I just got my 85 v6 today and the belts squeak and there is a TERRIBLE knocking noise. I am pretty sure its the crank pully or something, deffinatly one of the bottom two pullys, its wobbling and smacking the engine and horrible knocking. any ideas how to fix it? its a SWEET car other wise!

 

Start disassembling to see where the damage is.
IF really the crank start engine wiht no belts to be sure if it is the cranks.
PS DON'T RUN IT FOR TO LONG THIS WAY JUST TO CHECK YOUTHEORY.
How to fix?
You can tell better when disassembled the damage.

 

I hope your crank pulley isn't damaged!! Like Karl said, turn the pulleys one by one with the belt off to see which one has a wobble. Hopefully it's your smog pump or water pump...I figure those two are probably the easiest/cheapest to replace. Is your belt nice and tight? Is your belt tensioner operating properly? Sometimes the belt tensioners can get a little screwy, particularly if the spring is shot, or they're not mounted right...but that will usually make the belt slip or squeal.

 

If it IS your crank, by the way, perhaps your harmonic balancer is shot and counterbalancing the crank? If this is the case, you should notice vibration from the engine that gets progressively worse in higher rpms. Our balancers need to be neutrally balanced, because the cranks themselves are balanced, unlike, say, Ford 302's.

 

1985 model year is a multiple belt design.
By removing ALL belts, & just staring vehicle FOR SHORT TIME, you'll find out where the noise is from or see the trail.
My 1985 S-10 Blazer, the outter ring balancer came off in my hand! If ya need new one, find a good one in the yard & use a balancer repair sleeve for good results. Balancer repair sleeve is $4.
Due to age of the part & lack of maintneance, the rubber on these V-6 old balancers is usually shot & history cause of oil from leaks!
PS Don't go overboard investing money in this little 2.8 mill. They weren't meant to last forever which is why ya got a "deal!" Just patch & keep going til mill dies then injest a 3.4 for relaible upgraded power. This upgrade involves major cash for mill, swap & to rebuild eventaully the tranny, too.
Good luck with project. Again, keep cost down for your own enjoyment, elsewhere.
From one that knows.

 

Ohh, didn't even notice the year! Eep. Multiple belts suck...

 

As long as no problems it's quite acceptable.
I don't own a vehicle that is a serpetine belt set up & I hear they have their joys, also.

 

They're godawful easy to work with. And all it takes is a breaker bar on the belt tensioner to get the sucker off. Sure, there's the chance of it breaking and disabling the entire car...but how often do you see a serpentine belt break on a street car?

 

Ya know, it takes just once, it seems!
I see lots of things on sides of roads!
My favorite was the Union Ice House outfit, that I saw, grabbed and have been since using for my skiing outfit.
Bibs & Jacket Only missing parka!
What cold! AND WATER REPELLANT!
And it is my size!

I've only had one belt break on me on the road.
WAS A LONG TRIP HOME! Had to keep stopping to keep water temp down!

 

Multiple belts are a pain in the ***. serpetine belt systems are great and the rule of thumb is the same, don't let the belt(s) get old and crack, replace when needed. One thing that does happen with serpentine is the tension can get weak and the belt will squel even if the belt is new so thats an added expense of $20 to replace BUT you never have to worry about over tighting and wearing out the bearings in anything always perfect tesion. Also it will take you longer to open up the hood then to change a serpentine belt, real handy.