Removing Press Fit Wrist Pin

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Turbo360

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I have a 1995 C1500 with a 4.3 V6 that spun a rod bearing on #5. I tore the engine down, had the block inspected and cleaned and have started putting it back together and am now at the point of installing piston and rod assemblies. I'm aiming for a simple bottom end rebuild so I am re-using the pistons as they are still in good shape.

The rod on #5 was no good, so I bought a reman unit to swap over, but I can't seem to get the wrist pin out of the old rod for the life of me. I understand this is best left to a machine shop, however I'm trying to save where I can, but the bigger problem is that I already have the crank and cam in with assembly lube so I'm on the clock to finish assembly and get it started while the lube is still able to do it's job on initial startup. My local machine shop does good work, but they are not very fast and would take a few days or better to make the swap themselves.

I tried using a propane torch (the same kind you can screw the small MAP cans to) to heat the rod end around the wrist pin for a few minutes before trying to tap the pin out, but it isn't moving. Those that talk about doing it at home this way say to heat the rod end up long enough to get hot, but stop before it gets red hot which I did.

Have you guys experienced this before? What would you do differently?
 

rebelyell

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I have a 1995 C1500 with a 4.3 V6 that spun a rod bearing on #5. I tore the engine down, had the block inspected and cleaned and have started putting it back together and am now at the point of installing piston and rod assemblies. I'm aiming for a simple bottom end rebuild so I am re-using the pistons as they are still in good shape.

The rod on #5 was no good, so I bought a reman unit to swap over, but I can't seem to get the wrist pin out of the old rod for the life of me. I understand this is best left to a machine shop, however I'm trying to save where I can, but the bigger problem is that I already have the crank and cam in with assembly lube so I'm on the clock to finish assembly and get it started while the lube is still able to do it's job on initial startup. My local machine shop does good work, but they are not very fast and would take a few days or better to make the swap themselves.

I tried using a propane torch (the same kind you can screw the small MAP cans to) to heat the rod end around the wrist pin for a few minutes before trying to tap the pin out, but it isn't moving. Those that talk about doing it at home this way say to heat the rod end up long enough to get hot, but stop before it gets red hot which I did.

Have you guys experienced this before? What would you do differently?

there's a good reason they're called "press fit" ... and it'll show some color before applying pressure.
Plenty pistons wrecked because of bad technique ... suggest pay a pro with correct equipment & chops.
Real Shops' rod heaters are either gas-fired or electric-induction ... maybe go take a look?
 

Turbo360

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I would take it somewhere, but time just doesn't allow. The machine shop local to me would take too long to make the swap.
 

PlayingWithTBI

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I would take it somewhere, but time just doesn't allow. The machine shop local to me would take too long to make the swap.
You gotta think - "do I have time to order a new piston and have it pressed on after I waste time trying to get this ***** off"?
 

NickTransmissions

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What would you do differently?
I'd take your con-rod assemblies to a competent machine shop and have them R&R the piston wrist pin...Otherwise you'll need a special fixture and press pin tooling, sold by SPX under the 'Kent Moore' brand name, along with a shop press, to do the removal and reinstall yourself.
 
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0xDEADBEEF

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I have done it with a harbor freight shop press, map torch, and some "custom" wood blocks. I wouldn't even consider it without a press. I think the press was $100 and I have gotten a lot of use out of it, but that was like 15 years ago.
 

95burban

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my local machine shop charges 15 a rod/piston.

If you press it out support it good so you don’t damage or crack the piston.
 

Schurkey

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There are NO guarantees that a piston pin removal will leave a usable piston. Your odds are better with an experienced machine shop, but even then a damaged piston is still possible.

1. If the piston pin--press-fit in the rod--is galled on the way out of the rod, it's going to score the piston pin hole as the damaged pin is forced through.

2. If the piston isn't supported properly, you'll distort the piston from the force of the press used to shove the pin out of the rod.

3. By the time you torch the rod hot enough to expand the press-fit, there's a good chance you'll have melted the aluminum of the piston; or if not melted, heated enough to affect the hardening of the aluminum. You're not going to accomplish this with Propane, or MAP-Pro unless you're adding oxygen also. You need to get the rod HOT, QUICKLY, before the piston has enough time to absorb heat and melt.

Take the piston and rod to a machine shop, pay them to do this.

Or hit up eBay, and buy the special Kent-Moore tooling. I did. The Kent-Moore tooling allows the piston to float free--no press pressure on the piston, because the tooling supports the rod directly. But if the pin gets damaged as it's pushed out, it's still going to score the piston pin hole.
 

rebelyell

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I would take it somewhere, but time just doesn't allow. The machine shop local to me would take too long to make the swap.
Are you isolated between the bitterroot & the frank church? There is no magic trick here
No matter what: with your hat in hand & head bowed, go back to the shopowner and beg forgiveness for whatever he thinks ya did ... please sir, I promise on old yellers soul etc etc etc ........... either that or load up and spend more money & time up the road. The job takes a pro well under 1/2 hour.
 

Sean Buick 76

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Yes use a machine shop, plus you will need to press the pin back in with the new rod. Are you using a new crank or did you have it machined after spinning the bearing?
 
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