Of the many gaskets and seals in an engine, probably the most annoying and terrifying in equal measure, when it fails, is that at the mid or lower liner. On dry-liner engines this doesn’t exist of course, so the product developers can sleep soundly at night. But in wet-liner designs this seal can be the greatest source of nightmares, because when it fails the area is so inaccessible. As ever, it always boils down to issues such as manufacturing cost and trying to keep things simple. But simple doesn’t always mean reliable, and Read more…

What is the difference between a sealant and an adhesive? You may be thinking that this is a trick question, with a clever single-word rejoinder, but I can assure you that nothing is further from my thoughts. You see, when it comes down to it, the difference between a sealant and an adhesive can often be one of intent. The sealant is present to prevent the passage of a liquid (or gas), while the adhesive is more about mechanical strength and retention. Read more…

Although many might disagree, the sealing of the gap between two fixed surfaces is a relatively simple task. Variation in loading or changes in thermal expansion may require the joint to have some form of compliance, but in general the solutions are well understood and, as such, failures should be few and far between.

But when it comes to sealing the gap between a rotation crankshaft and the engine crankcase, a wholly different Read more…

The modern internal combustion engine is a masterpiece of engineering. Whether gasoline or diesel, intended for road or race track, the complexity under the hood can be a little awe-inspiring even to those familiar with the technologies used. So why, when we have engineering development processes like FMEA, Six-Sigma and the like, do we still build engines that after only a few short months or even days can still leak oil out of the crankshaft rear oil seal? Owners of the big-block Chevy engine, or indeed those using many other older-type Read more…

As an engineer you must always be looking to improve the product, whether it be to improve its performance, increase reliability or simply make it easier and hopefully cheaper to manufacture. The general term for all this activity is development, and although now a dirty word in any engineering organisation - since it implies that the design wasn’t correct in the first place - the sealing of the combustion gases at the split line between the cylinder liner and fire face has always been the subject of much of this activity. Read more…

Historically, the rear main bearing oil seal has always been a challenge for the engine designer. Ask any modern competitor of a classic or vintage racecar when apart from getting the engine started in the first place, the second most important quest is to keep the oil where it belongs - in the sump and not on the garage floor!

Hidden out of sight somewhere between the rearmost Read more…

Isn’t it strange to think that what we regard today as being ‘obvious’ wasn’t quite so obvious in the early days of race engine design. Take the head gasket, for instance. Today’s young engineers are almost conditioned to think in terms of separate castings for the combustion chamber and valves, and that of the cylinder-supporting structure. But in days gone by, the very idea of having separate components bolted together with apertures where engine coolant, oil and combustion gas crossed must have been totally unthinkable. Read more…

“Ensure that the gasket is in good condition” is a phrase commonly found in the workshop manual. Anyone rebuilding an engine or transmission with the assistance of such wise words will probably recognise the phrase, but while we often spend much hard-earned cash buying new internals, the temptation as far as the gaskets are concerned is to try wherever possible to use the old ones. We know it’s wrong, evidence of a cheapskate or even a miser, but nevertheless we still do it - and sometimes even get away with it. Read more…

I know it’s hard to credit it, but before 1937 the ‘O’ ring didn’t exist. Patented in that year by Danish immigrant to the US, Neils Christensen, an ‘O’ ring, while eminently simple in concept, is in practice a very powerful sealing mechanism. No wonder they can be found in any number of critical applications inside most purpose-designed race engines. At the base of the cylinder liner, around the body of the fuel injector and at the top deck of the cylinder block sealing oil and coolant as it passes into the cylinder head - these are all critical areas where a Read more…

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…