NEED HELP Best way to lock flywheel for harmonic balancer replacement.

Timber531

Member
Won't take much time, replacing harmonic balancer on my 4.2l 04 envoy 205k mi and keep hitting road blocks, mainly having to repeatedly buy/rent special flower tools/parts.

Either way, got down to removing the HB bolt and now I'm conflicted on how to remove it. I've heard jamming a prybar into the flywheel can work or grind the sh** outta your flywheel teeth.

Also seen where there is a hole in what I thought was the timing cover/oil pan? (I havent looked for the holes location under the envoy) with a 15mm deep socket w breaker and go that direction.


Or should I just leave that alone and go buy an air impact gun 1000lbs+?


Hopefully I can get a response today! First post luck mode engaged 👍🏻 Any other tips would be appreciated, and I have read several threads on HB replacement but didn't quite find what I was looking for, maybe I overlooked a few things, but lmk if you need any info or pics and I'll post em asap! Thanks.
 

TollKeeper

Gold Supporter
I got my harmonic balancer bolt off with a Electric Craftsman Impact, and again with a Electric Rigid impact.

There are flywheel holder tools on the market. But I do not know if any of them have ever been designed for the 4.2.

There are specific tools for a flywheel holder, but they are expensive (160-300).

I dont know if a tool for the LS engines would work on this engine or not.

See if this thread helps you any..
 
OP
T

Timber531

Member
Yeah I recently checked out that thread too but it's getting to the point to where I'm just going to go down to harbour freight and see what I can get. Worst case scenario I get an impact and return It. But I was just kind of messing with it and the crank seems to turn way too easy with crank pulley bolt still Torqued down. I have the fan clutch and Fan/shroud removed the belt was still on but The engine seemed to turn a lot easier than I would have expected. Thanks for your advice greatly appreciated
 

TollKeeper

Gold Supporter
I was able to turn the crank bolt by hand with only a 3/8 ratchet. Its not until you get into really high compression, or diesels, that it would get hard, at least in my opinion.
 
OP
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Timber531

Member
I got my harmonic balancer bolt off with a Electric Craftsman Impact, and again with a Electric Rigid impact.

There are flywheel holder tools on the market. But I do not know if any of them have ever been designed for the 4.2.

There are specific tools for a flywheel holder, but they are expensive (160-300).

I dont know if a tool for the LS engines would work on this engine or not.

See if this thread helps you any..
 

TollKeeper

Gold Supporter
Link no workie
 

TollKeeper

Gold Supporter
I really dont have a recommendation for a impact. I like my Craftsman, and has served its purpose for MANY years. The Rigid has more power, but runs off a chuck, and being a impact, on a 1/2 inch socket.. The chuck shatters.

The newest to the market has been the Milwaukee, and has seen many praises for power, reliability.. But costs a pretty penny. They cost 250 without a battery or charger.

The next one is from Harbor Freight, Earthquake XT. Not a lot of reviews out there on them, other than the ones on the Harbor Freight website. My shop uses these to wrenching on Tractor Trailers. They do the job. They are also 280 bucks!
 

TollKeeper

Gold Supporter
You might peruse thru this thread, some talk about impacts..
 
OP
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Timber531

Member
Awsome, greatly appreciated TollKeeper. I don't have a whole lot of money left over to spend, good thing my arm wore out before I could throw any more money at this engine.

And my neighbor came by to check out where I was at and he had mentioned it was easy to turn.
He knows a good bit about engines but never worked on Vortech 4200. I had my 24MM socket and a decent sized breaker bar but I doubt there would be much difficulty trying to use 3/8 ratchet by hand.
I don't have anything on before throttle body and fan clutch etc is all removed plus Front end is jacked up, I'm not sure if that Has any correlation to crank turning.

Im going to check that thread out now, I'm doubtful but hopefully I can find something at harbor freight or even home depot that can fit to why I don't have to remove the radiator. Afterwards I'll post how it goes. If you have any other tips or advice, I'll take any of it lol, thanks again toll.
 

TollKeeper

Gold Supporter
If you are on a strict budget (arent we all LOL).. Dont forget to shop pawn shops. Thats where I bought my Craftsman, new in the box, for 1/3 of the price of new at sears.
 

MRRSM

Lifetime VIP Supporter
The Most Direct Way to Restrain the Crankshaft if THE ENGINE IS INSTALLED IN THE SUV is to locate the Black Plastic Plug centered along the lower Oil Pan aft section adjacent the Center Flywheel Access Port for the Removal and Installation all of the Three Torque Converter Bolts (separated by 120 Degrees). After removing the Black Plastic Plug shown below, Rotate any one of those Three Torque Converter Bolts around in a Clockwise Motion until one TC Bolt Head can clearly be seen through the Hole leading through the back of the Crank-Case Oil Pan. Then, Insert a 15mm Deep Socket through that Hole over the TC Bolt Head with the Socket attached to a 1/2" Breaker Bar and rest the Bar Handle on the Ground so that the Flex-Plate (and thus the Crankshaft) CANNOT Turn in ANY Direction during the Crankshaft Bolt R&R Procedures.

You should avoid using an Impact Gun when removing the Crankshaft Bolt on any Atlas Vortec Engine if possible. Please opt instead for using an Impact Grade 1/2" Drive Socket sized for the Crankshaft Bolt Head along with a 1/2" Breaker Bar aided with a 1.5" Steel Water Pipe for leverage and SLOWLY unwind the Crankshaft Bolt Counter-Clockwise. Discard that Bolt. Obtain a Brand New One from either eBay or gmpartsdirect.com.The Old Harmonic Balancer will require replacing the Old GM Part# 12578073 Sealing Friction Washer (Placed upon the INSIDE of the Harmonic Balancer Center Snout) or by getting a New Harmonic Balancer Kit as GM GENUINE Part# 12578069 (This Kit Includes the GM Part# 12578073 WASHER) and requires the Seal Kit Part# 89017622).

K&M Part# EN-48034 Harmonic Balancer Installation Tool Kit will be required to get the Harmonic Balancer installed onto the Crankshaft PRIOR to installing a Brand New Bolt. Do NOT attempt to use either the Old or New HB Bolt to get the HB installed as it will Damage the Threads and Ruin the Crankshaft.

In the case where the Engine is Mounted on an Engine Stand, you should pull out the Black Plastic Plug and Pass a Large Bolt through that location and fasten a Nut and Washer Combination in between the Hole through Flex-Plate where it aligns with the Hole through the Oil-Pan when the #1 Cylinder is positioned at Top Dead Center (TDC) AND the Small Timing Circle on the Crankshaft Cog is at the 4-5 O'clock Position. Tighten them together GENTLY and snugly enough so as NOT to Damage either the Aluminum Crankcase OR Warp the Flex-Plate.

This action will prevent the Flex-Plate (and thus... the Crankshaft) from Rotating either Clockwise or Counter-Clockwise during the TTY Crankshaft Bolt Tightening Sequence. These images show where that Oil-Pan Port Black Plastic Plug is located. Please remember to Remove the Bolt, Nut and Washer Restraining Combo as soon as the Crankshaft Bolt TTY work is completed as follows:

After properly performing the Installation of the Harmonic Balancer:

(A) Purchase a Brand New GM Part# 11609792 TTY HB Bolt from eBay or gmpartsdirect.com

(B) After first restraining the Flex-Plateas per the above, Tighten the New HB TTY Bolt into the Crankshaft Snout and use 110 Foot Pounds of Torque on the First Pass.

(C) Then PAINT A WHITE VERTICAL REFERENCE LINE ON THE BOLT FACE that crosses onto the adjacent upper Timing Cover. Then, using a ½” Deep Socket and a ½” Breaker Bar to Rotate the TTY Crankshaft Bolt another 180 Degrees (FROM the 12:00 position TO the 6:00 position in a Clockwise Direction) to achieve the Final TTY …and STOP.
 

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