I can't pinpoint where it's coming from, but when the cooling fans come on it vibrates the car. The car idles perfectly smooth until they come on. I've recently replaced both fan motors, made sure everything is bolted tight, and nothing is hitting the fan blades when their on. I get the feeling something is hitting the frame of the car because you can feel it throughout the car. If anybody has any ideas on this it would be greatly appreciated.

 

hmm that is weird, if there in place and tight and hitting anything not sure how they could be causing vibrations.

hows the fan blades? one could be cracked alittle and when they get up to speed it starts to shake things up alittle.

 

how bad is the vibration? when my fans come on i can feel a slight vibration through the steering wheel. but this is more so when the car is off and the fans are on. when the car is running the noise from the engine kinda cancels out the vibration.

but chances are the vibration is coming from your fan blades being unballanced.

 

It may be the alternator/battery. When the fans come on, it may be putting such a draw on the battery, the alternator must work extra hard pulling the motor down, possibly causing the vibration.
just a thought,
Mark

 

good point. what amp alternator are you running and are your bearings good? it might be a good time to get it rebuilt

 

Check the accessory bracket to engine block mounting bolts... I once had a strange vibration when I engaged my A/C... turned out to be the alt/ps bracket vibrating under the increased belt load because the mounting bracket was loose (did NOT see that one coming).. I chased that bastard for a while until I discovered that...

Perhaps the increased load on the alternator is a similar effect...

 

I have a problem similar to this except my noise is more grinding of something than shaking. Any solutions?

 

haven't found the problem yet. Tried re-hanging the fans and still get vibrations. I am going to take evrything out of there and put it back in when I get some time. We'll see what happens.

 

Perhaps the plastic fan blades are out of balance (read damaged)... did you inspect the plastic fan blades for damage/warpage??

 

try using a jumper to run them with the car off.. and then put your hand on the motor of the fan and see if u feel any vibration. that'l help eliminate the other possibilites.