Engine vibration while truck not moving in park - The 1947 - Present Chevrolet & GMC Truck Message Board Network

skokie · 11-05-2022, 06:36 PM

Well its been a while. I am back in the 67-72 chevy truck game. I have a vibration while the truck is running and in park. 68 Chevy 350 crate motor, hei dizzy, 400 turbo rebuilt with roughly 3000 miles on it, new TCI flex plate. Truck is up north and I am heading up there next weekend to work on it and see if I can find the issue.

The plan is check all of the plug wires to make sure they are all connected etc, then pull all of the plugs to see if someone is not contributing, if that shows all good then I may go as far as separating the transmission from the engine and pulling the flex plate to see if that solves it.

Anything else I can check?

Thanks!

tutone · 11-06-2022, 03:00 AM

Before I did all that, I would pull my v belt(s) off then crank it for a minute to make sure it isn't an accesory up front. If your new flex plate is for a sb 400 and externally balanced, it will cause vibration. Believe it or not, I just saw that on a BB this week.

skokie · 11-06-2022, 03:08 AM

Quote:

Originally Posted by tutone

Before I did all that, I would pull my v belt(s) off then crank it for a minute to make sure it isn't an accesory up front. If your new flex plate is for a sb 400 and externally balanced, it will cause vibration. Believe it or not, I just saw that on a BB this week.

Good suggestion. I will add removing the belts to the list. Also its a 350 not a SB400. It has a 400 turbo tranny in it.

Thanks!!

**special-K** · 11-06-2022, 07:01 AM

Quote:

Originally Posted by skokie

Good suggestion. I will add removing the belts to the list. Also its a 350 not a SB400. It has a 400 turbo tranny in it.

Thanks!!

Tutone I think was giving another possible cause, a 400 flex-plate on a 350. Have you checked the torque convertor bolts?

**CC69Rat** · 11-06-2022, 09:49 AM

I agree with tutone- Sounds like the flexplate has weights on it. (Externally balanced) Incorrect for a 350 engine.

I have also ran into this with Big Blocks.

skokie · 11-06-2022, 04:26 PM

I forgot about that. Thanks tutone!!. I am pretty sure it was for a 350 not a 400 but I will check. Its been a while. I have to get the rust broken off

Myself · 11-07-2022, 10:41 AM

Long tube headers bumping against the frame?

skokie · 11-07-2022, 03:41 PM

Quote:

Originally Posted by Myself

Long tube headers bumping against the frame?

Nope. Ramhorn exhaust.

purple gas · 11-14-2022, 02:06 PM

This problem is probably rare, but it happened to me.
Shortly after I started driving my truck after swapping engines it would shake violently at idle sometimes when I stopped.
After a bit of head scratching I discovered my dist would not return to idle position after revving it up.
It had been sitting for who knows how long and the distributor was corroded and sticky.
Took it apart, cleaned it up and it worked fine after.

**bowtie72** · 11-19-2022, 10:42 AM

You can give the balancer a look. Check to make sure the outer hasn’t moved and if the rubber is in good condition.

**old51sedan** · 11-19-2022, 04:14 PM

Also check fan blade, a friend of mine had part of his break off on his chenille, had a heck of a time trying to find out what was wrong

PowerdbyChevy79 · 11-24-2022, 06:44 PM

I had a similar issue with a 82C20 I worked on. Truck had a brand new engine that had never been ran. After breaking it in and putting shakedown miles on it, it developed a bad vibration. Got worse when accelerated. Went thru the regular troubleshoot list and found nothing. Replaced the balancer as last resort before pulling the engine and taking it to the machine shop. Found the balancer was bad, it had dry rotted. My one and only time I had a bad balancer. Check to make sure you have the correct flexplate also.

11-05-2022, 06:36 PM	#1
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,354	Engine vibration while truck not moving in park Well its been a while. I am back in the 67-72 chevy truck game. I have a vibration while the truck is running and in park. 68 Chevy 350 crate motor, hei dizzy, 400 turbo rebuilt with roughly 3000 miles on it, new TCI flex plate. Truck is up north and I am heading up there next weekend to work on it and see if I can find the issue. The plan is check all of the plug wires to make sure they are all connected etc, then pull all of the plugs to see if someone is not contributing, if that shows all good then I may go as far as separating the transmission from the engine and pulling the flex plate to see if that solves it. Anything else I can check? Thanks! __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

11-06-2022, 03:00 AM	#2
tutone Registered User Join Date: Mar 2016 Location: hickory, ky Posts: 1,311	Re: Engine vibration while truck not moving in park Before I did all that, I would pull my v belt(s) off then crank it for a minute to make sure it isn't an accesory up front. If your new flex plate is for a sb 400 and externally balanced, it will cause vibration. Believe it or not, I just saw that on a BB this week. __________________ :My build thread http://67-72chevytrucks.com/vboard/s...d.php?t=807535 1972 K10 swb/1968 Camaro 350/4spd 1955 210 2 dr sedan/1998 RCSB Z71/1977 Jeep CJ5

11-06-2022, 09:49 AM	#5
CC69Rat Registered User Join Date: Jan 2011 Location: Chattanooga TN Posts: 6,214	Re: Engine vibration while truck not moving in park I agree with tutone- Sounds like the flexplate has weights on it. (Externally balanced) Incorrect for a 350 engine. I have also ran into this with Big Blocks. __________________ Chad 1967 C10 SWB - Project Savannah - 6.0/4L80 Currently underway 1968 C10 SWB - TOTY 2018, 50th Anniversary Tribute Project * Sold * Pride and Joy 1986 Silverado Short Fleet - Scarlet Sold 1985 Silverado Short Fleet Sold 2022 Jeep Gladiator Mojave 2001 Jeep Cherokee XJ 4x4 - Lifted, Built 1992 Jeep Cherokee XJ 4x4 - Lifted 2013 Honda Accord EX-L v6 Coupe 6spd (wife's ride)

11-06-2022, 04:26 PM	#6
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,354	Re: Engine vibration while truck not moving in park I forgot about that. Thanks tutone!!. I am pretty sure it was for a 350 not a 400 but I will check. Its been a while. I have to get the rust broken off __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

11-07-2022, 10:41 AM	#7
Myself Registered User Join Date: Oct 2005 Location: Northern Arkansas Posts: 1,144	Re: Engine vibration while truck not moving in park Long tube headers bumping against the frame?

11-14-2022, 02:06 PM	#9
purple gas Registered User Join Date: Oct 2004 Location: saskatoon, planet earth Posts: 694	Re: Engine vibration while truck not moving in park This problem is probably rare, but it happened to me. Shortly after I started driving my truck after swapping engines it would shake violently at idle sometimes when I stopped. After a bit of head scratching I discovered my dist would not return to idle position after revving it up. It had been sitting for who knows how long and the distributor was corroded and sticky. Took it apart, cleaned it up and it worked fine after. __________________ I got a bench seat baby, you don't have to sit over there.

11-19-2022, 10:42 AM	#10
bowtie72 Registered User Join Date: Mar 2007 Location: Colorado Posts: 363	Re: Engine vibration while truck not moving in park You can give the balancer a look. Check to make sure the outer hasn’t moved and if the rubber is in good condition. __________________ 1968 SWB "Little White Truck" 1972 LWB LS 4l80 "Plain Jane!!"

11-19-2022, 04:14 PM	#11
old51sedan Senior Member Join Date: Oct 2015 Location: Williamston, Mi Posts: 885	Re: Engine vibration while truck not moving in park Also check fan blade, a friend of mine had part of his break off on his chenille, had a heck of a time trying to find out what was wrong

11-24-2022, 06:44 PM	#12
PowerdbyChevy79 Registered User Join Date: Apr 2013 Location: Houston,Tx Posts: 790	Re: Engine vibration while truck not moving in park I had a similar issue with a 82C20 I worked on. Truck had a brand new engine that had never been ran. After breaking it in and putting shakedown miles on it, it developed a bad vibration. Got worse when accelerated. Went thru the regular troubleshoot list and found nothing. Replaced the balancer as last resort before pulling the engine and taking it to the machine shop. Found the balancer was bad, it had dry rotted. My one and only time I had a bad balancer. Check to make sure you have the correct flexplate also. __________________ 1966 C10 "Mary" 1972 C10 Cheyenne "Betty" https://67-72chevytrucks.com/vboard/...d.php?t=847364 1979 C10 Silverado "The BIG TEN" https://67-72chevytrucks.com/vboard/...d.php?t=841339 C10 Club Texas -HMIC



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