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Rattle sound coming from engine @ 2,500 rpm in 6th Gear

I have this strange noise coming from the engine area when on the highway going about 100 KM in 6th gear. It happens when I am about running about 2,500 RPM and the rattle starts after 30 mins of driving and then when putting a bit of throttle down you can hear the rattle kicking in and then going off.

I've heard some others say its because the engine is under strain, but it really shouldn't happen if the whole point of being in 6th gear is to save on fuel.

I am trying to find a sound clip that I can reproduce the noise and I hope someone might have had a similar noise. My warranty runs out next month need to get it fixed if it gets worse after June. Toyota has said if its a major issue it doesn't matter if the warranty expires it can be fixed at the manufactures cost.

I actually heard a similar sound from the game GTA 1 back in 1997 so I'm trying to pull the sound effect and dump it on youtube for others to here.

Please let me know if anyone had this issue.

Quote:

Originally Posted by FRS2017 (Post 3090447)

I have this strange noise coming from the engine area when on the highway going about 100 KLM in 6th gear. It happens when I am about running about 2,500 RPM and the rattle starts after 30 mins of driving and then when putting a bit of throttle down you can hear the rattle kicking in and then going off.

I've heard some others say its because the engine is under strain, but it really shouldn't happen if the whole point of being in 6th gear is to save on fuel.

I am trying to find a sound clip that I can reproduce the noise and I hope someone might have had a similar noise. My warranty runs out next month need to get it fixed if it gets worse after June. Toyota has said if its a major issue it doesn't matter if the warranty expires it can be fixed at the manufactures cost.

I actually heard a similar sound from the game GTA 1 back in 1997 so I'm trying to pull the sound effect and dump it on youtube for others to here.

Please let me know if anyone had this issue.

If it a high pitcged metalic soumd like rocks in a tin can then its like knock. Australian fuels are pretty crap and western aistralian fuel seems bad. You are running a premium brand 98 like shell or bp, and not Costco or something ?

It's more of a dull rattle sound, I am using 98 octane fuel all the time every time from Caltex (Woolworths). Happens at low rpm and as soon as I have it in high gear it goes away.

it's very similar to this:

[ame]https://www.youtube.com/watch?v=6Px6TQoA8s0[/ame]

Noise seems to point to the word rod knock (I really hope not):

[ame]https://www.youtube.com/watch?v=Tb6oAm2f76U[/ame]

Recently I had my car in for a major service and the technician or car mechanic spotted that my idle pulleys where corroded and the bearings had gone. In total, I have had all three idle pulleys replaced and to my surprise, it has fixed the rattling sound after 30 mins of driving in low gear. Amazing, even Toyota didn't know what to think about it.

The car mechanic was surprised that the idle pulley bearing had gone after 30,000 KLM, but it did and now I have no strange rattle noise.

I have one going bad in our Forester with less than 50k miles on it. I'm going to change both and the belt as long as it has to come off anyway. I am disappointed that it went with so few miles but what are ya gonna do...

Quote:

Originally Posted by FRS2017 (Post 3283418)

That is odd...3 idler pulleys. The same pulley, right?

Pulley bearings usually only go bad prematurely when the belt tension is not correct. Both too tight and too loose are an issue. This is why manufacturers switched to automatic tensioners, which cannot be adjusted as far as I know.

The spring pre-load in the tensioner may not be designed correctly. So it's possible we may see a TSB for the serpentine belt tensioner eventually...

deleted because I didn't watch the videos, I had another sound in mind.