Shaking When Idling
02-21-12, 06:50 PM
#46
Moderator
I did clean my throttle body and mass air flow sensor when the mounts were replaced, so it could have been a combination of all three. Whichever, it did make a difference for me and there was nothing Wizardly about it. LOL. Especially the clearing part...the dealer wanted ridiculous money for ½ hours work...so I did it myself.
03-08-12, 11:54 AM
#47
Driver School Candidate
Join Date: May 2010
Location: ca
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Have this exact same problem. Slight vibe at idle in park, more or less the same in gear. But more than before. Wife owned the car since new, I've been driving since 25k miles 
. 78k mi on a 2002.
Going in this week for the 120k service and new plugs. Curious to see if that makes a difference, and what they say about the motor mounts.
. 78k mi on a 2002.Going in this week for the 120k service and new plugs. Curious to see if that makes a difference, and what they say about the motor mounts.
Vibration was not that noticeable so I'm a little suprised they were that bad, but it all makes sense. Just fyi, don't wait for giant clunks to inspect motor mounts.
One surprise - after that repair and a full 120k service, I've picked up close to 1 mpg compared to my commuting avg over the last several years.
03-09-12, 02:57 AM
#49
Intermediate
03-10-12, 04:59 PM
#50
Instructor
Thread Starter
latrain, thanks for following up. I also recently found the vapor return line disconnected, I simply reconnected it and didn't look for the root cause. But now that I think about it, the root cause of the vapor line getting disonnected could be the bad motor mounts, which I have been postponinig for a while.
Was the $700 bill at the dealer, or elsewhere?
Was the $700 bill at the dealer, or elsewhere?
03-10-12, 07:24 PM
#51
Old school, we would simply open the hood, HOLD THE BRAKE DOWN FIRMLY, put the car in drive and goose the engine. If the mount is good it won't lift. If bad the engine will jump. Put it in reverse to test the other engine mount. If any are bad then replace them all including the tranny mount because it's cheap. Well it was cheap before Lexus.
Last edited by Bon; 03-11-12 at 08:16 AM. Reason: Clarification
03-10-12, 10:07 PM
#52
Old school, we would simply open the hood, put the car in drive and goose the engine. If the mount is good it won't lift. If bad the engine will jump. Put it in reverse to test the other engine mount. If any are bad then replace them all including the tranny mount because it's cheap. Well it was cheap before Lexus.
I'm also having this slight shaking when in drive when the a/c is not on. I did have the dealer checked the vibration last January, 12 and they said they coudln't duplicate the problem,
Now my Lexus platinum extended warranty just expired on March 4, 2012. And today I noticed the shaking was pretty bad. I wonder the extended warranty covers this preexist problem ? or I have to pay for the repair? Thank for any input?
03-11-12, 08:14 AM
#53
Put the car in drive. Hold the brake pedal down very, very firmly. Push the gas pedal briefly (goose it). This applies significant engine torque to the drive train and the only thing holding the engine from rotating are the engine mounts. One is being lifted and the other compressed. When in reverse the opposite torque is applied to the engine and so the opposite engine mount will try to lift.
I haven't done this in my SC. In other cars we could see the engine in the gap between the hood and the windshield wipers. Some engine mounts have steel built into them that limits the excursion of the engine after the rubber fails - others don't. You can still see the engine rise in either case but it's less dramatic if there are the steel limiters inside the mounts.
(I edited my previous post for clarity. And furthermore, please don't drive through your garage wall if you're trying this and don't let anyone stand in front or behind your car. I'm not a lawyer and don't want to have to hire one!)
I haven't done this in my SC. In other cars we could see the engine in the gap between the hood and the windshield wipers. Some engine mounts have steel built into them that limits the excursion of the engine after the rubber fails - others don't. You can still see the engine rise in either case but it's less dramatic if there are the steel limiters inside the mounts.
(I edited my previous post for clarity. And furthermore, please don't drive through your garage wall if you're trying this and don't let anyone stand in front or behind your car. I'm not a lawyer and don't want to have to hire one!)
Last edited by Bon; 03-11-12 at 08:29 AM.
03-12-12, 12:44 AM
#54
well, I tried it.
I found when I put in reverse the engine had moved up a lot; then when in drive, the engine still moved up but not as much; then I tried with my 99 GS400 which I had my engine mounts replaced a year ago; GS400 engine did not move at all. So I'm sure my SC engine mounts are bad! I'll call the dealer to have it fixed tomorrow. Thank you for your suggestion. Really appreciated
I found when I put in reverse the engine had moved up a lot; then when in drive, the engine still moved up but not as much; then I tried with my 99 GS400 which I had my engine mounts replaced a year ago; GS400 engine did not move at all. So I'm sure my SC engine mounts are bad! I'll call the dealer to have it fixed tomorrow. Thank you for your suggestion. Really appreciated
03-12-12, 11:14 AM
#56
what i did was to have the hood opened so that I could see the engine (**remove plastic engine cover so you could see the upper intake manifold**) while sitting inside the car. With the engine running while stepping on brake firmly (I did not step on gas), when I shifted from P to Reverse, I could see the engine jumped up quite a bit ; then I shifted from P to D, I also saw the engine jumped up too. My GS400 engine didn't move at all with the same procedure.
Last edited by lexie; 03-12-12 at 05:57 PM.
03-12-12, 03:00 PM
#58
Today is the first time I've looked at this thread.. But boy am I glad I did. I did the open hood procedure, and found out that the clunking I hear when I accelerate is indeed the engine popping up. Thank you all for your input to help find this! I have been freaking out about that clunk for months now.
03-12-12, 05:49 PM
#59
Today is the first time I've looked at this thread.. But boy am I glad I did. I did the open hood procedure, and found out that the clunking I hear when I accelerate is indeed the engine popping up. Thank you all for your input to help find this! I have been freaking out about that clunk for months now.
03-12-12, 08:21 PM
#60
It may also help you with some of those rattles you've mentioned in other threads. The engine and transmission and their associated mounts create a triangle of chassis support that resists twisting. With a broken mount(s) you could very well have the chassis moving around on you and letting the roof rattle around.