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Just thinking out loud
Join Date: Nov 2001
Location: Close by
Posts: 6,885
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Vibration
An engine vibration graced me today on a trip. At 2500 rpm it cycles about every second, pulsating consistantly. It cycles quicker as rpms increase. At idle nothing seems wrong, it isn't present at 1500-2k ish rpm. What baffles me is that I was driving along, 90 miles into a 200 mile trip, and the vibration arose out of no where. I thought the balance shaft belt may have skipped a tooth or went all together, I didn't have tools to check, and call me crazy, or stupid, or both, I went on. I made it home, nothing changed for the worse or better.
I don't have much time to tinker with it today but I would like some ideas, thoughts or suggestions, outside of don't run it anymore till.....Thanks, Matt.
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83 944 91 FJ80 84 Ram Charger (now gone) |
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09-19-2005, 10:08 AM
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Cars & Coffee Killer
Join Date: Sep 2004
Location: State of Failure
Posts: 32,246
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Could also be bad engine mounts.
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Some Porsches long ago...then a wankle... 5 liters of VVT fury now -Chris "There is freedom in risk, just as there is oppression in security." |
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09-19-2005, 10:27 AM
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Join Date: Jul 2005
Location: Pasadena, CA
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I think engine mounts almost always vibrate at idle. And they don't usually go all at once.
The idea of a the balance shaft belt slipping or breaking seems plausible to me. -Ian
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Stock 1988 951, TT aero wipers |
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09-19-2005, 06:01 PM
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Join Date: Apr 2005
Location: Ontario, Canada
Posts: 4,554
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mine just started doing the same thing.. funny you should say that...
doing about 120km on the highway, call me crazy.. but if i pay close attention to it, it's like i can feel the vibe start at the bottom of my feet, move up my legs and into my body.. it's almost as if the vibration travels.... and no, it's not the road.. it cycles every second or so like the OP said.......
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Kyle 2008 Mini Cooper // '83 Porsche 944 // '01 Mazda Protege [sold] // "Never break more than you fix!" - SoCal Driver |
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09-19-2005, 07:45 PM
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Join Date: Nov 2001
Location: Melbourne, Florida
Posts: 431
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Could also be the rubber centered clutch disk has deteriated and become imbalanced (missing chunks of rubber).
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1986 951 |
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09-20-2005, 07:57 AM
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I'm going with the balance shaft belt, I'll bet it either broke in half, or is so loose it skipped a tooth.
If so, better check it out, becaue that belt can potentially jump into another belt and cause some damage. regards, P
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1983 928S 5-speed, 1984 944, 1990 944S2 Cabriolet My other car is a Chris Craft Commander http://www.chriscraftcommander.com |
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09-20-2005, 08:12 AM
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Just thinking out loud
Join Date: Nov 2001
Location: Close by
Posts: 6,885
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It does this when stopped as well as moving in any gear. The clutch has been replaced with a spring centered unit. I'll check the balance belt asap. Thanks everyone.
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83 944 91 FJ80 84 Ram Charger (now gone) |
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09-20-2005, 01:42 PM
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Location: Connecticut
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I wouldn't run the car until you can check it.
Park it where you want to work on it. Let it sit overnight, so the engine is stone-cold in the morning (optimal temp for adjusting belts). |
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09-20-2005, 01:44 PM
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Just thinking out loud
Join Date: Nov 2001
Location: Close by
Posts: 6,885
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Balance belt it was. Sheared the teeth on one side, and was about to break free. Eldorado, I'll be willing to bet you have the same problem. FYI, these belts have no more than 5K, H2O while you are in there too. Check your belts, I got really lucky.
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83 944 91 FJ80 84 Ram Charger (now gone) |
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09-23-2005, 06:59 AM
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