Sorry, I’ve been meaning to reply with info but many things came up. Heat cycling does work. My usual tech for removing stubborn bolts in order is;
1) Soak lead in threads (or in your case if you can get to the back – tail threads – drip it down the back of the pulley into the thread holes) in liquid wrench. Overnight.
2) For broken-stripped head bolts: ‘Mount’ the broken bolt remover – I use one that you drive on and it cuts a spline(Lisle) as you drive it on. I’ve seen the Sears removers and was interested, but didn’t like the fact that you could not work the bolt back and forth to help loosen it.
3) Heat up the pulley to ‘toasty’ warm.
4) Hit the back of the bolt ONLY with chip cooler (you are trying to shrink the bolt while having the heat expand the hole it is in). I don’t use Propane(it’s weak), use MAPP gas. Watch the amount of heat though. MAPP gas stands for “methylacetylene-propadiene propane” – note the Acetylene in the name. It is in yellow tanks. Just read that they discontinued production in 2008 8-( They now use LNG with high levels of propylene.
5) Apply torque (not with impact wrench – need smooth torque, not brute force) to loosen. You may need to work it back and forth, including after it breaks loose. May need to rinse-repeat, going back to #1 and repeating. Patience.
In your case, you might want to chase the threads with a tap after you remove the bolts. Remaining threadlock can cause problems because it may start rebonding when the engine gets hot. Watch out for ‘chips’ or debris. Best done with pulley off the vehicle.
If that is threadlock, it looks like the ‘blue’ one, which is not the highest strength (red), but it does look like it was literally soaked in it… unless that is caused by corrosion not threadlock – would need a real high res pic to know. Most threadlock softens with heat.
NOTE: Are the replacement bolts a min of grade 3? or are they HD non-grade bolts. Need min grade 3 there.
PLUG: If you need weird high torque bolts, ABABA QA in El Cahon is a good supply. There used to be a nice place in National city for odd bolts – I think it was called Frank’s Truck supply – Walk in the door and an inventory of 6-71(s) greets you. I don’t see it any more.
