Rear Main Seal - cause of failure shortly after install?

[NIZLAH]

Ok long story short, rebuilt 4age 16v in my gti ae92, just got it in and running over the weekend, after a quick lap of my street I discovered a chronic oil leak between bellhousing/block... rad not...

Anyhow pulled gearbox off this morning and found my rear main seal (which was brand new genuine) to be almost all the way out of the housing... rad not...

It was installed properly/straight, my exact procedure was that I put the seal face down on a flat surface and pressed the housing over it so the face of each was flush and level, a little bearing lube was used to aid the install....

Wtf happened to make it fail like it did? does the seal need to be pushed deeper into the housing past the face? that's the only thing I can see be a factor, not much else can change really.. Ive done a few rear mains and never had a drama before?

Cheers for any insight

Niz

[Gunner]

bearing lube

it should a couple mm in from the face. if it was flush it wasn't in all the way. so that plus the bearing lube, and it would of pushed itself out the first time it got full oil pressure

[NIZLAH]

So don't lube the outside face of the seal at all when installing?

[Matt]

I normally push them in with a 1/4" extension bar.. start at 12 o'clock, then 6, then 3, then 9 and work my way around until it is in.

The clutch plate will also be soaked in oil, and may cause issues with the pads.

[Gunner]

only lube the inner of the seal, where the crank turns.

[NIZLAH]

sweet, cheers gunner, all I needed to know.... Matt, clutch is sweet, no oil to be seen on it nor the flywheel surprisingly so all good there... I prefer to push them in with equal pressure on the complete surface

[maxhag]

What Gunner said...... I only lube the inner seal edge on those type of oil seal rings

[Lexsmaz]

Have you taken the box off to see what went wrong as in is the seal still in place ?? as has been said ideally no lube should be used on the outside & also I keep an eye on how easy the seal goes in & if it goes in very easy I put a smear of silicone on the very outside face outer edge to housing rim, just a bit of piece of mind ... As has been said you must put a smear of grease on the complete seal lip & even a light bit on the crank too ..

[Willofan]

I am surprized no one has mentioned excessive oil pressure from a stuck/seized relief valve in the oil pump. The rear main is the weakest link above 80psi
Did you notice anything on the guage when you went for your run around the block??

[Lexsmaz]

Engine Oil pressure wont push out the seal as the crankshaft rear main bearing journal & the rear seal are not on the same plain, but crankcase pressure from blow by etc Will push out the seal ..

[Vance]

i do rear mains everyday. i use assembly lube on the outside of the seal to get it in easier. i use excessive o-ring and seal lube on the inside of the seal.

most common causes of failure is not enough lube on the inside or putting the seal exactly where the previous seal was. usually you get a worn mark on the crank from the last seal. push the seal further in or not as far in to avoid the mark.


that all said, the last 4a rear main i installed leaked like crazy. replaced the seal using the same method but didnt push the seal as far in. still leaked like crazy. couldnt be bothered to do it again and after a week it stopped leaking. i used toyota genuine seals.

[NIZLAH]

I am surprized no one has mentioned excessive oil pressure from a stuck/seized relief valve in the oil pump. The rear main is the weakest link above 80psi
Did you notice anything on the guage when you went for your run around the block??

on that note could it be anything to do with the pressure relief valve in the factory oil filter sandwich plate? as it was removed and re fitted, done right as far as I'm aware though, all by the manual,

[NIZLAH]

i do rear mains everyday. i use assembly lube on the outside of the seal to get it in easier. i use excessive o-ring and seal lube on the inside of the seal.

most common causes of failure is not enough lube on the inside or putting the seal exactly where the previous seal was. usually you get a worn mark on the crank from the last seal. push the seal further in or not as far in to avoid the mark.


that all said, the last 4a rear main i installed leaked like crazy. replaced the seal using the same method but didn't push the seal as far in. still leaked like crazy. couldn't be bothered to do it again and after a week it stopped leaking. i used toyota genuine seals.

Hmm interesting, this was an epic leak though, I have an oil trail that goes up and down my street twice, into my driveway and also faintly extends to the local caltex.....

Don't think its an oil pressure issue as pump is a brand new genuine unit... Crank was polished so old seating from previous seal is prob not a huge concern, I will re install without lube and push it in a extra mil or 2 and see what happens

[Lexsmaz]

Don't re-use the seal that is leaking though .. Replace it

[NIZLAH]

Don't re-use the seal that is leaking though .. Replace it

that's a given

[timbo]

Bit of bad luck! Check that the metal face is smooth too.

[lolwat]

never use lube on the outside, and if the car has a issue(blow by etcetc) ill glue the seal in with loctite

last bigport i pulled out of my ke70, when i pulled the flywheel off the seal fell on the floor(huge amounts of blow by) know exactly when it came out too

[NIZLAH]

Loctite ay, which one? would using a small amount of permatec grey on the outer edge be a bad idea? (only because I have it)

[Gunner]

there is a specific one for it from memory, perm grey will do the job

[lolwat]

basically what ever we have had at work or at workshop

[NIZLAH]

replaced it with a Kelpro seal from repco, was half the price and interestingly enough it was about twice the depth/thickness than the genuine one so it had more meat to grip, used some perm grey also, yet to install gbox so will see how it goes in the coming week or so

[Lexsmaz]

Had the seal popped out or was it leaking from the lip ??

[NIZLAH]

Had the seal popped out or was it leaking from the lip ??

Popped out..

[driftke70]

if the seal has been sitting on a shelf for ages or in the sun they can go hard and oil itself wont make them nice and soft and fluffy. Stop smoke or stop leak in your oil even a tiny bit works pretty darn well.
I have bought motorcycles that have been in storage for 5 or more years that leak like a Indonesian illegal vessel and a capful of stop smoke/leak in the crank case fixes it in the next ride. Never to be needed ever again. When i fit rear mains I make sure they are nice and fluffy if they aren't you can rub stop leak right on the seal. Also I use a socket on an extension which has been put on backwards which is the same diam and tap the socket with a mallet and get it in straight.
If you put it in at an angle and catch it straight it makes it squiff and will probably leak prematurely. I have never put any lube on the inside of the seal. The engine is full of oil. The seal is in direct contact with oil. Only thing any kind of lube would do is make it easier for it to be cut on reassembly.

If it makes you sleep at night go ahead.

[driftke70]

Also i use seal cement on the outside.