What causes engine vibration?

fatoeknee · February 26th, 2009, 11:06 AM

Guys, at low RPM my engine vibrates moderately and it seems like it stops after I get above 2100 RPM or so ...I checked my plugs and they all looked ok. Looked at the motor mounts and they checked out fine too - on top of that I have no CEL so I'm pretty much stumped. I'm workin on a 5.0 fuel injected 1968 coupe that I just got runnin...

Any input or ideas would be great
Thanks a bunch
Tony

95StangMX · February 26th, 2009, 01:01 PM

is the motor stock? Was it running ok and just started doing this?

93hatch · February 26th, 2009, 01:05 PM

Originally Posted by fatoeknee

Guys, at low RPM my engine vibrates moderately and it seems like it stops after I get above 2100 RPM or so ...I checked my plugs and they all looked ok. Looked at the motor mounts and they checked out fine too - on top of that I have no CEL so I'm pretty much stumped. I'm workin on a 5.0 fuel injected 1968 coupe that I just got runnin...

Any input or ideas would be great
Thanks a bunch
Tony

my cars EXACTLY the same, i think mine is the harmonic balancer cuz i can see some of the rubber like coming out of it

95StangMX · February 26th, 2009, 01:11 PM

+1 or if its a rebuilt motor with a new rotating assembly that was balanced poorly

fatoeknee · February 26th, 2009, 01:39 PM

I actually thought it could be a balance issue ...motor has been sitting for some time (probably 4 plus years) ...I'm trying so hard to remember but I think the balancer I bought for it was a new 50 oz replacement along with the flex plate for the c4 being a 50 oz replacement as well - never got them balanced to the motor though. Can a balancer go bad just sitting? LOL - i had to scrape a ton of rust off it just so I could see the timing marks to set timing.

91cobra5.0 · February 26th, 2009, 01:56 PM

i dont think that the balancer could go back but think of all those chmicals building or eating at the block or crank or werever, if it sat for 4 plus years u may have to rebuild it, did u do compression checks to get a idea of the shape the cylenders are in?

89LX347 · February 26th, 2009, 03:11 PM

a stuck lifter

fatoeknee · March 2nd, 2009, 03:07 PM

Did a compression check ...all cylinders are within 130-150 suprisingly - any other ideas guys?

BUGMAN · March 3rd, 2009, 11:31 PM

If the motor is 28oz balance then it will do the same thing even with a 50oz balancer and flex plate/fly wheel. What year is the motor and if it was rebuilt what was the build balanced at? I have 28, 50 and 0 balanced 302 EFI's and carb'd and if they aren't matched you will get the same thing.

TKOTLARZ · March 4th, 2009, 12:04 AM

wat about ur u-joints? easy check

chickenbot · March 4th, 2009, 12:19 AM

Originally Posted by 93hatch

my cars EXACTLY the same, i think mine is the harmonic balancer cuz i can see some of the rubber like coming out of it

ya its time to change yours.. get a sealed one

fatoeknee · March 4th, 2009, 01:31 AM

Engine is a 1991 ...Today I noticed a little condensation coming out of my tailpipes on and off and now I'm wondering if that has anything to do with it - the little puffs of smoke that come out are just slightly white but don't smell like antifreeze. Makes me angry I should have bought everything new but I tried to cut corners and bought all used parts

chickenbot · March 4th, 2009, 04:27 AM

are you letting it warm up? it could just be condensation from when you parked it.. drive it around for a lil while and does it still do it?

fatoeknee · March 4th, 2009, 09:57 AM

Still does it after it's warm

chickenbot · March 4th, 2009, 10:23 AM

do you smell maple syrup?

Squints · March 4th, 2009, 10:47 AM

1:31 AM

Originally Posted by fatoeknee

Engine is a 1991 ...Today I noticed a little condensation coming out of my tailpipes on and off and now I'm wondering if that has anything to do with it - the little puffs of smoke that come out are just slightly white but don't smell like antifreeze. Makes me angry I should have bought everything new but I tried to cut corners and bought all used parts

10:23 AM

Originally Posted by chickenbot

do you smell maple syrup?

chickenbot · March 4th, 2009, 10:59 AM

shhh.. maybe he doesnt know that hot antifreeze smells like maple syrup lol

M L Struck · March 4th, 2009, 11:03 AM

Originally Posted by BUGMAN

If the motor is 28oz balance then it will do the same thing even with a 50oz balancer and flex plate/fly wheel. What year is the motor and if it was rebuilt what was the build balanced at? I have 28, 50 and 0 balanced 302 EFI's and carb'd and if they aren't matched you will get the same thing.

+1

check out the rubber in your balancer

chriswao · March 4th, 2009, 12:31 PM

vaccume leak?

February 26th, 2009, 11:06 AM	#1
fatoeknee Regular 2002 Mustang GT Haven't run it Join Date: Jan 2009 Location: Houston Posts: 92 iTrader: 0 reviews	What causes engine vibration? Guys, at low RPM my engine vibrates moderately and it seems like it stops after I get above 2100 RPM or so ...I checked my plugs and they all looked ok. Looked at the motor mounts and they checked out fine too - on top of that I have no CEL so I'm pretty much stumped. I'm workin on a 5.0 fuel injected 1968 coupe that I just got runnin... Any input or ideas would be great Thanks a bunch Tony Last edited by fatoeknee; February 26th, 2009 at 11:08 AM.

February 26th, 2009, 01:01 PM	#2
95StangMX MM Fanatic 95 Mustang GT depends how many people are pushing Join Date: Oct 2007 Location: Playa del Carmen, Mexico Posts: 3,243 iTrader: 0 reviews	is the motor stock? Was it running ok and just started doing this? __________________ People should think about boarding up their glass house before starting a rock fight!

February 26th, 2009, 01:11 PM	#4
95StangMX MM Fanatic 95 Mustang GT depends how many people are pushing Join Date: Oct 2007 Location: Playa del Carmen, Mexico Posts: 3,243 iTrader: 0 reviews	+1 or if its a rebuilt motor with a new rotating assembly that was balanced poorly __________________ People should think about boarding up their glass house before starting a rock fight!

February 26th, 2009, 03:11 PM	#7
89LX347 Hardcore Enthusiast Join Date: Apr 2007 Posts: 1,304 iTrader: 0 reviews	a stuck lifter __________________ I believe in art when it is not seen. I believe in music when it is not audible. I believe in God when He is silent.

March 3rd, 2009, 11:31 PM	#9
BUGMAN Regular Join Date: May 2008 Location: TRAILER PARK Posts: 157 iTrader: 0 reviews	If the motor is 28oz balance then it will do the same thing even with a 50oz balancer and flex plate/fly wheel. What year is the motor and if it was rebuilt what was the build balanced at? I have 28, 50 and 0 balanced 302 EFI's and carb'd and if they aren't matched you will get the same thing. __________________ You haven't failed until you stop trying.

February 26th, 2009, 01:39 PM	#5
fatoeknee Regular 2002 Mustang GT Haven't run it Join Date: Jan 2009 Location: Houston Posts: 92 iTrader: 0 reviews	I actually thought it could be a balance issue ...motor has been sitting for some time (probably 4 plus years) ...I'm trying so hard to remember but I think the balancer I bought for it was a new 50 oz replacement along with the flex plate for the c4 being a 50 oz replacement as well - never got them balanced to the motor though. Can a balancer go bad just sitting? LOL - i had to scrape a ton of rust off it just so I could see the timing marks to set timing.

February 26th, 2009, 01:56 PM	#6
91cobra5.0 Hardcore Enthusiast 98 Cobra Join Date: Jan 2008 Location: Bay Area, Ca Posts: 2,057 iTrader: 0 reviews	i dont think that the balancer could go back but think of all those chmicals building or eating at the block or crank or werever, if it sat for 4 plus years u may have to rebuild it, did u do compression checks to get a idea of the shape the cylenders are in?

March 2nd, 2009, 03:07 PM	#8
fatoeknee Regular 2002 Mustang GT Haven't run it Join Date: Jan 2009 Location: Houston Posts: 92 iTrader: 0 reviews	Did a compression check ...all cylinders are within 130-150 suprisingly - any other ideas guys?

March 4th, 2009, 12:04 AM	#10
TKOTLARZ Hardcore Enthusiast 1994 GT Join Date: Nov 2007 Location: lake worth, Florida Posts: 1,002 iTrader: 0 reviews	wat about ur u-joints? easy check __________________ Cohagan Engineering, Inc.

March 4th, 2009, 01:31 AM	#12
fatoeknee Regular 2002 Mustang GT Haven't run it Join Date: Jan 2009 Location: Houston Posts: 92 iTrader: 0 reviews	Engine is a 1991 ...Today I noticed a little condensation coming out of my tailpipes on and off and now I'm wondering if that has anything to do with it - the little puffs of smoke that come out are just slightly white but don't smell like antifreeze. Makes me angry I should have bought everything new but I tried to cut corners and bought all used parts

March 4th, 2009, 04:27 AM	#13
chickenbot Enthusiast 1990 mustang gt eventually Join Date: Nov 2007 Location: plano, tx Posts: 938 iTrader: 0 reviews	are you letting it warm up? it could just be condensation from when you parked it.. drive it around for a lil while and does it still do it? __________________ 1990 gt 5.0 Mac Performance 76mm straight shot intake 70mm Accufab tb and egr spacer Trick Flow Track Heat u/l intake 3.55 gears MSD distributor, Blaster Coil, and 8.5mm wires

March 4th, 2009, 09:57 AM	#14
fatoeknee Regular 2002 Mustang GT Haven't run it Join Date: Jan 2009 Location: Houston Posts: 92 iTrader: 0 reviews	Still does it after it's warm

March 4th, 2009, 10:23 AM	#15
chickenbot Enthusiast 1990 mustang gt eventually Join Date: Nov 2007 Location: plano, tx Posts: 938 iTrader: 0 reviews	do you smell maple syrup? __________________ 1990 gt 5.0 Mac Performance 76mm straight shot intake 70mm Accufab tb and egr spacer Trick Flow Track Heat u/l intake 3.55 gears MSD distributor, Blaster Coil, and 8.5mm wires

March 4th, 2009, 10:59 AM	#17
chickenbot Enthusiast 1990 mustang gt eventually Join Date: Nov 2007 Location: plano, tx Posts: 938 iTrader: 0 reviews	shhh.. maybe he doesnt know that hot antifreeze smells like maple syrup lol __________________ 1990 gt 5.0 Mac Performance 76mm straight shot intake 70mm Accufab tb and egr spacer Trick Flow Track Heat u/l intake 3.55 gears MSD distributor, Blaster Coil, and 8.5mm wires

March 4th, 2009, 12:31 PM	#19
chriswao Regular 1989 mustang gt 8th 5.70 Join Date: Feb 2009 Location: savannah Posts: 197 iTrader: 0 reviews	vaccume leak?

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