The Stovebolt Site Forums The Shop Area Engine Shop loose crank pulley/balancer

Howdy people,

I had a 235 built for me a couple years ago, only have maybe 350 miles on it now. I was tinkering around with it to find the crank pulley/balancer turns on the end of the shaft...I find this very odd. It turns only 1/4 - 1/2" and stops. it doesn't wobble though.

I'm guessing there is a key that stops it from spinning/turning all the way around. What's the deal with this ???

Travis Weedman
Waitsburg Wa

It's possible that the rubber damper is shot.Does the whole pully turn or just the outside?Don't drive it till you find the problem,I've seen em trash the whole rad, and other stuff up there.

Howdy Travis,

Sounds like you've got a bit of a problem! The balancer on a 235 is pressed on (often with a big hammer) and shouldn't have any movement. The key serves as an alignment guide and so that it won't rotate on the crank snout. You shouldn't have any "play" at all!!! The good news is that you've discovered it before it came off and damaged the fan and radiator and the bad news is that there's no quick and easy way to fix it.

The fix: The very simplest fix, if there's no damage to the keyway (unlikely) is to drill and tap the crankshaft and install a Small Block Chevy Harmonic balancer bolt/washer to tighten up the balancer. However, this requires pulling the radiator and possibly some front sheetmetal to gain access. If your balancer outer ring is broken loose, or your keyway wallowed out, it's time for a replacement balancer.

Drilling the crank for the SBC bolt is not as scary as it sounds and is well worth the effort. By drilling and tapping the crank, you can "draw" the balancer down tight and insure it won't come off until you remove the bolt and use a puller.

You're fortunate to have found it before it came off....although you can't detect a wobble it is obviously loose on the snout and your going to have to undertake a labor-intensive repair. On the brighter side....you aren't stranded along the highway with a lot of damaged, expensive parts, and still have to follow the same procedure.

Sorry that I didn't have some better news for you...

Dave

BTW....you'll want to change out the timing cover seal while you've got it all broken down.

Grub and Dave, thank you for the reply, it appears the unit as a whole is moving on the shaft, I can't move it on or off by hand but I can move it around by hand. I'll remove the radiator and fan etc and take a look at it. I have another engine in the shed with the balancer on it...could I take that one and see how tight it is? Or would it be just a waste of time?

I did a search for this issue on here and read that a letter "w" bit is the correct size for a 7/16-20 thread.

I am very surprised this happened...but then again the mech that built this engine has not always been totally honest with me on other projects

Thank you again for the reply.

Travis -

I ran into this problem with my 261 about four years ago. Same issue. The balancer would move back and forth when the engine was off. Mine actually made a clunking noise. That's how I found out I had a problem.

I would do what I did - pull the balancer and find another to put on. I wouldn't mess with the hole drilling and tapping. It might not fix the problem. If you have another balancer, I would not waste a minute trying to make the one you have work. The end result may not be what you are wanting and it could still fail on you. I would put on one that works like it is supposed to and nothing short of that.

Send the broken one to a balancer repair place, let them fix it and keep it for a spare.

Just my opinion.

Joe

Drilling and tapping the crank for a SBC bolt is one of several minor operations that make working on a 216/235/261 a whole lot easier. By drilling/tapping the crank, you can use a stud/washer combo to DRAW the H/B into proper position, replace stud with SBC bolt and large washer and insure that it will remain secure. Retire the BFH!

Secondly, changing out the 2 lower timing cover bolts so that you don't have to drop the pan to remove the timing cover is, in my estimation, worth the time and effort. Drilling the lower cover/block holes to 3/8" (liberal application of grease will catch chips)and threading the holes in the front main cap (removed from the engine) will eliminate pulling the pan to access the 2 lower timing cover bolts. You can get to all the timing cover bolts from the outside. It allows you to loosen/tighten the timing cover without pulling the oil pan. This helps insure that when installing the balancer, that the loose cover allows the seal to center itself on the H/B seal surface, reducing the chances for oil leaks.

As long as you are going through all the effort of pulling the sheetmetal to correct the balancer issue, it just seems to me that insuring that you aren't going to have to repeat the operation again, makes sense. This would especially hold true if there was some issues with the crank snout. An H/B with a bolt is not going to do any walking.....period! As with any operation on your own vehicle, it's your call. Just thought you might be open to some options.

Dave

If you are swapping balancers take a close look at the replacement as car balancers have a bigger diameter pulley affecting belt length and water pump/generator speed. A few minutes on a hotplate and it should slip right on without a hammer or bolt to pull it on. Good luck.

Curt B.