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AD Harmonic Balancer/Pulley Excitement
I think God is trying to tell me to write about this because this issue has come up twice in the last two weeks or so. Two different scenarios that can make for a bad day, both concerning the Harmonic Balancer. The Harmonic Balancer is that 6 to 6-3/4 inch round, heavy part that is attached to the crankshaft. It has a Pulley on it that runs your Water Pump and Generator or Alternator. The idea is to "Balance" the engine laterally so the crankshaft isn't as stressed from all of the torque being placed on the back end of the engine. This is why we need something called a crossmember behind the transmission so we keep everything nice and aligned and balanced on that end. Added stresses are not good for the driveline so GM set their drive trains up in a balanced way. They determined a heavy machined Harmonic Balancer was their solution of choice for the front end of the engine. They also call these things Vibration Dampeners. The Harmonic part of the words means to dampen the vibration and this is done through the rubber component of the Harmonic Balancer. On our engines, the rubber part is just in front of the pulley and separates the pulley from the weighted part. Also in our case, the Balancer is riveted to the Pulley so they appear to be one piece. The Balancer is one of those parts you just forget about until something happens. So what could happen you ask?
Scenario One (from just a few weeks ago): You are hearing this loud clacking sound that sounds very much like valve chatter. You pull the fan belt to eliminate anything that could be causing it like Alternator Bearings, Water Pump, etc. and the sound goes away! This could lead you to believe the two aforementioned parts are causing it, but upon further inspection, you tug on the pulley of the Balancer and it is loose! That I know of, nobody sells rubber replacements for repairing the Balancer, and although it is possible to repair it by removing those rivets, replacing the rubber with just a similar piece of rubber and then using grade 8 bolts instead of rivets to put it back together, it is easier to find a replacement Harmonic Balancer.
Scenario Two (from last week): You are driving along when you hear a nasty grinding kerthunk sound and your water temperature skyrockets and your charging system quits. I can't believe he got away with no damage, but this happened to a friend of mine. The entire Harmonic Balancer just fell off! This is because it was not properly installed or it was too loose of a fit around the crankshaft snout. GM didn't bolt their Harmonic Balancers to the Crankshaft. They are merely a press fit. This can make for a disastrous situation and I have heard horror stories about this happening so I am very happy for my friend.
So what do we take away from this. When getting your 216/235/261 engines machined at the machine shop, have them drill the crankshaft for a 7/16" fine thread bolt that goes into the crank about an inch and a half. They can put the crankshaft on a Lathe to get that bolt hole in the dead center of the crankshaft. I paid about $60 the last time I was at the engine shop and it is money well spent. You can also do this yourself with a drill guide, hand drill and a 7/16" fine Tap, but I do not recommend it because the crankshaft is made out of some pretty solid steel and if you get an uneven push on the drill through that deep of a hole, the bolt will be loose inside the threads and possibly defeat the purpose. It is possible, but I tried it myself and that was the result.
Installing a Harmonic Balancer on an AD could not be simpler. And it doesn't matter if your paint job is pristine or not. All you have to do is honor what GM designed into your vehicle. You see that hole in the grille near the bottom and in the center of the grille? It is there for cranking your engine over with an engine crank! Your original engine had a special end on the balancer that accepted a special hand crank. Even the radiator is higher than that hole so nothing needs to be removed or moved out of the way. You simply get a 3/4 inch lead pipe about 4 feet long, add a threaded coupler to the end of it that you do not care about, then put a piece of oak against your harmonic balancer so you do not hit it directly. Ensure the key is in the keyway on the crankshaft, start the Balancer straight and then hit the end of the pipe with a large hammer. Once you see it move and it is starting properly, get out the Sledge Hammer because it will need to be set all the way in. You will definitely feel when it has bottomed out. Then go to the hardware store and get yourself another coupler because that one is beat too badly to use again! Any woodworker probably has a 3/4" pipe clamp that is 4 feet or so long, but where ever you get it, thanks to GM for giving us the hand crank hole in a case like this!
Before you put the Balancer back on, check the outside diameter of the crankshaft mating surface on the Balancer. Is there a groove worn into that surface? This is where the front main seal (located on the timing cover) rides and over time can wear a groove in the Balancer. This causes your front main seal to leak. That seal is also why we do not apply heat to the Balancer to make it go on smoother. If you have a groove or suspect oil leaks, the vendors carry a Speedi-Sleeve that goes over that surface and makes it like new again. Actually due to the thickness of the sleeve, a little better than new. They are made out of stainless steel and they are easy to install.
Further reading on the generic Harmonic Balancer is available here:
https://en.wikipedia.org/wiki/Harmonic_balancer
Winter is here so be sure you have your anti-freeze levels correct and your heater system working. Seeya Next Week!
I think God is trying to tell me to write about this because this issue has come up twice in the last two weeks or so. Two different scenarios that can make for a bad day, both concerning the Harmonic Balancer. The Harmonic Balancer is that 6 to 6-3/4 inch round, heavy part that is attached to the crankshaft. It has a Pulley on it that runs your Water Pump and Generator or Alternator. The idea is to "Balance" the engine laterally so the crankshaft isn't as stressed from all of the torque being placed on the back end of the engine. This is why we need something called a crossmember behind the transmission so we keep everything nice and aligned and balanced on that end. Added stresses are not good for the driveline so GM set their drive trains up in a balanced way. They determined a heavy machined Harmonic Balancer was their solution of choice for the front end of the engine. They also call these things Vibration Dampeners. The Harmonic part of the words means to dampen the vibration and this is done through the rubber component of the Harmonic Balancer. On our engines, the rubber part is just in front of the pulley and separates the pulley from the weighted part. Also in our case, the Balancer is riveted to the Pulley so they appear to be one piece. The Balancer is one of those parts you just forget about until something happens. So what could happen you ask?
Scenario One (from just a few weeks ago): You are hearing this loud clacking sound that sounds very much like valve chatter. You pull the fan belt to eliminate anything that could be causing it like Alternator Bearings, Water Pump, etc. and the sound goes away! This could lead you to believe the two aforementioned parts are causing it, but upon further inspection, you tug on the pulley of the Balancer and it is loose! That I know of, nobody sells rubber replacements for repairing the Balancer, and although it is possible to repair it by removing those rivets, replacing the rubber with just a similar piece of rubber and then using grade 8 bolts instead of rivets to put it back together, it is easier to find a replacement Harmonic Balancer.
Scenario Two (from last week): You are driving along when you hear a nasty grinding kerthunk sound and your water temperature skyrockets and your charging system quits. I can't believe he got away with no damage, but this happened to a friend of mine. The entire Harmonic Balancer just fell off! This is because it was not properly installed or it was too loose of a fit around the crankshaft snout. GM didn't bolt their Harmonic Balancers to the Crankshaft. They are merely a press fit. This can make for a disastrous situation and I have heard horror stories about this happening so I am very happy for my friend.
So what do we take away from this. When getting your 216/235/261 engines machined at the machine shop, have them drill the crankshaft for a 7/16" fine thread bolt that goes into the crank about an inch and a half. They can put the crankshaft on a Lathe to get that bolt hole in the dead center of the crankshaft. I paid about $60 the last time I was at the engine shop and it is money well spent. You can also do this yourself with a drill guide, hand drill and a 7/16" fine Tap, but I do not recommend it because the crankshaft is made out of some pretty solid steel and if you get an uneven push on the drill through that deep of a hole, the bolt will be loose inside the threads and possibly defeat the purpose. It is possible, but I tried it myself and that was the result.
Installing a Harmonic Balancer on an AD could not be simpler. And it doesn't matter if your paint job is pristine or not. All you have to do is honor what GM designed into your vehicle. You see that hole in the grille near the bottom and in the center of the grille? It is there for cranking your engine over with an engine crank! Your original engine had a special end on the balancer that accepted a special hand crank. Even the radiator is higher than that hole so nothing needs to be removed or moved out of the way. You simply get a 3/4 inch lead pipe about 4 feet long, add a threaded coupler to the end of it that you do not care about, then put a piece of oak against your harmonic balancer so you do not hit it directly. Ensure the key is in the keyway on the crankshaft, start the Balancer straight and then hit the end of the pipe with a large hammer. Once you see it move and it is starting properly, get out the Sledge Hammer because it will need to be set all the way in. You will definitely feel when it has bottomed out. Then go to the hardware store and get yourself another coupler because that one is beat too badly to use again! Any woodworker probably has a 3/4" pipe clamp that is 4 feet or so long, but where ever you get it, thanks to GM for giving us the hand crank hole in a case like this!
Before you put the Balancer back on, check the outside diameter of the crankshaft mating surface on the Balancer. Is there a groove worn into that surface? This is where the front main seal (located on the timing cover) rides and over time can wear a groove in the Balancer. This causes your front main seal to leak. That seal is also why we do not apply heat to the Balancer to make it go on smoother. If you have a groove or suspect oil leaks, the vendors carry a Speedi-Sleeve that goes over that surface and makes it like new again. Actually due to the thickness of the sleeve, a little better than new. They are made out of stainless steel and they are easy to install.
Further reading on the generic Harmonic Balancer is available here:
https://en.wikipedia.org/wiki/Harmonic_balancer
Winter is here so be sure you have your anti-freeze levels correct and your heater system working. Seeya Next Week!