Toyota-Lexus-Subaru-Honda Timing Belt Contigencies

When quoting a timing belt replacement, there are a number of contingencies that will be unknown until we’re well into the job. For instance, the timing belt bearings may still be functional and essentially symptom free.

However, once the timing belt has been removed, we can spin the bearings while feeling them and listening to them. If a timing belt bearing is beginning to sound worn-or even just dry, as if it’s lost its lubrication-then that’s the time to replace it while it’s so accessible that there’s no labor required.

On the other hand, if the timing belt bearings feel and sound good, we feel completely comfortable reusing them.

We also check the drive belts. Of course these can typically be assessed before any work has begun. The drive belts tend to last longer than the timing belt, but not nearly as long as two timing belt lives. If the drive belts are the same age as the timing belt, it’s probably not a bad idea to just go ahead and replace them preemptively while they’re off even if they’re in decent enough condition that you wouldn’t otherwise need to replace them.
As far as the water pump goes, some of our recommendations are contingent on the vehicle. For instance, the 3 liter and 3.4 liter V6 engines in the trucks and 4Runners have such a history of leaking that it seems like a good idea to replace them preemptively even if they don’t show any signs of leaking. On the other hand, the water pumps on the 1MZFE V6 engines in Camrys and Siennas have such a good record of longevity that I don’t feel at all uncomfortable if a customer is inclined to reuse one of these for another timing belt life cycle. Of course anytime a water pump is actually showing signs of failure, if its eventual replacement is dependent on removing the timing belt, then by all means replace it while the timing belt is off.

The front engine oil seals-for the crankshaft, the camshafts, and the oil pump-are all accessible while the timing belt is off. If any of these are leaking, then I most often advise that they all be replaced at the same time since the rubber seals have all had the same number of miles and years to age. I used to never suggest these seals be replaced preemptively, but I have a growing bias toward replacing them. Although sometimes they make it through a second timing belt life cycle, too often they won’t successfully make it through the duration without leaking oil and you’ll end up having to pay to remove the timing belt again to access to the seals.

Sometimes the seals have gotten hard and will have cut a groove into the sealing surface. In this case, we need to install a seal-surface repair sleeve in order to assure that the new seal is able to engage and seal properly. This grooving can happen to any of seal surfaces that involve a shaft rotating past a seal. It happens more frequently to the crankshafts than to the camshafts, because the crankshaft turns at twice the speed of and twice as many rotations as the camshafts. When the grooving happens to the oil pump gear shaft, then the oil pump gears need to be replaced, which typically isn’t a very expensive part.