Badly stuck expansion valve bolts - Dodge Grand Caravan

[Diametric]

I'm dealing with the problem of expansion valve bolts that do not want to let go.
There must be a good bit of corrosion on the tips of the threads that were inside the evap housing.
They will turn about 4 turns then lock up solid.

I sprayed them with PB Blaster and right now I'm waiting 1/2 hour to go try again.
If that fails I think I'm faced with drilling the heads off so I can remove the expansion valve then try to get the remaining studs out.

I think the evap core is good (I'll pressure test it) so I was gonna re use it but if the evap core threads strip it's a fairly involved job to remove the dash to replace the evap. Trying to avoid that.

Any trade tips on getting these boogers out?

If so, thanks!

[JohnHere]

Can you get in there with an oxy-acetylene torch (#1 tip or smaller) to heat-up the ends of the studs cherry red? If so, the nuts will come right off. Better wash off all the PB Blaster, though, and have a fire extinguisher ready.

[Diametric]

Can you get in there with an oxy-acetylene torch (#1 tip or smaller) to heat-up the ends of the studs cherry red? If so, the nuts will come right off. Better wash off all the PB Blaster, though, and have a fire extinguisher ready.

Hello JohnHere!

No sir. There is no access to the bolts tips. Maybe if I removed the entire dash assembly I could get to them from the inside of the vehicle. But I'm really wanting to avoid that if possible.

I don't think there are any nuts. AFAIK, the bolts thread directly into the evap core on the other side of the firewall.
So it must be the last three or four threads of the bolts that were exposed to moisture inside the evap housing that corroded and it's that small 3 or 4 threads that are jamming when trying to unscrew them.

I was also thinking that IF I drilled the heads of the bolts off, I could then move the expansion valve out of the way and that just might allow me to heat the bolts with a torch a bit. Still not sure that would do the trick. At least I could get better access to the bolt threads and keep soaking them with PB Blaster then turning them back and forth hoping to eventually free them.

Worst case scenario...I have to remove the entire dash assembly, steering column, mirrors and all the dash fascias and take the dash out then remove the entire HVAC assembly to put a new evap core in there. Tedious but if I have to I will. One of the most tedious things about removing Gen 4 Dodge Caravan dash assemblies is that everything is held together with the most brittle plastic I've ever seen. Trying to unscrew trim screws almost always means breaking off the entire screw stanchion. The trim and fascia parts end up with so many broken pieces that screwing the assemblies back together and reinstallation is near impossible. It is very common when I take these dash assemblies on the older Dodge Caravans apart that I spend one or two days just rebuilding the posts and screw stanchions or cracks in the HVAC face plate assembly. Super brittle. The good news is that once I have done this rebuilding process they usually never break up again. I have 5 Dodge Caravans. All Gen 3 or Gen 4. If you have any kind of Dodge or Chrysler vehicle you probably know exactly what I'm taking about.

These are my thoughts anyway.

[Cusser]

I'm dealing with the problem of expansion valve bolts that do not want to let go.
There must be a good bit of corrosion on the tips of the threads that were inside the evap housing.
They will turn about 4 turns then lock up solid.

I sprayed them with PB Blaster and right now I'm waiting 1/2 hour to go try again.

Since you can turn about four turns, I'd keep trying the PB Blaster and turning through those 4 turns, then more Blaster. That's what I'd do, and be patient...

[Diametric]

I'm dealing with the problem of expansion valve bolts that do not want to let go.
There must be a good bit of corrosion on the tips of the threads that were inside the evap housing.
They will turn about 4 turns then lock up solid.

I sprayed them with PB Blaster and right now I'm waiting 1/2 hour to go try again.

Since you can turn about four turns, I'd keep trying the PB Blaster and turning through those 4 turns, then more Blaster. That's what I'd do, and be patient...

Thank you Cusser.
Good advice.
I only hope the torx slot on the bolt head holds up. It seems to be slowly rounding out. Once the tool can no longer get a good bite I think at that point I'll have no choice but to drill.

If I end up going that route, do you think applying heat to the remaining stud would make any difference?

[Diametric]

Well, my patience ran out, and the torx slot started wollering out.
After trying to work the bolts back and forth for about an hour, applying PB Blaster along the way, and getting nowhere I decided to drill the heads off the bolts.

I can tell you that trying to do that with HarborFreight Titanium drill bits doesn't cut it. I can give the Titanium bits an honorable mention against the grade 8 or grade 10 hardened bolts, but they were definitely not up to the task.

Fortunately, I also had a set of HarborFreight Cobalt bits and alas, they made quick work of those same bolt heads. It really is an amazing difference.

So with both bolts decapitated......I still can't get the expansion valve off (yet). Not sure what's holding it? It wiggles and moves and has about 1/4 inch gap between the mounting block and the Exp Valve, but it just won't let go and slide out. I kept thinking it was a small bit of the head of one (or both) bolts still hanging on just enough to keep it from coming off, but no matter how much more I drill the bolt studs....no go.

I can't say this job is a whole lotta fun at this point.

ExpansionValveDrillOut_IMG_20260822_155424201.jpg (78.32 KiB) Viewed 45 times

In the photo below, you can make out (barely) the remaining stud of the now decapitated bolts. Bad angle. I'll try to get another better shot and post it.

ExpansionValveDrillOut_IMG_20260822_162016467.jpg (113.16 KiB) Viewed 45 times

I'm going out now to get a small diameter punch and play Whack a Mole with those decapitated studs to see if I can get them to let go.

[Diametric]

Anyone else see that strange looking section of hose next to 2332 in the photo above?
I need to investigate that. I wonder if that could be a defective hose that is collapsing under vacuum or just an optical illusion?