Help,My 912 Rear crankshaft seal has always oil leak..

[Antony Mann]

Hi
Im Antony from Hungary,
I have 912 from 66'
All engine was rebuilt by my self.
Sure,the rear crankshaft -fly wheel side-seal also we changed.
If the engine running 5 min,the oil leak coming..

I to bougt in 4-time new seal,brown-black-blue..japan,Germanian,and hungarian produkt..better,stronger....but the oil just coming..

Perhaps,do you have any idea?...maybe need the bolt also change?...I have 3 size washer,the crankshaft not to move,I can adjustable.

thx for any advice
Antony Mann

[Peter Graham]

Antony,

There are several things that come to mind as far as the leak:

• There are a lot of double-lipped seals available: if you use one of these, the lip nearest the flywheel must be trimmed off flush to the seal. If the second lip is left in place, the seal will fail in short order. (25/36Hp single-lipped VW Viton seals are available - my personal preference; p/n 111.105.245 from Wolfsburg West)
• A new soft iron gasket must be used upon removal of a torqued gland nut.
• You will not find this in any manual: when you are ready to torque the gland nut for the final assembly, saturate the dowel pins with wicking ('green') Loctite 290.

Good looking motor!!

Hope this helps!
Peter

[Antony Mann]

Ok Peter,
I try it..
I to bought now the faoumus "Viton" seal..in my country the mentioned seal is cheap,cost is 10$
Thx
Antony

[Gunzel]

Antony
The real problem is probably that the flywheel has a grove worn in it from the seal. Check the part of the flywheel that fits into the seal if there is a grove worn in it you need a replacement flywheel. You may be able to machine the flywheel and remove the groove ( if there is one ) but if you remove to much it will reduce the sealing surface to much and the seal will really not work.

mike curnow

[Antony Mann]

Mike
Thx for your answer, and advice.
The flywheel like a new, without any worn, "standart grosse".
The problem is was joking:Bad oil!
Actualy,I always usd 15W30.. Never problem with a rebuilt engine.
All bearings, seals,etc...new.

Now 5W-40...the problem resolve.
Its crazy..

[Peter Graham]

Antony,

I had a similar issue using 5W-40 synthetic. The issue was mostly resolved by changing to 20W-50 Valvoline VR-1, a petroleum-based oil ('dinosaur oil'). The VR-1 formulation has enough ZDDP to support 'flat tappet' motors (although US emissions is cracking down on ZDDP content). There are other dino oils with high ZDDP content (Motul, others). The trusted engine builders here recommend 20W-50 weight petroleum-based oil with higher ZDDP levels.

I went through 4 oil seals on my current motor (built with parts from two motors, over 50K miles since August 2012) trying to solve the final small leak problem.


I am currently rebuilding the original motor: Ol Smokey Rebuild. Both motors use Scat crankshafts which I hope is not the source of nagging main seal leaks...

Peter

[Ivory 912]

Some thing like these wear sleeves could help

DuraSLEEVE Home: Shaft Sleeve : Hard Chrome Sleeve : Sleeve Vancouver : Shaft and Yoke : Dura Sleeve : Oil Seal : sleeve : Repair Sleeve