engine vibration? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mooneyes · 08-17-2003, 08:31 PM

.....got a vibration so i unbolted my torque converter to make sure it wasn't the tranny and now its 3 times as bad...i guess the converter was dampning the vibration...everybody i talk to said the only time they saw this was with a broken crank!!!!...damn i dont know how i would have done that...going to try to get it out this week and tear it down...anybody ever have this prob.?

**old Rusty C10** · 08-17-2003, 08:57 PM

any time ive had a broken crank the motor wouldnt work at all

**68 Stepside** · 08-17-2003, 09:00 PM

how about a bad/slipped harmonic balancer?

*Randy70C-10* · 08-17-2003, 09:00 PM

I don't know, but if you want to upgrade I have a 350, 260 horse engine with less than 2,000 mile on a complete rebuild. I swapped a ZZ-3 in it's place so now I have a spare engine. Another board member was asking about it but I haven't heard from him lately. Oh.......$900.

weasel29gm · 08-17-2003, 11:35 PM

Check all your mounts motor and tranny. A buddy had the same thing and turned out to be the tranny mount.

cb · 08-18-2003, 08:25 PM

If it is vibrating a lot, check the fan. You loose one blade and it shakes real bad. It is not a broken crank.

Gordo · 08-18-2003, 08:43 PM

I remember running a big block 460 cu in F*rd that had a broken crankshaft and there was a SERIOUS noise that went with the vibration. Took it apart later and it was infact broken in two between the first and second main bearings. I really doubt that is your case. Is it possible a couple of plug wires got mixed up or maybe moisture under the dist cap? Have you done any work on it lately or made any changes?

CoryM · 08-18-2003, 09:08 PM

Ive seen a ferd break a crank and it still ran with no noises. However the crank pulley was moving in and out about 1/2". Make sure its not just having ignition troubles. With a bad mount and only running on 3 cylinders a sbc shakes a lot.
Hope its something easy.
CoryM

mooneyes · 08-18-2003, 09:15 PM

......i never thought of a slipped balancer...i'll have to check that..i do know its not wobbling any..i'll also check the fan..as for ignition or plug wires..i could take the thing out on the road and just smoke em...still runs great just a very scary vibration...as for another motor Randy im working on getting a small journal 327 of 6772 king...and the only work i've done lately is putting in the tranny....thanks guys.....

tom hand · 08-18-2003, 09:17 PM

I saw a 4-71 detroit run with a broken crank but I dought that is your problem. Put on some thick gloves and pull one spark plug wire at a time and see if it runs differently as you pull each one. If its slows down...that cylinder was doing its job. If it makes no difference that cylinder is doing nothing. If it speeds up [and you really don't want this] the cam is flat on that cylinder. Good Luck

Class of 69 · 08-18-2003, 10:20 PM

Did you change flex plates with the tranny install???

cableguy0 · 08-19-2003, 12:26 AM

class of 69 brought up a good point maybe if you did swap the flexplate the new one isnt balanced right

08-17-2003, 08:31 PM	#1
mooneyes Registered User Join Date: Jan 2002 Location: Slippery Rock PA USA Posts: 1,692	engine vibration? .....got a vibration so i unbolted my torque converter to make sure it wasn't the tranny and now its 3 times as bad...i guess the converter was dampning the vibration...everybody i talk to said the only time they saw this was with a broken crank!!!!...damn i dont know how i would have done that...going to try to get it out this week and tear it down...anybody ever have this prob.? __________________ Ken Lyons, Slippery rock pa 68 short step 327 t10 4 gear 72 2wd blazer project 70 lwb 305/700r driver 78 caprice project 02 cavalier D.D ( hate it!!)

08-17-2003, 08:57 PM	#2
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,326	any time ive had a broken crank the motor wouldnt work at all __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

08-17-2003, 09:00 PM	#3
68 Stepside huh? Join Date: May 2000 Location: Washington, Illinois Posts: 5,690	how about a bad/slipped harmonic balancer? __________________ Someday when I'm lonely, Wishing you weren't so far away, Then I will remember Things we said today. RIP El Jay

08-17-2003, 11:35 PM	#5
weasel29gm SLOW BUT SURE,BUT CLOSER Join Date: Feb 2002 Location: eleanor wv usa Posts: 3,101	Check all your mounts motor and tranny. A buddy had the same thing and turned out to be the tranny mount. __________________ 69 C-10, OWNED 38YRS... 350 over 30, 350 Turbo, 3:73 Posi P/S, P/B Black with red and black int. ''LOVE THESE OLD ''TRUCKS.......

08-18-2003, 08:25 PM	#6
cb Registered User Join Date: Oct 2000 Location: Gilbert, AZ USA Posts: 98	If it is vibrating a lot, check the fan. You loose one blade and it shakes real bad. It is not a broken crank. __________________ Craig Berland

08-17-2003, 09:00 PM	#4
Randy70C-10 Account Suspended Join Date: Mar 2001 Location: Virginia Beach, Va. U.S.A. Posts: 15,320	I don't know, but if you want to upgrade I have a 350, 260 horse engine with less than 2,000 mile on a complete rebuild. I swapped a ZZ-3 in it's place so now I have a spare engine. Another board member was asking about it but I haven't heard from him lately. Oh.......$900.

08-18-2003, 08:43 PM	#7
Gordo Registered User Join Date: Jan 2001 Location: Killingworth, CT. USA Posts: 3,378	I remember running a big block 460 cu in F*rd that had a broken crankshaft and there was a SERIOUS noise that went with the vibration. Took it apart later and it was infact broken in two between the first and second main bearings. I really doubt that is your case. Is it possible a couple of plug wires got mixed up or maybe moisture under the dist cap? Have you done any work on it lately or made any changes? __________________ 1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist.

08-18-2003, 09:08 PM	#8
CoryM Registered User Join Date: Dec 1999 Location: Surrey, B.C. , Canada Posts: 874	Ive seen a ferd break a crank and it still ran with no noises. However the crank pulley was moving in and out about 1/2". Make sure its not just having ignition troubles. With a bad mount and only running on 3 cylinders a sbc shakes a lot. Hope its something easy. CoryM __________________ 1970 heavy duty C-10 fleetside sport truck. Vancouver B.C. Canada http://www.geocities.com/chevroletc1070 "Take up our quarrel with the foe: To you from failing hands we throw The torch; be yours to hold it high." Lieutenant Colonel John McCrae, Canadian Army

08-18-2003, 09:15 PM	#9
mooneyes Registered User Join Date: Jan 2002 Location: Slippery Rock PA USA Posts: 1,692	......i never thought of a slipped balancer...i'll have to check that..i do know its not wobbling any..i'll also check the fan..as for ignition or plug wires..i could take the thing out on the road and just smoke em...still runs great just a very scary vibration...as for another motor Randy im working on getting a small journal 327 of 6772 king...and the only work i've done lately is putting in the tranny....thanks guys..... __________________ Ken Lyons, Slippery rock pa 68 short step 327 t10 4 gear 72 2wd blazer project 70 lwb 305/700r driver 78 caprice project 02 cavalier D.D ( hate it!!)

08-18-2003, 09:17 PM	#10
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	I saw a 4-71 detroit run with a broken crank but I dought that is your problem. Put on some thick gloves and pull one spark plug wire at a time and see if it runs differently as you pull each one. If its slows down...that cylinder was doing its job. If it makes no difference that cylinder is doing nothing. If it speeds up [and you really don't want this] the cam is flat on that cylinder. Good Luck __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

08-18-2003, 10:20 PM	#11
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	Did you change flex plates with the tranny install??? __________________ 69 GMC K10 ..some restoration required....still..

08-19-2003, 12:26 AM	#12
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	class of 69 brought up a good point maybe if you did swap the flexplate the new one isnt balanced right __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.



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