280z expansion valve

[Dave WM]

I picked a used evap/expansion chamber from a junk yard. The system had been open for a while as there was rust on the hi pressure switch, and junk in the expansion valve inlet. I removed the valve from its body, and flushed the evap with cleaner. This is the setup that has 3 separate cooling coils, all feed from the evap valve body (3 small and 3 large tubes).


Anyway in my zeal to clean the rust out I removed the brass fitting inside the inlet of the valve, got the spring out (covered in rust) soaked it in evap o rust. cleaned the area around where the spring rest with some q tips. Not sure how much more it can be disassembled to get access what I presume is a needle valve arrangement.

Anyway now the problem I foolishly did not measure (or count turns) before removing the brass spring retaining nut. I ended up guessing by looking how far the spring can collapse and then turning the brass retainer enough to about 1/2 that much.


IF any one has one of the types of expansion valves (look in side and you will see a sloted brass disk with a hole in the center. Please give me a measurement from the top of the inlet to the brass disk. I will get some pics later to better illustrate.

[Dave WM]

I made a rather long video that will be posted later tonight. Bottom line is I have the top of the brass spring retaining nut approx. 12.5 mm up from the base of the flare fitting connection to the plate that is bolted to the canister on the evap unit.

This was done after measuring the distance on another exp valve (but later think for a ZX). It was not the same pn it has a longer inlet snout but I took that into consideration. The new ZX unit has the top of the brass retainer about 12-13 mm up from the plate, so I used that as a ref. It looks right from what I recall of how many threads were showing before I disassemble it. (thread showing above the brass retainer that is).

[Dave WM]

pics

[Dave WM]

 

[hr369]

I don't have a caliper like yours but i think  counting the threads would just as accurate.  I counted 5 threads and its adjusted down to be right on the top of the 6th thread.

After setting the valve, set it in the freezer for half an hour and see if its closing correctly. 

 

You can pick up another used one on ebay but they usually sell em attached to the evap's. If you plan on having a/c for a long time, its good to have an extra.

Edited June 10, 2016 by hr369

[Dave WM]

I used your photo, that is exactly 9mm down. I tried the freezer test, I could not tell any diff in the air flow when blowing thru it between 77f (room temp) and 0f (freezer), at least not real noticeable. I am going to try it with the new one as well.

Ok update, the new one responds to the freezer (will shut down completely) the old one seems to have no effect, so that's it, old one is toast, I suppose its either lost its charge or there is something (rust) that is not allowing it to close up.

I found an old thread on this same deal, turns out guy had same thoughts about trying to disable (wide open) the stock TVX and install one up stream, even got into the same 90 degree bend issue. Since this is just a spare part I happened on, will just forget it for now. Its not in my nature to quit on something but this is a long shot to impossible to repair (the tvx).

I will conduct a few more experiments, like drawing a vacuum on both thru the inlet just to compare, just some fun stuff to do.

 

Edited June 10, 2016 by Dave WM

[Dave WM]

hmmm that was interesting (have video will post later) on the deep cycle vacuum pump the old one at 1st did not seem to be effected by cooling with dust off liquid. smacked it a few times on the side of a wood bench and it seemed to come alive, Not as vigorous as the new one but it did def react. Maybe the charge is ok and what the real problem is more rust at the valve needle.

[Dave WM]

more testing

 

[hr369]

Do you have an ultrasonic cleaner?  You could disassemble it and zap the parts with some simple green to see if that helps. I used very warm (microwaved simple green) on some fuel injectors in an ultrasonic bath and

the simple green turned black.  

 

Very interesting on the alternative expansion valve.  It sure would be nice to have one that you can adjust for superheat.

[Dave WM]

no to the ultra sound but I have been looking into getting one. I was cleaning it some more with q tips when I found the needle would come out exposing the hole for cleaning with some paint gun spiral brushes. I used those on it. The needle is actually a rod with a ball on the end. The ball is what you see after removing the brass set screw and spring. There was no change in the flow after more cleaning, so I think I am about as good as its going to get. My current AC setup is working well  so will put this away for now. I need to get back to the transmission swap, been putting that off to get little stuff out of the way.