Stumped with a viabration

[pontiacgp]

I have had a vibration somewhere in the drive line, not real bad but it's a nuisance. . It used to be at around 2100 rpm and you could feel it with the clutch in. The flywheel had been refaced but not balanced so I thought it could be that. I changed the flywheel with a virtually new one and the vibration was still there but at about 3100 rpm now. I was thinking it's probable the pressure plate and when I put it back on after changing the flywheel I probably changed the pressure plate's orientation. I have a new Hayes performance pressure plate and clutch to install this winter. The pressure plate was balanced the zero by the race team that was going to use that set up and I thought that will solve the vibration

Something happened the other day that throws my theory in the garbage. My intake is leaking a bit of oil into a couple of cylinders so I have to top the oil up every once on a while. I have new gaskets to install this winter. A friend was topping up my oil and he managed to over fill it by about a litre (close to a quart). I was not too worried cause I'm not planning to run the car hard and am parking it real soon for the winter. With that extra oil the vibration almost went away. The dipstick in my car shows the right level. I have a 7 quart pan and with the filter 8 quarts shows the stick as full. My oil pressure is perfect. I talked to a friend who has been building engines for years and owns a speed shop. He has no clue what it could be. I'm wondering if any of you guys have come across an issue like this.....thanks for reading and hopefully someone here has the answer.

 

[UMI Sales]

Sounds to me like next time you change the oil you should pick up 9 quarts of oil!!

Gotta love when things like that happen.

Craig

 

[V8 Rumble]

Is the vibration still gone with the overfill? Maybe a u joint going? A drive shaft weight? Wheel weights?

That is very strange that it went away by over filling. I am stumped as well.

 

[clean8485]

Judging from what you're saying Steve, you have an internal engine issue. That would account for the RPM change when you replaced the flywheel. Does the engine have a windage tray? I'm just wondering why the oil overfill is dampening the vibration. I have to admit that I'm stumped as well.

 

[jeremyandthemonte]

The way I look at this is we have to go back and make things simple. Engine has a lot of moving parts but what is big enough to cause a vibration? Crank? Now if we add more oil that oil has to go somewhere. Me I have no clue what could cause it but process of being dumb and keeping it simple could help

 

[Bonnewagon]

I really can't think of why the extra oil would affect anything unless the spinning crank is grabbing some. But that usually results in oil foaming. I would go back to the original build- who built the engine and how was it balanced? Factory built with factory balance with the flywheel? Engine zero balance and flywheel zero balance? You can't just swap flywheels around unless they are all match balanced by whatever procedure was used. Before and after surfacing a flywheel should always be checked and re-balanced if necessary but not a lot of machinists can handle that so they ignore it. I have had quite a few bad flywheel surfacing jobs that made driving a PITA. Then the pressure plate should have been zero balanced by the manufacturer, why was that even questioned? Does the team have the equipment for such a task and the know how to accomplish it? My 301 was balanced by a professional shop that factory balanced the engine and flywheel as a pair then match balanced both a manual flywheel and an automatic flex plate so I could use either kind of transmission.

 

[pontiacgp]

no windage tray and the oil pressure is the same as when the oil was at the proper level. The engine was rebuilt by a builder unknown to me. It was used and when I changed the heads all the pistons were .30 over unlike some rebuilds with only over size pistons where needed. When I first installed it I had the auto transmission so the vibrations did not seem to be there but there was a harmonic vibration. . Last year I changed my T5 wc to one of my spares but that didn't stop the vibration. That's why I changed the flywheel this year. I even beat on the engine in different gears at the rpm with the vibration lots of times so see if anything would break but nothing did. Once past the rpms with the vibrations I can rev it up to 6,000 with no viabrations

 

[pontiacgp]

Is the vibration still gone with the overfill? Maybe a u joint going? A drive shaft weight? Wheel weights?

That is very strange that it went away by over filling. I am stumped as well.

it's not about weights, you can feel it sitting still reving the engine up to the rpm, clutch in or clutch out

 

[455'ed80Regal]

Sounds like my 383 I had in my IROC Z. Engine was internally balanced. New Centerforce flywheel and DF clutch & pp. After a lot of frustration, I came to the conclusion it was a bad clutch and/or pressure plate.

 

[pontiacgp]

Sounds like my 383 I had in my IROC Z. Engine was internally balanced. New Centerforce flywheel and DF clutch & pp. After a lot of frustration, I came to the conclusion it was a bad clutch and/or pressure plate.

that's what I was thinking, but why does the overfilled oil dampen the vibration...that's what I can't figure out. I have the center force pressure plate .