Since I have been working on solving chronic oil leaks on this car, I'd like to share my experiences with readers. But first a broad look at sealing. Sealing is a science on which the industry spends millions in research and development. Having said that if one does a bit of research on various car forums and web sites one finds that opinion is broadly split between the three following methods of sealing two metal halves:
A - Use of sealing compound with gasket.
B - Not using any sealing compound with gasket
C - Just use sealing compound without any gasket.
In the case of group 'A' there is a further sub division who say use a hard setting compound and those that say it should be soft setting. In the case of group 'B' there is also a sub group supporting the use of gaskets dry and the other saying apply grease to gasket. The fact is that all of the above are going to do the job. Each of the above have their pros and cons.
All a bit confusing really. When I work on any equipment, car or other, I always follow the manufacturer's guidelines. A habit developed after 30 years of working in the area of maintenance in the industry. More often than not using "jugar" lands one in trouble.
There is no one particular method of sealing that works in all situations. Factors like temperature, service, environment all dictate the type of sealing method. My experience has taught me that in the case of cars, if there is a metal to metal joint (without gasket) use a soft sealing compound and if you have a metal to metal joint (with gasket) just use grease – no sealing compound.
Generally speaking hard setting compounds fail over time as they are prone to cracking and are a real pain to clean later if you open up the equipment. In trying to scrape off the hard set compound one runs the risk of ruining the metal sealing surfaces.
Specifically in the case on this project car, the service manual is silent on the use of any sealing compounds. Perhaps because in 1948 there was no such thing. In the factory when the car was being assembled, they used dry gaskets or at most a thin smear of grease or oil on the two metal faces that press the gasket. In this case the gasket is oil/water/petrol resistant paper. Use of oil/grease makes the paper swell up and offers better sealing. Of course the bolts have to be torqued up to the specified level and always in a cross pattern. Cross pattern bolting makes sure that the metal sealing faces come together evenly. With paper gaskets, I have observed that one needs to re-torque the bolts after a few hours. I suppose that may be due to the paper settling down
