Motor Vibration, idle to 1800 RPM the worst!

[waynep]

Hello All:

Strong motor area vibration from idle to around 1500 to 1800 RPM. Looks like front of the motor is actually shaking. Does not seem to get much better when warm, just a little.
Seems to have same amount of power etc, but getting more and more noticeable when starting.

Motor also seems to be a bit more noticeable noisey.

Exhaust may be touching frame, I will check.

Any ideas? 1997 3/4 Ton subway 4 WD.
Regards,
Wayne

[trbankii]

Start by checking out the harmonic balancer and the motor mounts.

[racer55]

If the Harmonic balancer or the front crankshaft pulley are becomming unbonded they can make a great deal of noise and can lead to a broken crankshaft-get this dealt with ASAP before you have the chance to loose your engine!

[Robyn]

Start by removing the serp belt and then checking the crank pulley.

If the pulley is loose and or can be moved easily back and forth, therein lies the issue.

These pulleys are rubber bonded with a bearing to pilot the drive rim.

There is also two guide studs that go through the inner hub in case the rubber breaks loose.

The pulley comes of easily with the removal of 4 bolts.

If the pulley is OK then look at the ballancer for signs that the outer ring has slipped.

With the belt off, start the engine and see what happens. Watch the ballancer and pulley.

If you remove the top half of the fan shroud you can get at this stuff easily.

Cont run the thing with the belt on and the shroud off, you can easily get tangled in the fan.

Be careful any time you are running the thing and poking around.

With the shroud off and the belt off and even removal of the fan (four nuts) will give you a really good look at the ballancer and the pulley.

The puley is easy to replace as is the ballancer.

The ballancer required a two arm puller. (dont pull on the outer ring)

Use the bolt holes that retain the pulley. You can also use the pulley bolts with many pullers to get the ballancer off.

There is a large bolt in the center of the ballancer that retains it to the crank.

These are many times retained with some locktite.

An impact wrench makes this much easier.


Good luck

Missy

[waynep]

You guys are good. The main center bolt on harmonics was loose and key and keyway shot. Should I replace the balancers even if they look OK. Also should I replace the bearing likewise. How hard is it to replace ? And any tricks and tips. I have the shop manual.
Bearing looks/feels OK but since I am in there. Keyway on crank a bit damaged but a new key and locktite I hope will fix? Thoughts.
Thank you, Wayne

[waynep]

Hello All:

Sorry misspoke, it looks like an oil seal not a bearing, but same questions. Any experiences also with the various aftermarket parts?
Thank you, Wayne

[rameye]

I wonder why it came loose in the first place?? Balancer going bad could have shook itself loose.


Just for ha ha's...after you get all the bad parts off....why dont you either use a dial indicator and check the crank run out or start it and eyeball it....does it wobble....yes = game over.


I would replace that balancer...even if it looks OK....too much of a risk.

File and clean the keyway...buy a new key and file it to fit snugly...loctite will not help a sloppy keyway...not even the green.

Pull the seal and replace...not too bad.

Polish the crank with scotchbrite, emery or I have good luck with a roll of that plumbing prep...go medium then to fine before popping in the new seal.

When shes ready it will shine brightly.

Keep us informed.

[JohnC]

... start it and eyeball it....does it wobble....yes = game over.

Start it without the balancer? I would not recommend that!

[rameye]

briefly...atleast you can see if its out of whack by sight if you cant, or dont know how to indicate it....my shade tree alternatives are not always the best..

[waynep]

Hello All:

Even though the crank keyway was damaged, the balancer did not "wobble" too bad so I am hoping that the crank is OK.

Also, the old oil seal did not leak, if that tells me anything about potential crank damage?

Replacing all and crossing my fingers that when I start it up the vibration all goes away?

Thank you and appreciate any and all comments.