put a water pump on my 1999 z28. got her back together now i have a viberation from say 600rpm to 1,000 rpm when in park or neutral. when its in drive its not even really there, it didnt start doing this until i installed the water pump. its like the whole motor shutters barley at 600rpm and as it goes up to a 1,000 it gets worse but then goes away after 1,000rpms. any idea where i did something wrong or what went wrong?

 

stop starting/running the engine.

Check the pulleys, make sure they're lined up. Make sure the water pump is fully seated and not ****-eyed. Maybe a bolt isn't all the way in. Spin the bell housing and see if it wobbles at all.

If that belt is off balance you can damage the internals of your engine by running it.

 

Check to make sure the sensors on the air box (MAF & IAT) were plugged back in after the job.

 

everything is plugs back in, the pulleys appear to be all lined up and i no the belt is in all the groves, i changed out the crank pulley the other day because it had some slight wobble to it but the new one does just the samething. and i believe it isn;t **** eyed, so that makes me have to look at the bellhousing now, but its just wierd because it only does this in park and neutral and between the rpms like stated above. any other time its gone and fine.

 

The new one DOES THE SAME THING. There's your problem most likely. They are NOT supposed to wobble.

 

but if it was the balancer wouldnt that get worse as rpm increases? This disappears basically in drive and disappears in neutral or park after 1,000 rpm

 

No, it would not necassarily get worse. It depends. Some will only vibrate at higher rpm's, yours it happening at low rpms. But I can tell you this and so will any smart engine builder.....you are damaging your internal parts (crank, rods, bearings) if that system is off balance at all.

 

could it be a possiblity that i got a bad water pump too?

 

I suppose the shaft could be bent and causing the wobble in the serpentine system. Sure.

Thats why I said to spion the bell housing and see if it spins perfectly straight with no wobble. If its ok, then maybe your crank pulley wheel is not quite perfect. Take it off and remount it.

 

Yes its possible. Start the car and watch the waterpump and crank pulley. If you have to, get a timing light and shine on them to slow the rotation down so you can see it easier.

 

thanks for the information guys.... ill check it out as soon as we have a non rainy day, i just thought it had something to do with the water pump being that it didn't do this viberation till after i replaced it right at start up

 

I think it could be a bad water pump. Don't rule it out.

LIke I said, make sure the entire pump is seated straight agaonst the block. The bell housing might spin perfectly straight with no wobble and the shaft may be fine, but the entire pump might be slightly crooked. Maybe loosen all the bolts a little bit so the pump moves, then tighten it back down, the gaskets will be fine.

 

Start the car with no belts installed for a very short time.

This will tell you if it is the harmonic dampner or something else on the drive belt system.

 

well we shall no for sure this weekend... taking water pump off and getting a new one

 

Sounds like fun.

 

when installing the water pump. do you put the gaskets that go on the back of the water pump on dry or do you put a thin layer of rtv or some kind of sealant on them?

 

they do not need any rtv.
i always put a lil dab in a couple spots to keep them in place while positioning the pump.
they like to move around, and it can become a headache.
dont use a gob, its not needed.

 

This may be important:

22lb-ft on the water pump mounting bolts.