The task of sealing joint faces falls to gasket cement… doesn’t it?
All old bikes leak oil, it’s their charm… er no, they don’t have to, and with the help of Loctite we show you how top stop them dripping.
The whole hoary subject of replacement gaskets, sealers and the like is one close to the heart of any reader of this magazine. After all, most of the motorcycles we use are at least 30 years old and the cases have been apart loads of times.
Gasket cement is a product designed to hold a gasket in place before being fitted. Like many people, I’ve been guilty in the past of misusing the products we glibly describe as gasket goo, thankfully though I’ve not been as bad as the owner of an engine I was once asked to have a look at because ‘…it stopped working…’
One glance showed why – ribbons of orange silicone exuded from every joint face on the engine and the situation didn’t improve the deeper I went in. Every single oil-way and gallery was full of the stuff and the lad had apparently used two whole tubes of the goo to stop any oil leaks. A result he had, in fact, achieved.
What he had missed was that instant gasket, gasket cement or assembly silicone can only do its job properly if the lightest smear is applied to an already flat jointing face. Ladling the stuff on with a trowel may well seal the joint but you can guarantee if the cement squeezes out of the side then it will squeeze out inside the engine too, where it can cause damage.
We’ve mentioned many times how to make sure mating faces are as flat as possible in a home workshop, by rubbing them on an old mirror with a smear of fine grinding paste on it – but it doesn’t hurt to say it again. Nor does it hurt to say the grinding paste must be washed off thoroughly, as you don’t want that getting inside your engine.
For the next bit of the feature we’re indebted to Henkel Ltd for providing us with Loctite products and instructions on how to use them to the best advantage.
As you can see, the engine we’re using is just bare cases, so we can show things a little more clearly where the joint faces are.
The world of gaskets and instant gaskets has moved on a long way and thanks to people such as Henkel, with Loctite there is little reason why an older motorcycle shouldn’t be as oil-tight as a modern one. Above: A selection of engine cases typical of themachines seen in CDB. From the left, the old cases fromour project IT, then the new project 3TA/5TA and our first project Rotax/canam