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Leaking Seals

2K views 20 replies 8 participants last post by  kilgorq 
#1 ·
I have a 1985 Mustang 5.0 motor that I had rebuilt and balanced several years ago. It has about 5000 Miles on it and I have had issues with it since it was rebuilt. It leaks oil out the Front and Rear Main Seals.

The Re-builder put a speedy sleeve on the crank because there was a grove on it. It still leaks. I replaced the Harmonic Balancer and it still leaks.

PCV and Breather are in place and function properly. I have replaced both " Just in case"

The transmission has been pulled 2 times to confirm that the rear seal is the source of the leak and it definitely is.

I can let it sit and Idle all day if I want and it will not leak a drop of oil. I can vary the RPMs with it sitting in the garage and still not a drop of oil. If I put it in gear and take it for a mellow drive I may get a little tiny drop on the floor when I get back home. If I go Drive it like it should be. burn through the gears and have some fun. It smells like burning oil and I get several big drops of oil on the floor when I get home. There is no blue smoke coming from the exhaust. but you can see that the oil has been getting on the exhaust under the rear seal. And the sway bay will be coated with oil.

I Pulled the plugs today and they look really good. The only thing I could find was the the Plug from Cylinder 2 was a little wetter looking than the rest. If I was not being really picky I would call it a great looking plug.

A compression test shows almost no deviation between the cylinders. As expected since it is a New motor.

My thoughts are the I have excessive pressure building in the crankcase causing the oil to get pushed past the seals. But I might be barking up the wrong tree. I am making no headway on this and need ideas on ways to narrow it down. I really do not want to have to pull the motor and tear it apart for an inspection but I am starting to think that it is the only thing left to do.

I did move the "Wetter" Plug to a different cylinder and will drive it tomorrow and inspect again to see if 2 is "wetter" again. But i really think that it was a little wetter because it was on the intake stroke when I shut it off.

It consumed "Lost" 2 Quarts of oil in about 1000 miles. When it leaks it leaks a lot.
 

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#3 ·
It is pretty easy to burn a seal up in a minute. All you gotta do is install it dry. I always use a good lubricant on the lips of the seals and on the seal surface. It is especially important when using speedy-sleeves. The added pressure at the seal needs lube to keep them working until they get oil splashed on them.
 
#5 ·
I always lube the seal and the mating surface with fresh oil. If I remember correctly I actually used the same assembly lube I had for the lifters. I also replaced the rear seal the last time I had the transmission out. I have used grease on some because it holds better until the seal gets lubed by the motor.
 
#6 ·
High crankcase pressure is a possibility, has it ever pushed out the dipstick?

Shot in the dark. Was the motor line bored? Have you tried removing the dowels on the rear seal adaptor and front cover and allowing the seals to center themselves on the journals.

Another option is dual lip seals or offset seals.
 
#7 · (Edited)
it never has pushed the dipstick out.

Motor was not line bored.

I have not torn it apart and checked to see if crank is centered properly. I am assuming that is the intent of removing the dowels. If it was not centered wouldn't it leak all of the time?

Dual lip oils seals might be an option. If the issue is crankcase pressure wouldn't they leak too?

Someone suggested that the crank may have been ground off center. I don't know how you would tell. Unless you are looking at how the crank is centered in the motor. I did look at the how the front seal was centered to the crank when I replaced balancer and it looked good. That was not with a micrometer, that was just with the naked eye and looking at how the balancer lined up with it.

What causes excessive crank pressure besides compression leaking into the crank (Bad or incorrectly installed rings, Or a crack in the cylinder or piston.)

And if that is the case why only under power.
It is not like I am running a 400 horse motor either. 250 tops with my setup. Stock heads, Stock intake, Edlebrock 600 and 2.5" dual exhaust with full length headers and an x-pipe.
 
#8 ·
The only thing you haven't done is replace the seals front and rear?

Replace them?

Seems like the rebuilders issue unless you did the assembly.

To me sounds like the garter spring is missing on both, seen them come out of the box like that or someone forgot to reinstall them once the seal was pressed in.

Seen it before.
 
#10 ·
He did the rear and I did the front. He put the motor together to the long block level. I put the timing cover, valve covers, intake, and oil pan on.

He replaced the rear seal 1 time. I have not replaced the front seal. I will probably try the seals one more time. I am sure the garter spring is in the front one but not sure about the rear. Since I didn't put it in.

This motor was actually rebuilt about 12 years ago and driven for about 4000 miles. Then sat on a stand up until I put it in my 69 mustang. I don't think the sitting has anything to do with the issue because it was there before it sat.
 
#9 ·
do you have a vacuum gauge.. many range from 15 pounds of pressure to 30 inches of vacuum.. hook that to the dipstick tube.. stick the gauge under the wiper.. take it for a ride.. you should NOT build pressure in the crank case.. you should not build vacuum in the crankcase.. max of either would be 1 pound of pressure and 1 inch of vacuum.

you can test the PCV valve for proper calibration for your engine.. with a DIGITAL Tachometer hooked up. engine warmed to operating temp.. . block the PCV flow.. you should loose between 50 and 70 RPMs .. if you loose less than 50.. you need a slightly larger flowing PCV valve.. if you loose over 70 rpms. you need a slightly smaller PCV..
 
#11 ·
I will give the vacuum gauge a shot before I replace the seals. I tried it before and the needle did not move. I think if it was working I should have seen some action on the needle. I didn't try it while driving.

A digital tach would be nice but not something I have.
 
#12 ·
After installing a Sleeve on the crank, you still must install the timing cover seal properly centered on the crank. The factory usually installs centering bushings or dowels on the engine block that serves to align the timing cover seal with the crank shaft front snout.

If the front crankshaft seal in the timing cover is not centered on the crank, it will leak oil and there is nothing you can do to prevent it.
 
#13 ·
The sleeve for the front of the motor does not go on the crank. A sleeve is used in the timing cover area to get out of replacing the harmonic balancer. I have never seen centering bushings or dowels used on a 302 for anything you mention here. if the crank is not centered there are only a couple ways to re-center it that I know of.

1 Replace the crank (It was ground wrong)
2 Replace the block (It was line bored wrong)

if the timing cover seal is not centered with the crank then you have a bad timing cover, bad harmonic balancer, defective seal, or an crank that is not centered.

The Sleeve was installed on the rear main of the motor due to the oil leak by the re-builder. His thought was maybe there was enough of a groove to make the seal not seat properly. The sleeve should have fixed it. Unless the crank is off centered or there is excessive crankcase pressure forcing the oil passed the seals.
 
#18 ·
Its been a while but I finally got up the nerve to tear into it and look. Bad News... Cylinder one is scored. Now I am not happy at all because I actually paid extra money to have the builder assemble it to the long block point. He either left some debris in the motor or was not able to get these out from prior to the rebuild but did not want to loose the money.

I am thinking if since I am going to have to scrap this motor I want to go with something more modern with fuel injection. Does anyone have any suggestions on good combo's in my 69 Mustang coupe.

Please I would like to hear about things people have done and been happy with. Not the "that would sound cool ideas". This is not limited to ford engines either.

No 4.6 I don't like them. Too physically large for the cubic inches. If I wanted to put something the size of a 460 under my hood it would be a 460. Actually the 4.6 is bigger than a 460.

Ford 4.6L SOHC

Dimensions: 28-5/8 inches wide, 28 inches long, and 26 inches tall
Weight: 600 pounds
Sump Location: Front
Starter Location: Right
NOTE: Width is valve cover to valve cover. Height is to top of valve covers.

Ford 4.6L DOHC
Dimensions: 30 inches wide, 28 inches long, and 29-7/8 inches tall
Weight: 576 pounds
Sump Location: Front
Starter Location: Right
NOTE: Width is valve cover to valve cover. Height is to top of valve covers.

Ford 429-460
Dimensions: 27 inches wide, 30 inches long, and 29 inches tall
Weight: 720 pounds
Sump Location: Front
Starter Location: Right

Sorry if I come across badly. My mood is sour tonight.
 

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#20 ·
2 Looked pretty good. Actually all of the rest of the cylinders looked pretty good. 7 looked like the top ring may have not seated well. But not enough to cause concern. The scratches in cylinder 1 are deep. Deep enough to catch your fingernail in them. I am going to pull it all apart and look a lot closer but I think the block is done, Once I pull it I will take it to a machine shop and get a second opinion. This thing that baffles me is that I did a compression test and it looked really good. With the scratches in cylinder one I would have thought the compression would have been lower than the rest.

I did notice what looked a little bit of piston wobble at the bottom of cylinder 2. But I could not get it to do it again. I think the only way to figure out exactly whats up with that is to pull the piston out and look at the piston and cylinder.

I am worried about getting another 5.0 since they are getting really had to find. Unless you are ready to spend a lot of money on a man o' war block. On the other hand converting over to something else would be quite the chore too.

Here is a picture of 2.
 

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