Badly stuck expansion valve bolts - Dodge Grand Caravan

[JohnHere]

So glad that you were finally able to remove the TXV--after days of work, I'm sure. Been there, done that...although not for this particular vehicle.

We're always interested in how our members solve MVAC problems, regardless of whether we have the same vehicle.

On to the next time consuming, difficult job: Replacing the evaporator.

About the TXV bolts, I would try to get stainless steel, although you'll still have the dissimilar-metals problem. To help overcome that, I suggest coating the bolts and threads, in addition to all the o-rings and joints, with Nylog Blue.

[Diametric]

So glad that you were finally able to remove the TXV--after days of work, I'm sure. Been there, done that...although not for this particular vehicle.

We're always interested in how our members solve MVAC problems, regardless of whether we have the same vehicle.

On to the next time consuming, difficult job: Replacing the evaporator.

About the TXV bolts, I would try to get stainless steel, although you'll still have the dissimilar-metals problem. To help overcome that, I suggest coating the bolts and threads, in addition to all the o-rings and joints, with Nylog Blue.

Thank you sir!
You're right. Good advice.

I'm not familiar with Nylog Blue but will now check into it and likely get it. Thanks for that.

Follow up:
A bit of research suggests that NyLog Blue would not be good for anti-corrosion protection on bolts?

[Diametric]

A note to Cusser.......

When I looked closely at the tips of the two bolts that I could not remove, it seems that there was more deformation of the threads than corrosion on them. Obviously some rust revealed by the rust stains on the back side of the attaching plate. That rust made it impossible to remove them. But after my initial and subsequent attempts to force the bolts out I guess the friction removed the corrosion while damaging the threads at the same time.

Once the threads are deformed it doesn't matter how patient one is, they simply are not coming out without damaging the threads of the device they pass through, right? I'm pretty sure that if I had continued with the force I would have either fully stripped the threads out of the aluminum attaching block, making it difficult to reuse, likely requiring a new one or the bolts may have snapped.

So, the process you suggested may have worked BEFORE I tried unscrewing the bolts as far as I could (thus deforming the threads) ?
Meaning, if someone runs into this situation it's important to try to get PB Blaster on the exposed tip but only gently try to remove the bolt simply to dislodge corrosion or buildup using the procedure you described previously. Not wrenching on it hard to see how far it will go before it jams up completely like I did at first.

If I run into this again, I'll try your procedure again but next time without trying to see how far the bolts will come out, applying force (which will surely deform the threads on the tips of the bolts). A bit odd because the bolts are very hard steel and the item they are screwed into is softer aluminum. Still, the threads on the bolts were damaged.

I'm discussing this for the benefit of others who may run into this same problem to give them more information to consider. I hope it helps someone and thanks for your good advice. Stuck Expansion Valve bolts are no joke.

TMI?

[Tim]

Good post.

Did you ever apply heat to the bolt area?

[JohnHere]

To ensure a leak-free system, I use Nylog Blue on every o-ring, threaded connection, Schrader valve, Schrader valve cap seals, etc. "A little dab will do ya."

[JohnHere]

Follow up:
A bit of research suggests that NyLog Blue would not be good for anti-corrosion protection on bolts?

Nylog Blue (NB) is formulated from a blend of very thick, extremely sticky refrigeration oils that hang on tight and don't harden. It's compatible with R-134a and R-1234yf (Nylog Red is used for older R-12 systems). So if some NB finds its way into a modern MVAC system, it will do no harm. Using anything else having a hydrocarbon base risks contaminating the system with incompatible substances. When applied to bolt threads (or to the entire bolt) as an anti-corrosion protectant, it prevents binding and seizing, making future disassembly easier. I use it all the time for the purpose you mentioned, and for sealing entire MVAC systems (o-rings, threaded joints, etc.). It's good stuff.