Balancing an engine?

[CELT4RAGTOP]

Has anyone ever heard of an engine needing to be balanced?

I purchased a 96 LT4 6spd a few weeks ago and have already had it back to the dealer twice for the same two problems, an oil leak and a wobble in the front end.

At first I thought the wobble was just the tires being out of balance, the dealer thought so too and tried to balance the tires. They said the oil leak was from a "linkage" that had an O-ring that was leaking. They replaced the part and everything was supposed to be OK.

However, it was still leaking oil and I still had the wobble (The wobble is most pronounced between 50 - 60 mph, but it seems to happen at different speeds and under different conditions, accelarating, coasting)

On the second trip to the dealer (I purchased the vehicle from Carmax), they said that the oil leak was from the manifold and they are fixing it. They are now saying that the wobble is becuase the engine is "out of balance" (They initially thought bad motor mounts) and that it needs to be balanced??? I believe he said the crank needed balancing???

Has anybody heard of such a thing? If they weren't doing the repairs on their nickel, I would think they were jacking me around, but I can't imagine they would be doing something unnecessary if its coming out of thier pockets.

Anyway, I've never heard of balancing a motor, but my experience is fairly limited.

Louis

 

[vigman]

WHAT A HUNK OF CR@P!

If it was the engine ( crank ) the motor would explode with THAT much imbalance!

Your soloution is probably a simple HIGH speed wheel balance.


Does the car shake side to side or up & down.

If you approach the speed..it gets progresivly worse?

Can you feel the shake in the wheel?

Mike

 

[vigman]

OR

You have a bad wheel bearing... but since you just bought the car...hey let em put a NEW engine in!

They PROBABLY did a bubble balance.( low speed & cheapo )


If the engine is OUT OF BALANCE ( that makes me SOOO! mad) the problem SHOULD show in 1 st gear with the engine @ the same revs as your cruising on the freeway.

How do the tires look?

Or a rim might be tweaked...

Mike

 

[DkBG]

The first thing I would try would be to switch the front tires to the rear and vise versa . If it's a bad rim or tire your car will shake alot more with it on the front .

 

[vigman]

Now to answer your question

A factory engine is balanced ( to some degree)

When you rebuild your engine and gather a bunch of NEW parts, pistons, rods,crank, flywheel,harmonic balancer.

All these things are spinning at a rather fast rate.

The object of this game is to make all the weight the same ( rods & pistons)

And not to have a heavy spot on the crank, harmonic balancer & flywheel)

An engine balancer will make sure all the rods & piston are the same weight... then connect them ( in a rather wild looking machine ) to the crank & the other bits and spin the thing up... it will tell the machinist to remove weight as needed ( like balancing your tires.. but far more trick)


Now a stock engine is balanced to the degree it needs to be for STOCK applications and that is a good job.

IF your going to RACE ( read professionally)
and the engine see's 5-7000 rpm all day long you will need a better job than stock.


Your Corvette is FINE and if anything.. a plug MIGHT not be firing ( causing it to run lumpy)


More info is needed!


Mike

 

[CELT4RAGTOP]

Mike,

The shake is side to side. I guess it does get progressively worse once you get to 50, but sometimes I get it when I'm simply coasting say from 40 to 30 with the car out of gear. But clearly it is worst in the 50 to 60 range.

There is some vibration in the wheel, heck the whole car seems to vibrate. I can see the rear view mirror quivering.

The tires look OK. They are Falkens? Never heard of them myself.

The rims look in good shape to the naked eye.

If they don't get it fixed this time I'll suggets swapping the tires to see where that gets me.

Louis

 

[vigman]

Something's fishy here

The rims MIGHT be tweaked on the inside of the rim.

The front bearing's MIGHT be bad.

The rack or ball joints MIGHT be bad.

You need to take it in to a dealer for an estimate.....( low cost...lot's of info )


Then take THAT paper and state you want those items FIXED or your money back!!!!!

Get tough..it's your cheese!

engine balanced ( from those guys... what a hoot!)

What's the warranty?


Mike

 

[vigman]

Falkens

Ok tire...not what's suppost to be on that baby!


Mike

 

[CELT4RAGTOP]

Mike,

Going to the dealer for the next step is good advice. I was thinking about doing just that.

I've got a 30 day warranty from Carmax (which I'm running up against now.) But I can assure you they will either fix it right or pay for the dealer to fix it. I have no prob tearin' somebody a new one if need be.

 

[vigman]

Get them to extend

The warranty..IN WRITING

Make a LIST of all the problem's that you are having NOW get them to recieve it ( VIA FAX from a chain like Kinko's & certified registered letter) that way they cannot contest your claims. As you crank this up they will start paying attention. Keep a log of all the previous warranty attemps and results.

Names Places Dates Paperwork...

You'll have them begging in a week.


Mike

 

[BigRed]

Mike Im also somewhat inexperieced in Corvette however, could it be:

Loose tyrod
The Aluminum housings in the rack and pinion have warped
Bad Ball joint
Collasped Shock/Spring

Just curious because when I first red the thread thats what I thought of mabe you could clear my head up :L

 

[vetsvette]

I had a set of Falkens once. Will never buy them again. I've heard of some people that like them but not me. They were not round. I don't mean they flat spotted over night. They were just not equally round. Gave me the same symptoms. Not an expensive tire. Maybe something to put on a car to sell it faster. "See, new tires". Take it to a good tire dealer and get them to high speed balance them. If they balance OK then you have eliminated one of the less expensive possibilities. Next I would probably get a good four wheel alignment. Eliminate that possibilty.

 

[vigman]

The bottom line here......

The car is obviously messed up.

You have to inspect EVERYTHING to take some of the guess work out. ( the dealer suggestion )


And the problems have to be broken into bite size chunks.


Mike

 

[ROCKO]

balancing an engine

I had the same problem with my 88 Vette. Lucky me the dealer who worked on the car was systematic and finally determined it was a tire out of balance. YOU CAN NOT BALANCE THESE WHEELS AND TIRES USING A BUBBLE MACHINE. What I think you need is somebody to go over your entire suspension. Also I once experienced the steel radials inside the tire going out of position which caused the car to shake side to side. An engine out of balance would be noticed at the same rpm in all gears. Good luck and I hope this helps.

Rocko

 

[FX3FX3]

96 wheels

you can't rotate to the front/back 96's wheels
285 vs 255...!!!!!

 

[vigman]

Good point!

Mike

 

[vetsvette]

If he has a Z51 car they are 275 all the way around.
ROCKO: did a tire dealer tell you the radials went out of position? :confused

 

[CELT4RAGTOP]

Update

FYI,

I sent a letter (5 pages certified, return receipt) to the head manager of the Carmax and a copy to the head service manager detailing not only the problems I've had, but also the lack of service.

I called to see where they were on the "engine balancing" and the service guy said that they had received my letter and that they were going to send the car to the Chevy dealer to diagnos the problem. Seems that they called the chevy dealer and their techs said it might be the clutch, but they would have to see it to know for sure. The service guy said it looked as though the prior owner put in a new clutch recently. Seems the dealer techs said that it has to be rotated in a particular manner and if its not installed properly, it may slip. You then have to take it out and rotate it 180 degrees and reinstall? They tell me this AFTER they've had the car a week already.

I'm giving them the benefit of the doubt, since they are sending the car to the dealer, but I'm about to lose it. I want my car and I want it fixed properly!!!

btw, the car only had 30K on it. Does it make sense that it needed a new clutch?

Also, what type of tires are recommended?

 

[vigman]

Gardening

Could ya pass some of that fertilizer over here!

For the same reasons it's not the engine..It cannot be the clutch.


If you rev your car up in neutral does it shake?
( clutch in or out will not matter)


If you want to verify it's the tires find a steep long hill and coast down it.

I'M NOT RECOMENDING THIS however,

In theory

You could have the engine off ( key on so the column isnt locked)

And when your coasting if the car still shakes... It's not the engine.

Now IF you do this remember you loose power brakes & steering.

So don't ( disclaimer )

So with the letter NOW I'll bet you have their attention! BAda Bing.

Goodyear Eagle GS-C's

Mike

 

[vigman]

30K clutch!

Not unless this person is doing his ( or Her)
burnout at every light.

or it has 130K on it have you run a Car Fax on it?

The more info... the better at this point

And seeing that these guys are having a problem just finding the morning doughnuts
I would trust NOTHING that they say... Talk to the Chevy tech DIRECTLY


Mike