy351 July 4th 2015, 3:31 am

Well, it's taken a while to get the time to do the rear main but we opened her up today. I'm ashamed to say that the problem was me. I'm a goose. I installed the bottom section of the seal back to front. What an idiot. All fixed now. Sorted a couple of other previously unknown issues with the motor and its on its way back with its owner tonight to go back into the car this week.

Thanks all for the suggestions and help.

maverick July 4th 2015, 6:36 am

rmcomprandy July 4th 2015, 10:44 am

DaveMcLain wrote:
the Coug wrote:sounds like someone didn't stagger the rear main or put it in backwards.....there is no direct pressure to the rear main seal it has a void in the lower main cap which lets it flow out to the pan...

I've never figured out how "staggering" the ends of the seal could make any difference what so ever in how the seal functions, please explain.....

Staggering the seal, perfectly aligns the groove in the cap to the groove in the block so the ends of the seal are in alignment, every time.

Almost sounds like a cam plug is missing here or the seal is installed backwards.

rmcomprandy July 4th 2015, 10:47 am

rmcomprandy wrote:

Almost sounds like a cam plug is missing here or the seal is installed backwards.

I should have read the entire thread first ... Rolling Eyes

Although, seal crush can be an issue a lot of times. Especially with a line honed block.

Another thing I have seen with A460 blocks, around the era when they changed vendors, is that the rear cap does not have oil return holes drilled in it from the front of the seal area.

res0rli9 July 5th 2015, 1:47 pm

ianxy351 wrote:Well, it's taken a while to get the time to do the rear main but we opened her up today. I'm ashamed to say that the problem was me. I'm a goose. I installed the bottom section of the seal back to front. What an idiot. All fixed now. Sorted a couple of other previously unknown issues with the motor and its on its way back with its owner tonight to go back into the car this week.

Thanks all for the suggestions and help.

Well... What did you find???

maverick July 5th 2015, 3:33 pm

ianxy351 wrote:Well, it's taken a while to get the time to do the rear main but we opened her up today. I'm ashamed to say that the problem was me. I'm a goose. I installed the bottom section of the seal back to front. What an idiot. All fixed now. Sorted a couple of other previously unknown issues with the motor and its on its way back with its owner tonight to go back into the car this week.

Thanks all for the suggestions and help.

ianxy351 July 5th 2015, 4:56 pm

res0rli9 wrote:
ianxy351 wrote:Well, it's taken a while to get the time to do the rear main but we opened her up today. I'm ashamed to say that the problem was me. I'm a goose. I installed the bottom section of the seal back to front. What an idiot. All fixed now. Sorted a couple of other previously unknown issues with the motor and its on its way back with its owner tonight to go back into the car this week.

Thanks all for the suggestions and help.

Well... What did you find???

Bottom half of the seal was facing the wrong way.

res0rli9 July 5th 2015, 5:39 pm

Maybe they just wanted to keep 1/2 the dirt,rain water & anything from get into it Rolling Eyes

gt350hr July 6th 2015, 3:50 pm

looks like the Coug was right again.

dfree383 July 6th 2015, 4:15 pm

gt350hr wrote: looks like the Coug was right again.

He's not elegant in his presentation...... But he is right a lot of the time

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