As anyone who has ever built and tested prototype engines will vouch, apart from not getting the thing to fire and run, the next nightmare is the steady drip, drip, drip of a fluid on the dyno test bed’s undertray.
Large leaks - whether oil or coolant - are, funnily enough, usually the easiest to solve, where a loose bolt or a forgotten hose clip are generally quickly dealt with. Worse by far though are the slight ‘weeps’ - the leaks that appear out of nowhere, travel down to a joint, run Read more…
In the quest to make engines as oil-tight as possible, we often forget the effect of the humble valve stem seal. Tucked away inside the cylinder head well out of sight, this small, upturned cup of a device grips onto the top of the valve guide and seals against the valve stem, enabling the valve to open and close without letting comparatively large quantities of oil get sucked down the clearance between the stem and guide and into the combustion chamber. With such a small component - and let’s not forget there are generally four of them per cylinder these days - it is therefore very easy to 
Time was when the application of the white of a single egg - be that free range or battery, it didn’t seem to matter which - was enough to cure that annoying little water leak. Dropped into the top of the radiator, the action of the engine being progressively warmed was sufficient to denature the protein in the albumin and form a thick white mass, sealing the leak or at least sealing it enough to get you home. But with modern critically cooled engines, narrow cooling passageways using minimal amounts of transfer fluid, such practices are best consigned to the memories of old men and heroic tales from the past. 
If a shaft spinning at 20,000 rpm can pose a sealing problem then what about one doing 120,000 rpm or even, dare I say it, 240,000 rpm? A simple enough question, you might say, but before answering it we need to understand the application and the desired effectiveness of the seal required.
If you thought it was only race engine manufacturers who are paranoid about friction at the crankshaft seal, think again. The inexorable push towards ever lower CO2 emissions - better fuel economy to you and me - is making many an original equipment (OE) engine component supplier look much more closely at its products.
The interaction between the elastomer seals in an engine and its lubricant is an ongoing battle. Referred to simply as ‘compatibility issues’ by the specialists, the damage inflicted on the seal by the lubricant can manifest itself in two ways. The first of these is considered to be the direct chemical attack on the elastomer matrix resulting in its loss of performance (as a seal) while the second is the combined effect of this and the dynamic stresses applied. While the latter can be addressed by thorough dynamic testing, much of 
As many might know to your cost, the cylinder head gasket is high up among those engine components to suffer the greatest stress. Often a weak point in some of the best engine designs, its unenviable task is to provide a robust seal between the cylinder head and corresponding crankcase for the combustion gases, oils and coolant, both between each other and the outside atmosphere. If that were not difficult enough, the component also acts in distributing the dynamic loads between the head and block and as a consequence, has a considerable influence on the forces 
The humble rotating shaft seal may be an afterthought for many a designer but its history is certainly never lacking in acronyms!
While it might be the aim of many engine designers to minimise the chance of any oil leakage by dispensing with the humble rotating shaft seal, it may not always be possible or even desirable. At any point where there is a mechanical take-off in the form of a rotating shaft, an oil seal will need to be present and while race engine designers try to minimise these occurrences, for the rest of us wishing to improve existing OE equipment or re-engineer old engines, that option simply does not exist. However armed with a knowledge of the design parameters around which these seals perform best, there 
One of the world’s leading race engine manufacturers has revealed their design philosophy regarding seals and gaskets to RET Monitor this month.
