MinorForum

Morris Minor Chat

Crankshaft Oil Seal

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

KevinB Kevin Baker
Auckland, Balmoral, New Zealand   NZL
Hi, I have a 1960 Morris Minor which is suffering from a slight oil loss by the engine back plate. I suspect that the crankshaft oil seal may need replacing.Is it possible to remove the gearbox, back plate and replace the oil seal without removing the motor from the car.
Regards

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
John in Eugene Avatar
John in Eugene Gold Member John Quilter
Eugene, Oregon, USA   USA
How much is slight? How big in diameter is the spot left on a clean non absorbent surface after a full warm up and drive and left parked for 2 hours? Keep in mind these A series engines have no real "seal" at the back of the crankshaft, it is only a scroll which is supposed to wind the oil back into the crankcase. The amount of leakage is very dependent on the amount of blow by in the crankcase. Later USA spec Minors had a positive crankcase ventilation system for emissions reasons and these tended to keep a slight vacuum on the crankcase that minimized leakage at the scroll seal. I have retrofitted these to a Minor and MGTD with very good results.

John F. Quilter
Eugene, Oregon USA

emjay Jim English
Marietta, PA, USA   USA
To answer the other part of your question is yes. It is possible to do all that work under the car with the gear box removed but it's awkward and in reality there isn't much you can do unless one of the rear seal kits on the market can be installed in place. Removing the gearbox and worse reassembling it under the car requires tipping, rotating, pulling, and other forms of wrestling. A big deciding factor can be the gear box cross member. It needs to be removed, so you need to know the workable condition of the bolts that hold it in place. If their floating nuts break loose, you will be taking the floor out and the master cylinder if the driver side needs to be repaired. To go out the common way by removing the grille everything is simple bolts except the hockey stick trim on the side. The nuts are a bit awkward and the studs often break, but the overall operation is easier. The another alternative is take the engine but leave the gear box. I did it once by just removing the radiator. Getting the gear box shaft out of the clutch takes some manipulating and can be a bit brutal.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
kiwiminor ray willis
prince albert, Saskatchewan, Canada   CAN
Kevin,
Oil from the rear-main-seal on a M/M is common due to the reason John Q has described. You aren't the first one to drop oil on the Auckland roads, I did it too in the late-60's and 70's.
The best fix is the device which Gerard has available and no doubt he will contact you or the Forum in due course. Further scanning on previous Forum-inquiries of the same matter should confirm this.
Ray W

0123 Mike D
Biddulp, Staffs, UK   GBR
The square cork seal at the
back of the sump may the
cause of your leak Kevin.

Apart from that, the period
fix was to connect the rocker
box breather to the space
between the filter and carb.

Thereby reducing pressure
inside the crankcase.

There was a Works valve
but generally speaking
it were not very good.

And now it's umpty years older
a bit weaker in the spring and
a bit stiffer in the diaphragm sad smiley


Attachments:
ferd.pdf    294 KB

0123 Mike D
Biddulp, Staffs, UK   GBR


Attachments:
ferd.pdf    502.1 KB

pixelsmithusa Avatar
As has been stated, the inline A-series engines do not have a true seal, but rather what is called a scroll seal. An explanation of how that works can be found here on my web site.

http://gerardsgarage.com/Garage/Tech/SealKit/SealKit.htm

The requirements to make the original are very demanding and specific. The air gap that needs to be maintained between the crankshaft scroll and the main cap/half moon seal has a very minute tolerance of .0004" to .0015". This is approximately the thickness of cellophane you find wrapped around a cigarette package. Over time, there will be wear on this surfaces and the gap will be beyond tolerance. This can only be restored with a line bore of the block. This requires complete disassembly of the engine to be done in a machine shop. This needs to be done with the main caps and rear half moon piece above the rear main cap in place and never removed or repositioned thereafter. An additional factor to this failure of the scroll seal doing it's job is excessive internal engine pressure called "blow-by". This is a symptom of loss of performance of the piston rings. Again, this requires machine shop work to correct. The internal pressure can sometimes be mitigated with the addition of a PVC setup, but the one that works the best for this is the Smith's valve used in later British cars. Sometime this works, and sometimes not.

Don't bother removing the engine or gearbox to facilitate a repair unless you plan to retrofit the seal kit shown at the link above. It's the only one made that actually works.

You can read more about it in this independent and unsolicited endorsement.

http://www.mgexp.com/phorum/read.php?3,2681890,2681890#msg-2681890



Gerard

http://gerardsgarage.com/

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
0123 Mike D
Biddulp, Staffs, UK   GBR
How much bearing wear will your
seal kit tolerate please Gerard?

pixelsmithusa Avatar
I don't understand your question? Do you mean the shell bearings? Why do you think this is even an issue? Much more than the crank or rods will tolerate!

In reply to # 24861 by 0123 How much bearing wear will your
seal kit tolerate please Gerard?



Gerard

http://gerardsgarage.com/

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
0123 Mike D
Biddulp, Staffs, UK   GBR
You answered my question perfectly
when you said your seal kit will tolerate
"Much more (wear) than the crank or rods will tolerate"

Which strikes me as a bif plus where
a potential customer has a well leaky
rear seal and no wish to recon just yet thumbs up



Edited 1 time(s). Last edit at 2017-07-14 06:49 AM by 0123.

pixelsmithusa Avatar
Exactly, but more than that, though not ideal, this seal kit can be retrofit with the engine in the car. I have done it a couple times this way, but much more desirable to do on a bench instead, and more likely to be installed properly. The point though is that it does not require complete disassembly of the engine, and much more economical than an engine rebuild, which is your point. However, it will not make up for a well knackered engine.

In reply to # 24864 by 0123 You answered my question perfectly
when you said your seal kit will tolerate
"Much more (wear) than the crank or rods will tolerate"

Which strikes me as a bif plus where
a potential customer has a well leaky
rear seal and no wish to recon just yet thumbs up



Gerard

http://gerardsgarage.com/

0123 Mike D
Biddulp, Staffs, UK   GBR
Thanks Gerard smiling smiley

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions

Members Sign In   or   Create an Account

Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster





Join The Club

Sign in to ask questions, share photos, and access all website features

Your Cars

1963 Morris Major

Text Size

Larger Smaller
Reset Save

Sponsor Links