924Board.org

MrJoshua · Joined: 19 Jul 2008 Posts: 13 Location: MARLBOROUGH,MA

it seems i have developed an engine vibration above 2500 rpm, doesnt effect power, or speed. its just annoying. any ideas what might cause this?
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MrJoshua
77 porsche 924
79 porsche 924

Vince Ponz · Joined: 02 Nov 2002 Posts: 3581 Location: Florida

Motor mount?
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"Never let them see you sweat"
77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock

Vince Ponz · Joined: 02 Nov 2002 Posts: 3581 Location: Florida

Motor mount?
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"Never let them see you sweat"
77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock

Smoothie · Posted: Sat Aug 02, 2008 4:06 am Post subject:

Motor mount?
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

MrJoshua · Joined: 19 Jul 2008 Posts: 13 Location: MARLBOROUGH,MA

if the motor mount was gone would i have excessive engine movement during acceleration? the air cleaner doesnt move much, ( i can see it under the cowl induction)
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MrJoshua
77 porsche 924
79 porsche 924

bass gt · Posted: Sat Aug 02, 2008 4:22 am Post subject:

Not nescessarily. The exhaust side mount has a spring inside that fails. But you can't tell by looking at it. You need to pull it out, and then you can see the failure.
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Front Wheel Drive is the Devil's work.

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Could be mixture as well. . .I just reduced an annoying vibration by richening up the mix a touch.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Does your steering wheel vibrate at idle? If so, motor mounts.
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1987 951 - M193 Version for Japan

Smoothie · Posted: Sat Aug 02, 2008 5:54 am Post subject:

Doesn't the 924NA have a little shock absorber ("torque strut") on the exhaust side of the engine? If yours is missing or worn out, may be time to install a new one (but not a new one from Porsche ($$$$$$$$)). They're available on eBay, and I think one or more on the board here have installed them. (-But of course make sure both motor mounts are good first.)

[ http://www.924board.org/viewtopic.php?t=23270 ]
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

There is such a device. From my limited experimenting, it is about as usefull as tits on a bull.
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1987 951 - M193 Version for Japan

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Mmmm, tits on a bull. . .
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

MrJoshua · Joined: 19 Jul 2008 Posts: 13 Location: MARLBOROUGH,MA

engine mount, sounds viable. no vibration at idle anywere though. plus the car runs fairly rich. good place to start. thank you.
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MrJoshua
77 porsche 924
79 porsche 924

elitejaso · Joined: 24 Jul 2007 Posts: 143 Location: Melbourne

+1 for stuffed engine mount, My car didnt vibrate on idle either only on accelertaion and the it was moving all over the place.
Was a stuffed drivers side engine mount (for u guys passeneger side) most common i think
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1981 924 turbo (daily driver)

poorsha924 · Joined: 13 Nov 2007 Posts: 143 Location: Kansas City Mo

Hi ther
I don,t belive this to be a motor mount concern

. That would be more noticable @ idle. Could be a worn torque tube support bearing slightly, out or driveshaftor worn out pilot bearing. Fisrt thing go to a small engine repair shop & buy a small engine tachometer (syrometer) Briggs& straton makes them about $25.00 You wll have to have another person helps you . Get the veschile up to where it vibrates ajust the syrometer wire to where it is not moving or as close as you can, should be real close to the RPM on the gauge look at the gauge it will tell you the Hz of the vibration. Depending on the the HZ you can isolate your concern.20 to 60 HZ is drive line or engine 80 to 100 HZ above 150Hz possible tire or wheel. Let me know your finding We Have a EVA at work that I can aceess to tell you what to look for once you can tell me the Hz reading Hope this helps

Poorsha 924
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79 924S snailshell
audi big bore t-body
16" turbo wheels

Vince Ponz · Joined: 02 Nov 2002 Posts: 3581 Location: Florida

I had the drivers side [US] mount fail coming home from Pocono Raceway a couple of years ago. Under power it ran well but at idle it sounded as if the valves we being eaten by the pistons.

Broken mount.

Of course there could be other problems. Most of which will be covered by all the rest of the guys.
_________________
"Never let them see you sweat"
77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock