I've got a slight "engine" vibration, any ideas?

99FiveOh · Nov 4, 2006

My 95 has developed a vibration that gets worse with engine RPM, whether the car is moving or not. If I'm cruising 80 or 90mph and pull the car out of gear, it will be smooth as silk.

If I'm sitting in traffic and I rev the motor up around 3000 rpm and up I can feel the vibration.

My balancer is relatively new, I look at it and it's spinning nice and true with no rubber coming out. All my mounts are new. The clutch is pretty old and is a King Cobra clutch. The flywheel looked pretty good last time I had the tranny out.

The engine has great oil pressure and I don't hear any loud knocking or anything. Now, awhile back the car would knock for a second when it was starting in the morning then go away when I got oil pressure. I changed the oil and the knocking has gone away since. I do hear a slight "tapping" noise that sounds like it's coming from the top portion of the engine, but I'm thinking that's just a rocker arm or something.

Has anyone ever had a main bearing or crank bearing go out or spin? What does that feel like? My car still has all the power it did before and doesn't smoke a bit! I would like to rule out any internal damage to the engine because I want to install an S trim soon.

Any help or advice would be appreciated. Remember, it vibrates while stopped, so I know the driveline isn't to blame. Please don't go blaming the tremec the car drives smooth while in motion. Thanks!

wytstang · Nov 5, 2006

Wires? plugs? cap & rotor? are they new, old when was the last time you changed your fuel filter?

99FiveOh · Nov 5, 2006

This is a mechanical vibration for sure. I doubt the fuel filter would cause it, and besides, it's been changed not too long ago.. beginning of the year actually.

I've ran cars with fuel filters that were 5-6 years old and didn't cause a vibration. That would just cause a bad miss or backfire when you rev the engine. Besides, I have a pressure gauge and it's reading about 38psi at idle and stays consistant while reving the engine.

My car has a slight vibration that feels like a pretty quick frequency, faster than that of a bad balancer.

Could a bad pilot bearing cause a vibration? I had it go bad before, but no vibes, it just made shifting impossible because it would grab hold of the input shaft and spin it along with the engine.

back2fox · Nov 11, 2006

Have you figured it out? I'm having a similar problem. I pulled the tranny out last week and everything was fine. I replaced the clutch, pilot bearing, and resurfaced the flywheel just in case.

I started the engine with the tranny out to check if the flywheel would wobble or something, but it was smooth. Put everything back and it still vibrates. Pulling the tranny out and opening it up this weekend. Just drained the fluid and it had a metallic look to it.

99FiveOh · Nov 11, 2006

Mine vibrates with the clutch pushed in so that eliminates the tranny all together for me. My problem is between the balancer and flywheel or internal. I've got a rebuilt engine I'm going to be putting in after I have it checked out by a machine shop. It will have new everything!

chefster · Nov 12, 2006

ya me too at 5000 gettin on the eway in 4th gear .....i figure maybe the gear spacing in the rear end.oorr a harmonic balancer alittle out of whack

back2fox · Nov 17, 2006

The_Mustang said:
Mine vibrates with the clutch pushed in so that eliminates the tranny all together for me. My problem is between the balancer and flywheel or internal. I've got a rebuilt engine I'm going to be putting in after I have it checked out by a machine shop. It will have new everything!

I guess mine wasn't the tranny after all. It is definately something internal. Either wrong balancing between the crank and balancer or a messed up crank. I will be tearing my engine down soon to figure it out. good luck with yours. I've just about replaced everything but the motor at this point.

99FiveOh · Jan 30, 2007

well, I swapped in another clutch today and all is good! I found a really glazed pressure plate and flywheel and a worn out disc and throwout bearing. And the Pilot bearing was toast! It's nice to have a smooth car again!

rj95svt · Jan 31, 2007

I am having a problem with my car as well. I thought it was the harmonic balancer and part of it was. I bought a new pioneer balancer and it still has some vibration although my factory balancer was wobbling and the ring had slipped. My car had been sitting for awhile before I bought it (long enough that the flywheel was covered in rust the first time the engine was cranked. I'm now thinking that I need to get the flywheel surfaced, a new pilot bearing, and clutch. The car only has 63,000 miles on it and the engine has great oil pressure so I'm sure that this is the problem.

99FiveOh · Feb 13, 2007

Well, I guess I didn't fix it afterall. I wanted it to be fixed so bad that I must have imagined it being fixed.

So, just today I installed a brand new balancer. No change! I can't see the flywheel going bad because it's a solid piece of iron, no weights to fall off. And, I had it wrong before. If I'm at a stop and rev the engine slow, it revs up nice and smooth, but if I goose the throttle I can feel it like a mofo. I'm at my witts end with this engine vibration.

I'm starting to believe that my motor is going bad. Doesn't make sense though because my oil pressure is better than good, the engine is smooth at idle, I don't hear any knocking noises and it doesn't smoke at all. What could go bad inside an engine but still have good oil pressure and smooth idle?

BlownFiveLiter · Feb 13, 2007

I'd go over the usual suspects starting with the easy stuff. Plugs (gapped the same? clean?), wires, cap & rotor, no vacuum leaks, no codes, etc. If all of that checks out, you mentioned before about a tapping that you thought was a rocker. Ever look into that? A loose rocker probably wouldn't be enough to cause some heavy vibrations, but if it's not opening the valve the same as the other cylinders, you may be down on power in that cylinder and feeling the difference more when you open the throttle. How about a compression test?

99FiveOh · Feb 13, 2007

I just ran a cylinder balance test and it checked out ok. I know there's a vacuum leak behind the upper intake, I can hear it when I move the hose around. I can't see a vibration being caused by a vacuum leak. Anyone ever had that happen?

I'm about to install an S trim this weekend so I'll get that vacuum leak changed and I'm installing some 9mm FMS wires, NGK plugs and a new MSD cap and rotor. I guess I'll do all that and see where I'm at. I'm sure huffing some power into the motor will either confirm that it's ok or show me what's wrong rather quickly!

99FiveOh · Feb 13, 2007

one thing I haven't considered is the exhaust. Does having flowmasters that are dumped cause more vibes than when there's tailpipes? I'm sure it does, but I'm not sure to what extent.

fordtech28 · Feb 14, 2007

if you have new motor mounts you will feel more vibration from your motor until they break in also if you have your flowmasters dumped you are definately going to have more vibration when you rev it up

99FiveOh · Feb 14, 2007

well, the motor mounts aren't brand new, they are about a year old.. but new in relation to the old ones of course.

I've got a slight "engine" vibration, any ideas?

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