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vibration at idle = cracked motor mount

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Old 06-20-2005, 07:10 AM
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i have this problem too. consulted my mech, he claim that by changing the mount will not solve the vibration. it might be due to other factors. changing the mount will cost ard 400. if it does not solve the prob its not money well spend. he recommend a full diagnose at 120. any comments?
Old 06-20-2005, 08:27 AM
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Originally Posted by coolvolka
i have this problem too. consulted my mech, he claim that by changing the mount will not solve the vibration. it might be due to other factors. changing the mount will cost ard 400. if it does not solve the prob its not money well spend. he recommend a full diagnose at 120. any comments?
If your idle vibration is severe, the tech is obligated to check the mount for damage. If the mount looks fine, then there's no reason to replace it. If it's cracked, warranty will cover replacement and it WILL improve your idle vibration. You should not pay for a full diagnosis at $120 until he at least visually inspects your mount!
Old 06-20-2005, 05:45 PM
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The engine mounts on the RX-8 are OIL filled so they act kind of like a hydraulic damper.If the rubber 'cracks' you will observe oil run out.I have not seen a leaking mount on an RX-8 yet but I have seen one on a Mazda3.Oil is very obvious,so if you don't see oil there is unlikely to be a problem with the mount.
Old 07-08-2005, 12:59 PM
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i've had the same vibrating issues. my car was in an accident so that probably contributed to damaged mounts. i brought it to the dealer and they replaced both left and right engine mounts under warranty and the vibration was gone. it actually felt like i was driving a brand new rx8 again. smoooooooooooth.
Old 07-08-2005, 09:18 PM
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The part numbers have changed again. Have the dealer call the tech line for the latest and greatest.
Old 07-08-2005, 09:30 PM
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I think the rough idle is only ok when your car is tuned with a Turbo or SC. I dont think its normal when your car is stock. Something is wrong with the idle from the re-flash program. My 8 never had this rough idle untill I got flashed like over 10 times.
Old 07-11-2005, 02:59 PM
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My car has had a rough idle since new, but is worse since the latest flash in June. I commented on it when I picked up the car, but the mechanic had no explanation. I checked the motor mount last night, and it looks fine. I'm going to call the dealer to see if they have another idea. The latest flash is great except for the idle. The soot in the exhaust pipes is almost gone, more power, gas mileage has improved about 1 mpg. If they straighten out the vibration at idle, the car will be fantastic.
Old 07-11-2005, 08:01 PM
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I had the problem with my car vibrating way too much at idle. I have an automatic, not manual. I took it in for service today and they fixed it up with no problem. They replaced the motor mounts and the receipt said that the old ones were "distorted". I was glad they had the parts in stock so I didn't have to wait for them.
Old 07-15-2005, 03:35 PM
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Originally Posted by srm858
.. If they straighten out the vibration at idle, the car will be fantastic.
When I first got my car (July '03) I had absolutely NO vibration - since all these flashes the shifter always has some vibration and will rock 'n roll some at a red light!
Bugs the heck outta me.
Old 07-15-2005, 06:29 PM
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I think we're talking about the whole car, nut just the shift ****, which is normal.
Old 07-15-2005, 07:50 PM
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Yea dont let the lill' shifter get to ya
Old 07-16-2005, 02:20 AM
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My car also has that problem? so what do i tell the dealer? do i say Yea its doing this fix it or something? their probably just going to say its normal and not check it out, my dealer is an ***
Old 10-23-2005, 12:41 AM
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I had same problem, and they replaced the mount but problem still persists.

I took it in again, and they said that was normal (then I made them sit in it with me, and they confirmed that there was a vibration. It took me 15 seconds to get them notice it and they had the car for hours!!!)

Next time I took it in, they said the motor mount is fine and it was my gas!!!! What??!? They asked me if I was using lower octane gas and I told them I always used premium (93) and they said they experienced similar problem and fixed it by putting chevron 93 gas!
I don't think whole engine would shake because of bad gas! B**lSh*t!

If I can't get this problem fixed in next couple of months (I don't have time to spend all my time in the dealership), I am trading mine in, not because I hate the car but because of MAZDA's inability to service RX-8 properly. I will call this a failed experiment if I do say good bye.
Old 10-23-2005, 01:54 AM
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Originally Posted by typej

Next time I took it in, they said the motor mount is fine and it was my gas!!!! What??!? They asked me if I was using lower octane gas and I told them I always used premium (93) and they said they experienced similar problem and fixed it by putting chevron 93 gas!
I don't think whole engine would shake because of bad gas! B**lSh*t!
I remember reading one of the posts that said lower octane gas caused vibration/rough idle. So there might be some truth to it.

My car vibrates too. And I use 91 all the time. So, I guess there is definitely more than one reason....

I will bring my car to the dealer and see what they have to say, but won't hold my breath on them fixing it.
Old 10-23-2005, 07:47 PM
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Originally Posted by fray
Just an FYI, I inspected the motor mounts on my 8 (17k miles, 05/03 build date). There are three yellow dots on it.. but as far as I can tell no cracks.

I have pictures of the mount if anyone cares.

So speaking of the cracks where are they present? At the weld of the two support posts and the metal ring?
I know this is an old post but, the 3 yellow dots means that your Mazda dealer mechanic has inspected your mount on more than one occasion...they are doing their job correctly..
Whenever there is a mechanical inspection on an external mechanical part required by Mazda Japan a "good" dealer will always mark it with a yellow dot to visually prove the job is done.

As we know the engine mounts have been modified a few times by the factory, they wont be doing a recall as such, but repair at service schedule for owners who complain of excessive vibration.

As a suggestion to satisfy your mind and to know what mount is in your car and the Part Number, get friendly with your Mazda Parts Guy, they can look up exactly what part(s) are fitted to your 8 at production and give you the part number(s). Don't rely on the info from mechanics or even Service Managers, the parts guys know more on what parts are installed on your 8 before any TSB is issued.
Take your model chassis number into the Parts Department with you.
Remember to ask the parts guy for the part number that was installed on YOUR CAR at production, then ask has it been modified since.

You can then talk to your techs and if required get the new (modified) parts installed., or, at least you will know that you have the lastest parts already in your RX-8.

A modified Mazda part will always have a slight change to the part number at the end..ie -39-040, then -39-040A, then -39-040C, the "C" is the latest part.

Last edited by ASH8; 10-23-2005 at 08:05 PM.
Old 11-18-2005, 01:25 AM
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Does anyone have a cracked motor mount they don't want? I would like to tear it apart and fill with some 90A durometer urethane that I have left over.
Old 11-18-2005, 03:59 PM
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The vibration problem is a result of the car running to lean at idle. I know because I've run the car off of a standalone for fuel only and I can make the problem go away if I richen the afr up at idle. I think the injectors struggle to keep it lean at idle and their constant dance of cycling on and off is what causes the idle to be rough. The negative timing might also contribute, I'm not sure since I haven't messed with that yet.

Why it gets worse with the A/C on I'm not sure.
Old 11-19-2005, 03:59 AM
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Originally Posted by brillo
The vibration problem is a result of the car running to lean at idle. I know because I've run the car off of a standalone for fuel only and I can make the problem go away if I richen the afr up at idle. I think the injectors struggle to keep it lean at idle and their constant dance of cycling on and off is what causes the idle to be rough. The negative timing might also contribute, I'm not sure since I haven't messed with that yet.

Why it gets worse with the A/C on I'm not sure.
Quite obvious, if you get a richer mixture, it reduces cycle-by-cycle combustion variations. You'll get the same improvement if you increase idle speed, or load. The fact is, the engine must run at lambda = 1 in idle condition for emission purposes.

The best solution would be, in my opinion, to increase idle speed by 100 - 150 rpm.

Fabrice
Old 12-07-2005, 05:20 PM
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I have about 18K miles on my Auto RX-8, everytime I stop at a light, the car shakes like no other and it is probably the most annoying thing thats happened to my RX-8, what should i tell the dealership so they can fix this, someone please help me, and if there is any way you can email me at Ryan.Q@godirectlending.com with the information, thanks a lot.
Old 12-08-2005, 04:09 AM
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I'm fed up with it too. I'm now working on an auxiliary electronic device (yes, yet another "box") that will enable to raise the idle speed and therefore making it more stable. No need to reprogram the PCM (nobody can for the moment anyway), it wil connect to 3 wires from the engine loom, plus 12V and ground.
Will work on any ECU controlled gasoline engine.

Fabrice
Old 12-09-2005, 02:14 PM
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Originally Posted by Flawless
I had the problem with my car vibrating way too much at idle. I have an automatic, not manual. I took it in for service today and they fixed it up with no problem. They replaced the motor mounts and the receipt said that the old ones were "distorted". I was glad they had the parts in stock so I didn't have to wait for them.
NOW that's how a GOOD dealer should operate...hassle free for the owner/customer..they have a good experience.

I am being presumptuous here, but, at a guess this dealer "services" their clients the way they should, they probably have an adequate spare parts store with switched on staff/good inventory, and a service department that gets the job done.

ie. parts in stock and the job is done with little fuss, and because the parts were there the customer did not have to come back..
which is a cost saving for the customer and the dealer., not to mention the great word of mouth advertising by the owner.

As an ex Mazda parts and fixed operations manager this experience is what all dealers should strive for....sorry for being a little self indulgent here...its the Mazda blood in me.
Old 05-06-2006, 11:09 AM
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Originally Posted by snap-on
The parts system shows the mounts have been modified 3 times.

F151-39-040C (HP)
F151-39-050C (SP)

The latest mount should have a heat shield to protect the rubber from the exhaust heat.
Looking at the parts designations, this does not look like a revised mount, but just the second shoe dropping. (HP) would be the mount for the high power engine, (SP) for standard power.
Mitch (owner of a standard power (auto) that has the rattle at idle symptoms. My dealer found nothing when I brought it up before; now, thanks to you guys, I can make him take me seriously.
Mitch
Old 05-06-2006, 08:10 PM
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checked my car today,

when i started my car. it does not have any vibration. but when i am driving, after i drive over 15 minutes and idle. the small vibration came out. when i stop on traffice lights.

is this normal for Type E, 4AT?
Old 07-18-2006, 09:51 AM
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what is the octane level of Shell super (RED), and shell unleaded (green)?
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