jumerle

Hello Lexus lovers,
I am getting a vibration at 1800 rpm on my 1998 LS40O. Could anyone say what might be the cause of this?
I've changed engine mounts and transmission mount about 8 days ago.
Your input will be greatly appreciated. Thank you.

Losiracer2

It's the aftermarket mounts you used, hate to say I told you so.

YODAONE

A picture is worth a thousand words...

Suggest you remove, repackage and return mounts to whomever you purchased and cancel credit card charge.

Then visit Toyota or Lexus for motor mounts.

Yamae

The revolution 1800rpm means 30 revolutions per second. In another word it is 30Hz and is the first resonant frequency of the power train. The OEM mounts for the power train are designed to eliminate the resonance. Non OEM mounts are probably not designed so. "Penny-wise and pound-foolish" is always true for critical parts.

Moarpower

How severe? Even after market mounts would not create severe and concerning vibration, they are just not as smooth feeling as the oem ones. Mine has aftermarket mounts from previous owner and i get no vibration that raises concern.

Yamae

You can compare with this.

Moarpower

Of course Yamae. I have driven ls400s with oem mounts that are super smooth. However the OP is complaining about vibration. The aftermarket mounts should not cause excess vibration, they are just not as efficient at dampening the engine vibration. They just feel like every other car, versus the super smooth OEM mounts.
I am trying to clarify if there is a concerning vibration or just a little more than OEM.

sha4000

iTrader: (1)

The aftermarket mounts I tried a couple of years ago made the WHOLE engine vibrate at idle. I turned the car off and immediately took them off. Not saying that's the OPs problem but if it was not there before the change then it's a good suspect.

jumerle

My Lexus specialist mechanic/technician almost did not feel the vibration. He drove it at low and high speed then told me that he cannot feel what I am feeling. So I put the vehicle in park and slowly accelerated until it got to 1800 rpm. As I held it steadily there, he immediately felt it. There is no significant vibration above 2000 rpm but I have become so used to my smooth ride that I still feel a very slight vibration.

jumerle

Losiracer2, I will confirm whether you are correct when I replace the mounts with genuine Lexus/Toyota mount. I have already requested a refund which was accepted by the seller and I will be receiving my genuine mounts ($199.95) on Friday. So by Sunday night I should post a report about the performance.
Watch this space Losiracer2. I hope you are right because it is all because of your posts that I made the decision to go genuine.
I hope for your reputation I would be thanking you rather than criticizing you next Monday....Lol.

jumerle

Tamae, let's hope that you and Losiracer2 are correct about this vibration. Do remember that it is insignificant but because I am used to my smooth ride, I can easily detect the slightest vibration on my vehicle.
I love my 1998 LS400. I fitted the PIONEER AVIC 8100 unit, so I have so many features to play with including DVD player, GPS, Android Auto. Android Auto is really a blessing. With Android Auto I do not have to touch my phone to make and receive call and send and receive texts. All I have to say is: "OK Google, send text to John," and it asks me for the message. I say the message and it repeats it and asks whether I wish to send. The same for text messages coming in.....it reads my message clearly for me. I can also play music on my phone, ipad or tablet through my car speakers. I can be listening to music as I drive while my rear seat passengers watch a movie on the two monitors I connected to my Pioneer unit. I can play music from a USB flash drive and an SD card. The only feature I miss the use of on my factory radio is the cassette player. I have some really good back-in-time music on my cassettes that I would love to transfer on a flash drive, SD card or CD.
I also installed a back up camera connected to the Pioneer unit and finally I installed backup sensors with the beeps that allows me to determine how close I am to an object behind me.
I will be installing a front camera which I have already purchased but I might need a switch to turn it on and off. That might be a difficult task for me so I am looking for some assistance with that project. Any takers?

jumerle

Losiracer2, you were correct. My mechanic just finished replacing the aftermarket mounts with the genuine Lexus mounts and the result is this: a softer ride but there is still a slight vibration at 1800 rpm. I can live with it but I don't think I will do so forever.
The good news is my mechanic wants to buy the car from me so that says something.

Moarpower

If the vibration is still there, the oem mounts only help reduce it, not fix the issue. Clearly something else is up

Losiracer2

I'm glad the mounts helped. I too was considering using cheap mounts when I first looked at the price difference, but then I looked into what this car was built upon, its refinement and NVH isolation and I knew I couldn't sacrifice that for an extra $100, so I opted for OEM Lexus.

At this point, I would look into possibly the harmonic balancer? I have read in certain people's cases where the rubber would come separated from the metal part of the pulley and would vibrate or wobble. But yours is either bad and failing or its still holding on. Its hard to say because it has to do it only at certain RPM, so I'm thinking that's the only other rotational part of the engine where it would cancel out vibrations. That has to be something to consider since our cars are over 20 years old, in my 97' model's case. Luckily mine is still good, or might have been replaced I'm unsure of the complete history of my car.

If you're getting a vibration when the car is moving at 1800 rpm, then it could possibly be a bushing housed in one of the control arms that has torn or deteriorated to the point of becoming sloppy. My front left LCA bushing was completely torn causing a clunking and a noticeable vibration when at highway speeds. At this point you can't really rule things out since our cars are aging, and nothing rubber lasts forever.

jumerle

Losiracer2, I replaced the aftermarket engine mounts with the genuine Toyota/Lexus mounts and I am still getting the vibration. It is a very slight vibration that I feel on my seat while driving at all speeds. I also feel it while in park but it is more pronounced at 1800 rpm.
What could be the cause.of this vibration? Note that engine mounts and transmission mount were replaced.