 The timing belt
kfz-tech.de/YMS1
For some time now, people have been complaining on YouTube, for example, about timing belts running in oil, unfortunately with false justifications. No, we won't be able to clear this up
completely, but at least we can straighten out the argument a little.
The timing belt has always been a problematic component. This is due to its crucial function of ensuring that the valves close before the piston arrives. In the past, there was sometimes more
space, so collisions could be avoided.
But that's all old news, as modern engines, even turbocharged ones, have higher compression ratios and therefore less combustion chamber space. In short, a faulty timing belt is almost
always fatal for the engine.
The fact that only valves may be bent is probably also a thing of the past. Only rarely do all pistons escape with minor damages. And thus, what was already an expensive cylinder head repair
becomes an issue affecting the entire engine.
Therefore, the timing belt must not fail. It also took some time to change the design, e.g., the shape of the teeth, until the initially quite narrow intervals could be increased, in some cases even
higher than with timing chains.
The claim that timing belts are only used in inexpensive vehicles is therefore not valid. Even Ferrari engines use timing belts. But back to the topic: What exactly are the problems with timing
belts running in oil?
First of all, the question of how such a construction came about in the first place. The reason for this is by no means just the repeatedly cited lower resistance, i.e. greater smoothness and
thus savings in fuel consumption and emissions.
No, it's a physical issue related to the placement of the oil pump; more specifically, the need to ensure the shortest possible oil intake path. The best location for this pump is as close as
possible to the surface of the oil sump, or ideally, directly within it.
There is hardly anything as damaging to the engine as unreliable lubrication with oil, e.g. due to air in the sucked-in oil. Just imagine if this oil flowed back into the main reservoir from a longer
intake pipe during a period of inactivity.
After starting, the engine initially runs without oil pressure. If someone then foolishly revs the engine, the damage is further compounded. Therefore, the pump should be located in the oil and
driven by the oil flow.After starting, the engine initially runs without oil pressure. If someone then foolishly revs the engine, the damage is further compounded. Therefore, the pump should be
located in the oil and driven by the oil flow.
Previously, when using a timing belt, an additional drive mechanism was necessary. Perhaps eliminating this component even resulted in greater efficiency. In any case, everyone
understands that such an additional drive unit, including an attached oil pump, simplifies the overall design.
The only remaining question was: would the timing belt withstand this? Most likely, a standard timing belt wouldn't last long enough. But you can believe Bosch, for example, that sufficient long-
term tests have been carried out here, even with the inclusion of additional fuel.
Every supplier is extremely vigilant about potential defects, as the OEM will ultimately hold them responsible for the entire cost of any recall. We can't really say much more about this,
except that there are now very simple ways to check for swollen timing belts.
It's surprising that many so-called experts claim to have found pieces of such timing belts in oil channels, given that the oil filter effectively prevents this from happening. Furthermore, the
durability of a swollen timing belt is often underestimated.
But we fully understand that the automotive industry is using this story as an opportunity to promote even more frequent oil changes (what exactly is that supposed to mean?). Fostering fear
has always been good for business.
It is certainly a good idea to avoid buying vehicles with this type of design. However, if you already own such a car, the timing belt is usually relatively easy to access, and its width can then be
easily checked using a wire clamp (video above).
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