It sounds like the timing belt is rattling, but the timing belt isn’t due for another 25,000 miles. Could it be bad already?
What is the vehicle? 2000 Toyota Rav4
How many miles? Just over 65,000
Do you know if the timing belt has ever been re-tensioned? No, I don’t believe it has.
Diagnosis by phone: The timing belt is probably OK, it just needs re-tensioning.
Inspection/diagnosis: Well, when I got my hands on this vehicle it indeed was making the typical noise of a loose/worn timing belt. The first thing I did was to attempt to re-tension the timing belt since this engine has that capability. Once the timing belt was re-tensioned I started the vehicle. The noise continued although it seemed a little bit quieter. Ok, out comes the stethescope. I checked around and again, the noise seemed to be originating from the timing belt slapping against the timing belt cover. Looks like this one needs to come apart for further diagnosis. It could be one of the idlers making the noise, but I won’t find that out without removing the covers.
Final diagnosis: Removed the timing belt covers to find that the timing belt tensioner was 100% engaged, but the belt was still loose. Ok, so the belt has stretched. The tensioner pulley is tight and doesn’t spin freely. Also, the water pump is seeping.
Solution: Ok, so the belt needs replaced as well as the tensioner spring, and the tensioner pulley. We should also replace the water pump since it only adds a small amount of labor. Once I get the go-ahead from the owner I’ll update on the results of the parts replaced.
Results: I got the go-ahead from the customer to replace the water pump, timing belt, tensioner idler, tensioner spring and the crank seal. Once those parts were replaced the rattle at the front of the engine went away. After delivery the customer reports that the engine runs smoother and seems to be stronger. The conclusion there would be that the belt was stretched enough that the timing was jumping around making it inefficient and therefore creating a power loss and a rough running condition.