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View Full Version : Vibration, Idle and mounts



Simonhla
09-27-2008, 05:28 PM
So I have rebuilt the engine. Replaced all the mounts, replaced a whole bunch of other miscellaneous parts and yet the car is still vibrating too much and from time to time really loud. It's annoying.

Ok so. When the car sits at idle it hovers at either 1100 rpms or 800. It seems to spend 80% of the time steady(ish) at 800 and the other 20% at 1100. The thing is, when it idles at 1100, the car is quieter and smoother, when it drops to 800, there is a deep vibration that seems to come through the bottom of the car and into the steering wheel. This is not as bad as before I changed all the mounts (including transmission mount). I also had the cradle spaced from the frame a little to reduce vibration further. And yet it still vibrates at idle. Annoying. The loud noise, sort of humming of the engine is another.

I did remove the silencer airbox from the wheel well because I appreciated the throatier noise it makes under acceleration but i am wondering if this causes increased noise the rest of the time. Am I just expecting too much from a car that is 16 years old? Or am I right to think that it should be really quiet in the cabin.

I am thinking of doing the whole 'frost king' or 'quiet walk' lining under the carpets etc to reduce noise but I don't want to do this just to mask a problem, if indeed I have a problem,and this of course will do diddly squat for any vibration. Thoughts?

Ryan
09-27-2008, 10:14 PM
do you have poly mounts?

Simonhla
09-27-2008, 11:35 PM
Got to be honest I do not know.
I had them replaced when the rebuilt was done but the car was still vibrating. I took it to another mechanic (someone I trust) who told me that there were two types of mounts for this car. The cheap ones from Korea and the good ones from Japan. I had the cheap ones. I opted to pay a little extra and have them replaced with the "good ones".......

Ryan
09-28-2008, 12:10 AM
Could be that the mounts are polyurethane or stiffer... mine are the poly ones from kirkosaurus and my car vibrates like crazy...

hobbie2k
09-28-2008, 04:45 PM
If the mounts are too stiff, it will vibrate a lot more, particularly is your idle quality isn't great. Are you sure it's the mounts, and not the engine itself? I don't know what you consider "loud" or what you consider excessive vibration to be...

Simonhla
09-28-2008, 10:41 PM
No i am not sure it is the mounts.
It most likely is the engine. But what could be causing it?
The vibration and noise isn't too bad to be honest but I did expect it to be smoother after everything I did.
At 1100 rpms it is smoother and quiet but when it drops to 800rpms I can feel the vibration coming through the seat and the steering wheel. You can see the wing mirrors vibrating slightly. It's annoying...is this normal?

brak
09-29-2008, 03:32 AM
my last celica did the same thing, it would drop to 800rpm, and then shudder as the engine struggled to stay running (to put it in simple terms). i always attributed it to the idle being too low and never really worried about it, because it didn't happen too often.

Not sure what the idle speed should be, but you should check the timing. if it's a little off, the engine will not run as smoothly as it should. :)

ciento44
09-29-2008, 11:50 AM
You're describing typical 5s behavior. :)

Galcobar
09-29-2008, 10:07 PM
Idle speed on a 5SFE is 700 +/-50 (for US) and 750 +/-50 for Canada.

I find my engine transmits vibrations through my car (to the point the hood shakes) between 600 and 800 RPM. Above or below that the vibrations are almost unnoticeable.

Simonhla
09-29-2008, 11:00 PM
Thanks guys. I guess I will have to learn to live with it then! Even though the idle is higher than spec when sitting at 1100rpms I actually prefer it because it is so smooth. C'est la vie.