Weird noise going uphill

Maintenance/Repairs
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1

We have a 2008 RAV4 that has been making a weird rattle clunk noise while going uphill lately. The noise is very hard to recreate or get to happen. It seems like it only happens when the engine is more loaded than usual.

I first thought exhaust leak but I can’t find one crawling around under the car.

I also wondered if it could somehow be related to the awd/ 4wd system. My understanding is that it is primarily fwd unless the computer decides it needs to be 4wd then it switches automatically. There is some oilon the rear differential. I can not get it to make the noise anymore frequently when the lock button is pushed than not however.

I am stumped! Do any of you have any ideas?

Thanks

2

The first thing to do is make sure that the noise is not something rolling around , under the seats, a spare tire well, jack compartment etc…

My mother once had a thumping noise and it ended up to be a can that had rolled out of sa grocery bag and under the seat.

Yosemite

3

If the rear differential is leaking, repair that first,

RAV4 differentials aren’t tolerant of low/old fluid.

This may also pique your interest.

http://media.fixed-ops.com/toy_campaigns/Zf4_dlrltr.pdf

Tester