Mistral Rebuild

[kworkman]

This one will most likely be coming in to Bryan but wanted some thoughts first. I bought a nice Mistral the other week and from the outside it is in great shape. I figured I could handle the rebuild since I've heard they are the easiest to overhaul. There was some salt corrosion on the inside but it didnt look that bad. Well because of that I cannot remove the retainer nut for the body. I figured if I remove the lever plate and mistral nozzel, I can put a large socket on there and help with leverage. Well the mistral nozzel wont budge either and also appears to be cross threaded in the body. Where do I go from here?

[SurfLung]

- Be careful of the nozzle. I twisted one right off putting too much muscle into it. They're made of brass. Fortunately, I could get a new one from VDH. But removing the remnants of the old one was tricky.
- As for the nut holding the body to the can... So far I haven't had one that was stuck too bad.

[swimjim]

PB Blaster penetrating oil is your best friend. Give the affected parts a good dousing and revisit the next day. Remember, these critters are made out of brass and they will only take so much. If we we're closer I'd walk you through it. Been down that road many a time.

Jim

[kworkman]

What about carberator cleaner? Ive got that and some brake cleaner in the garage.

[antique diver]

I'd take SwimJim's suggestion about the penetrating oil before I tried again to back it out. It's made for this kind of situation. Sometimes heat helps since the metal parts expand and contract, which can help loosen the threads. I wouldn't recommend putting too much torque since the small brass part can break more easily than you might think.

Having learned this the hard way, it sometimes is better to leave things in place than to risk breaking it off. If that happens it is really tricky to drill and tap out without some serious damage to the body.

Good luck, and let us know your results.

[Herman]

I'd take SwimJim's suggestion about the penetrating oil before I tried again to back it out. It's made for this kind of situation. Sometimes heat helps since the metal parts expand and contract, which can help loosen the threads. I wouldn't recommend putting too much torque since the small brass part can break more easily than you might think.

Having learned this the hard way, it sometimes is better to leave things in place than to risk breaking it off. If that happens it is really tricky to drill and tap out without some serious damage to the body.Good luck, and let us know your results.

The biggest thing to avoid is not making the situation worse once you have broken it. With the right equipment and knowledge it's not too hard to repair but if it's boogered up in an attempt to remove it without the right tools it can make matters a lot worse...in other words, if you break it off, find someone who knows how to deal with the broken part rather than attempting it with a hand drill and an easyout. In the end it will be a lot cheaper.

[kworkman]

I'll add some pictures.

[captain]

I have used heat from a propane torch to loosen frozen bonnet nuts on old corroded valves and regulators many times. It will not cause damage if done correctly. I heat the part slowly and every 15 seconds or so remove the flame and spray with some type of penetrating oil, I use Aero Koil. You want to heat it to the point where the penetrate will ignite when sprayed on the part without the torch flame present. At that point stop heating with the torch and use the penetrate to cool the part down and try to unscrew it. If it is still tight go through the procedure again. I have never had a case where I could not get it apart using this procedure. Don't worry about the rubber parts, you will be replacing them. Also use 6 point sockets and wrenches when working on frozen parts to prevent rounding off the wrench flats.

[Herman]

I would suggest you remove the oring that seals the pin before heating it. It's a lot easier to get out now than if it turns into a gooy mess with heat and oil on it.

[kworkman]

Well I got the retaining nut off after getting at it with PB Blaster. Im still working on the nozzel.

[kworkman]

Should I avoid using CLR to clean these parts? Or shoukd I jusy go with the SaltX that everyone talks about.

[Herman]

I few minutes soak in a 50/50 mix of white vinegar and water works well for me followed by a scrub with dish detergent.

[kworkman]

What do you use to scrub? Also, how do you get the labels clean without damaging the paint?

[captain]

I would suggest you remove the oring that seals the pin before heating it. It's a lot easier to get out now than if it turns into a gooy mess with heat and oil on it.

I have found that the amount of heat I apply does not affect o rings or valve seats to the extent of melting or burning them.

[kworkman]

Here is my progress so far.










Unfortunately I lost some chrome but I'm not concerned. Most of it will be hidden and I can always get it refinished some day. I figure I only dive fresh water and if the gaskets are good, water shouldn't get in the first stage anyway.