I have a 2008 Rav 4. 86000 miles and serviced vigilantly. Before the warranty ran out it had a problem that no one could diagnose so now it’s out of warranty and the problem is a lot worse, still no one has a definite diagnosis. Toyota is not honoring it’s extended warranty, so I will be paying out of pocket so it would be nice to have a better idea of what the problem could be.The rattle was very intermittent at 40mph going up a slight hill. If I took my foot off the accelerator and put it back on the noise went away. Now it is rattling quite a bit and not just at 40mph. I can still have it stop for a bit by taking my foot off the accelerator and putting it back on. My mechanic told me to try driving in 3rd gear. It has not rattled in 3rd gear yet. Toyota mechanic of 29years has never heard this noise before and neither has my mechanic so it is an unusual one. Toyota wants to do a transmission flush 3 times and then if that doesn’t fix it will put in a new transmission. My mechanic thinks it is the transfer case. No one knows for sure. Does anyone have any ideas?
I would look at heat shields on the exhaust system.
Thank you, They looked at that already.
What is being used/not in Drive versus 3rd gear?
One of the first things that I thought of when reading this was…pinging or spark knock.
Most people would describe this as sounding like pebbles rattling around in a tin can.
Does it sound like that?
Admittedly, this condition is much less common than it was years ago, due to electronic engine controls, but it is not unheard of.
If the noise is as I described above, have your mechanic check the operation of the knock sensor and the exhaust gas recirculation valve (EGR), as problems with these items can induce pinging. Also, have him verify that the engine is running at normal operating temperature, because if the engine is running hotter than it should, this can also induce pinging when the engine is under load–as when accelerating or when climbing hills.
Since your spark plugs are due for replacement right about now, I assume that your mechanic has ruled out the spark plugs as the source of the problem, but this is also something to consider.
I don’t see the fix being a series of transmission flushes. If the transmission needs to be serviced, have a proper service on it done, dropping the pan, cleaning/changing the filter, new fluid. You could repeat that 3 times over the course of a month I guess, in order to change out most of the fluid. There’s so manhy things that can cause rattling, it’s all but impossible to speculate. One thing that comes to mind though is to have the engine mounts checked for abnormal wear.