Timing Belt Contingencies

When we replace a timing belt, we also replace the parts that are bundled with it: the timing belt bearings and tensioner, the water pump (when it’s driven by the timing belt), the drive belts and the front engine oil seals for the crankshaft, camshafts and oil pump.

We used to make case-by-case judgment calls on many of these parts. If a bearing felt and sounded good, or a water pump had a strong track record, we were comfortable reusing it for another timing belt life cycle. Over the years, though, we’ve come to believe that replacing them preemptively is the better plan, for a few reasons.

First, these parts are all right there while the timing belt is off, so replacing them adds little or no labor. If one of them fails later, the timing belt has to come off again, and you end up paying that labor twice.

Second, the rubber seals, bearings and pump have all had the same number of miles and years to age. A part that’s still working today isn’t necessarily going to last through another 90,000 miles. Seals in particular often don’t make it through a second timing belt life cycle without starting to leak oil.

Third, a failing bearing, tensioner or water pump can damage the new timing belt or cause it to derail. On an interference engine, that can mean catastrophic engine damage.

Finally, we warranty our timing belt jobs for 3 years or 36,000 miles. Replacing the related parts at the same time means the whole system starts out fresh, not just the belt.

Even so, some things can’t be known until we’re well into the job. When the old seals have gotten hard, they can cut a groove into the sealing surface of the shaft. In that case, we need to install a seal-surface repair sleeve so the new seal is able to seal properly. This happens more often on the crankshaft than on the camshafts, because the crankshaft turns twice as fast. When grooving happens to the oil pump gear shaft, the oil pump gears need to be replaced, which typically isn’t a very expensive part. We may also find damage from a past oil or coolant leak that needs attention. If we find anything like this, we’ll contact you to explain what we found and go over the cost before we go further.