ripratama

I have a Harrier 3.0 Four (RX300 AWD) that drives normally most of the time, except when I floor the gas above 4500 rpm. At that point & beyond, the car emits a harsh & annoying vibration along with some pulsating shriek. When it's idle and cruising normally, it behaves just fine.

It's been difficult for me to locate this vibration. When all windows are closed, the vibration seems to come from the engine bay / behind the firewall but when a window is open, there seems to be a lot of noise coming from below the car instead.

I tried to reproduce these vibrations & noise when the car is in Neutral but didn't manage to produce anything. It only happens when the tranny is in Drive. Sadly, there's no practical way of getting someone to pinpoint the vibration's source from beneath the car while another is driving it at high revs.

The Toyota mechanic told me it's normal and he's seen at least another Harrier with the same problem, also dismissed as normal. I can't accept this conclusion since (a) it only started doing this about 1 month ago, and (b) the red line starts at 6000 and I'm only doing 4500-5000 at most.

So I'm hoping that you guys can help me with most likely causes. Could it be the engine mounts? Timing belt? Belt tensioners? Leaking exhaust joints? Damaged transmission (I hope not)?

Thanks for the tip, guys.

Regars,

Reza

Lexmex

I remember when we went over something similar before. But the vibration you mentioned coming apparently from engine and behind firewall or underneath the vehicle and with a shriek sounds like exhaust. The resonator (fat muffler beneath the vehicle) can make a hum or vibration at very high RPMs. I know because with my exhaust modifications over the years I have had some resonators louder than others. The shriek could come from a tiny exhaust leak. That could come the joint on the exhaust immediately below the engine or at any of the gaskets.

To check on the exhaust leak, one would have to start the vehicle and run the length of the exhaust sensing where hot air is coming out. I had a problem over the weekend as such and had to have a reweld done around the catalytic converter area.

Ideally, you could put the car in Park and step on gas to see if you could recreate vibration in part. Another point that I am keenly aware of is that while you are in the vehicle, it could sound loud, but while you are outside as a casual observer, such vibration will not be readily apparent.

ripratama

Thanks for the advice, Lexmex. I'll try to sense any exhaust leakage later this week.

The vibration & noise don't come out when the car is in Park / Neutral, regardless of the engine being run at +/- 5k rpm. Could it also be the transaxle?

Lexmex

Such noise you might hear all the time from the transaxle if such a noise were to occur not just at high rpms. So I'd probably rule that out.

ripratama

Problem solved! Turned out to be a deteriorated catalytic converter. Replaced it with a custom tubing which should provide similar back-pressure and better performance. While at it, I also added a custom muffler tip. Will post some pics when I'm free.

Lexmex

Far out, will love to see the photos.

jimmouse

Mine has same noise whenever I floor it when entering the highway. Pictures worth thousand of words.
BTW, how much to fix it? Thxs.