Thump from hybrid (like a bass drop)

[ShottsCruisers]

I am not completely convinced on the Lexus mechanics answer and want to verify.

Can someone explain how this works "IF it does this when the engine is RUNNING then I'd have somebody lube the driveshaft zerks (EASY) to eliminate that being an issue. "

The specific condition under which sound occurs is when the car is normal accelerating from a stop....and happens a fraction of a second after the vehicle starts moving (almost like something is moved by the forward momentum of the car and hitting something). This sound is different from when the engine kicks in due to autostart/stop. It occurs when engine is already running and you normal accelerate then a fraction of a second later there is a dull low volume thump sound....the sound is consistent in nature and I dont think it varies with how hard you accelerate so it is likely not being something loose in the car and bumping back due to forward momentum of the car. Normally, if something was loose, the thud timing and volume would vary ever so slightly based on how you accelerate....

But I want to understand this driveshaft zerks thing....and under the specific lens of knowing that the sound occurs just a fraction of the second after the car starts to move.

As the suspension lifts and lowers under bumps, braking, accelleration, the drive shaft moves...it lengthens and get shorter depending. Lube keeps it smooth. If there's a problem, then when you take off the shaft doesn't smoothy move. Instead it pops from one position (length) to another thus a bump or thud. And it'a a PITA.

 

[garyculb18]

My son got one of the 1st Toyota RAV 4 Hybrids. The noises this thing makes are pretty awful/rediculous. He warned me hat all Hybrids from Toyota do this so, I was prepared for the worst.

All I can say is "Turn Up the Radio & Rock On." It did seem to get better as I pushed the SUV and it got used to my driving behavior.

In my option one can no longer listen to the engine on a Toyota Hybrid and figure out what is wrong with the vehicle.

Best, Doc

 

[jupfl561]

I am not completely convinced on the Lexus mechanics answer and want to verify.

Can someone explain how this works "IF it does this when the engine is RUNNING then I'd have somebody lube the driveshaft zerks (EASY) to eliminate that being an issue. "

The specific condition under which sound occurs is when the car is normal accelerating from a stop....and happens a fraction of a second after the vehicle starts moving (almost like something is moved by the forward momentum of the car and hitting something). This sound is different from when the engine kicks in due to autostart/stop. It occurs when engine is already running and you normal accelerate then a fraction of a second later there is a dull low volume thump sound....the sound is consistent in nature and I dont think it varies with how hard you accelerate so it is likely not being something loose in the car and bumping back due to forward momentum of the car. Normally, if something was loose, the thud timing and volume would vary ever so slightly based on how you accelerate....

But I want to understand this driveshaft zerks thing....and under the specific lens of knowing that the sound occurs just a fraction of the second after the car starts to move.

I'm having the exact same issue. Did they ever figure it out? Lexus mechanic said it was my first aid kit moving around. SMH.

 

[Tangopapa]

It's not been figured out. I am living with it. Someone somewhere commented that its when the electric drive engages in addition to the engine when you go from stop to accelerate...seems plausible....

 

[ShottsCruisers]

OK gang...let's put this to bed. This is completely NORMAL. No driveshafts, no this or that. Simply put your display onto the setting where you can see the tachometer. You'll see the tach drop to off (0 RPM) every time the engine gets shut off from coming to a stop, going downhill, decelerating, etc. Then you will notice the "rumble" or "thump" or "whatever" every time the tach kicks back in as the electric motor starts the gas engine. This is yor "proof" of the cause of the sound some are reporting. So watch the tach as it tells the story. IF...IF you hear the rumble, thump, whatever when the ENGINE IS RUNNING then you have some sort of an issue...but I bet you don't experience this. Watch the tach with your ears. LOL

 

[Webbcorp]

OK gang...let's put this to bed. This is completely NORMAL. No driveshafts, no this or that. Simply put your display onto the setting where you can see the tachometer. You'll see the tach drop to off (0 RPM) every time the engine gets shut off from coming to a stop, going downhill, decelerating, etc. Then you will notice the "rumble" or "thump" or "whatever" every time the tach kicks back in as the electric motor starts the gas engine. This is yor "proof" of the cause of the sound some are reporting. So watch the tach as it tells the story. IF...IF you hear the rumble, thump, whatever when the ENGINE IS RUNNING then you have some sort of an issue...but I bet you don't experience this. Watch the tach with your ears. LOL

Thank you! Thank You!We got ours April 25. On test drive I noticed this 'thump'. Both my wife and the salesman said they didn't hear anything. This makes complete sense! Man... can't tell you how much I appreciate this. Knowing I am not hearing things and knowing our Lexus is ok, it's normal.

 

[ShottsCruisers]

Thank you! Thank You!We got ours April 25. On test drive I noticed this 'thump'. Both my wife and the salesman said they didn't hear anything. This makes complete sense! Man... can't tell you how much I appreciate this. Knowing I am not hearing things and knowing our Lexus is ok, it's normal.

Yep! The dealers are used to the hybrid's function as they have many models. No big deal to them. The dead giveaway is to WATCH YOUR TACH...it tells the truth. RUMBLE! LOL

 

[hilljf]

I have had mine for a year now and if this sound exists it does not bother me. I do hear the high pitch of the hybrid from time to time and the engine does have a unique rumble. I find the transition from hybrid to engine power to be exceptionally smooth.

John

 

[LX700hovertrail]

Got my 2026 LX700H Overtrial last month. Already drove around 3K Miles. Great car but really dissapointed in Hybrid system. Turns on/off twenty times within a mile if you are in slow traffic or rush hour. Very annoying and takes away the luxury aspect of this 120K vehicle. Also definitely making a thumping sound everytime engine turns-on/off from battery to engine or vice versa. Took it to a Lexus dealership and there standard response was "thumping sound is normal". Asked for an official email so I can open a complaint with Lexus corporate. There tone changed, manager got involved and now I have an open case with Lexus engineering. As of now they think its the exhaust thats making thumping sound everytime engine turns on/off. They are suggesting "insulator for the exhaust pipe". Once installed I will give you all an update.

 

[ShottsCruisers]

Got my 2026 LX700H Overtrial last month. Already drove around 3K Miles. Great car but really dissapointed in Hybrid system. Turns on/off twenty times within a mile if you are in slow traffic or rush hour. Very annoying and takes away the luxury aspect of this 120K vehicle. Also definitely making a thumping sound everytime engine turns-on/off from battery to engine or vice versa. Took it to a Lexus dealership and there standard response was "thumping sound is normal". Asked for an official email so I can open a complaint with Lexus corporate. There tone changed, manager got involved and now I have an open case with Lexus engineering. As of now they think its the exhaust thats making thumping sound everytime engine turns on/off. They are suggesting "insulator for the exhaust pipe". Once installed I will give you all an update.

Sorry you're not happy. But I suggest you spare yourself some grief and dealer trips. This is 100% normal. Nothing is wrong. And no insulator or whatever will change the experience when that motor restarts. The sound and rumble you hear is from the engine (go outside and listen). It's not from the exhaust.