Start engine with no tranny attached?
Thread Starter
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
Start engine with no tranny attached?
I am trying to find a vibration in the engine and struggling, the vibration only happens from 3000 rpm and up. Vibration happens with car in neutral, clutch engaged or disengaged.
Bought new plug wires, plugs, distributor cap and rotor
I have checked the Ohm's on the injectors, OK
Fuel Pump pressure is good throughout the rev range.
No bent valves per the leak test at 50-psi
Roller Lifters appear to be solid
Distributor gear is good, not worn
Clutch disc, PP and FW checked OK
So can I start engine with no tranny attached to check for the vibration without the tranny?
Bought new plug wires, plugs, distributor cap and rotor
I have checked the Ohm's on the injectors, OK
Fuel Pump pressure is good throughout the rev range.
No bent valves per the leak test at 50-psi
Roller Lifters appear to be solid
Distributor gear is good, not worn
Clutch disc, PP and FW checked OK
So can I start engine with no tranny attached to check for the vibration without the tranny?
Thread Starter
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
IB. Anyway, here are some other examples showing operation with PP
and w/ FW & C.
I keep expecting this guy to say 'it's got cop tires, cop suspension,
cop shocks ...'
Here is an SBC with PP, C & bell housing
.
Le Mans Master
Joined: Jan 2002
Posts: 9,036
Likes: 13
From: Edmonton AB
I started off on the Internal/External balance discussion because I
failed to fully read LD85's post and had it in my head that he wanted
to isolate operation solely to the engine's rotating assembly by
excluding the transmission AND flywheel & ect.
Add this contretemps to my Oops count.
.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
A mistake!! 
I picture a Transmission bearing wrapped gifts.....
I think you meant "presence".....just a little fun on a Tuesday morning.
OP whether or not you get to open a gift....CFI is right(as usual)
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
run engines
run the engine, but look at the accessories, alternator, air cond, pulleys, etc. usually you are feeling the harmonics of the serpentine belt
system.
I would first start it cold without the serpentine belt for a few seconds rather than pull the trans. No longer than 60 seconds.
If you still have the vibration, shut it off, put the belt back on, and note the difference and let the engine cool off or warm up.
Then if you want to go the other route and take off the trans, then go for it. You will probably want to inspect the harmonic balancer really good before you take the trans out.
Sometimes the balancer is the culprit as well as an out of round pulley or accessory.
system.
I would first start it cold without the serpentine belt for a few seconds rather than pull the trans. No longer than 60 seconds.
If you still have the vibration, shut it off, put the belt back on, and note the difference and let the engine cool off or warm up.
Then if you want to go the other route and take off the trans, then go for it. You will probably want to inspect the harmonic balancer really good before you take the trans out.
Sometimes the balancer is the culprit as well as an out of round pulley or accessory.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by jhammons01
Aha!!! A mistake!!
I picture a Transmission bearing wrapped gifts.....
I think you meant "presence".....just a little fun on a Tuesday morning.
OP whether or not you get to open a gift....CFI is right(as usual)
A mistake!! I picture a Transmission bearing wrapped gifts.....
I think you meant "presence".....just a little fun on a Tuesday morning.
OP whether or not you get to open a gift....CFI is right(as usual)
RACE ON!!!
Le Mans Master
Joined: Dec 2002
Posts: 5,270
Likes: 3
From: Seattle Area WA
Curious to hear your results I have a weird slight vibration at ~3.5-4k. It isn't bad and goes away after that point. It definitely isn't bad enough to be an out of balance motor (ext balanced) I'm thinking it is the dampner. But I'll have to try that serp belt test and I'm very interested to hear your results.
Good luck!
Good luck!
Le Mans Master
Joined: Mar 2001
Posts: 9,464
Likes: 1
From: Modesto CA
I'm sure you've already checked this...
but on my 85 many moons ago, I had the stock balancer come apart, and everything was fine, but it would have an odd vibration in the mid-range rpm's...so, just something to think about...
but on my 85 many moons ago, I had the stock balancer come apart, and everything was fine, but it would have an odd vibration in the mid-range rpm's...so, just something to think about...
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by BrianCunningham
If you leave the clutch attached and the transmission input shaft isn't there, what are you going to use to center the disk?
RACE ON!!!