My 1990 300zx Twin Turbo build by megaDan

6 minute(s) of a 731 minute read

I'll have more details on this later. Parts for the gage were delivered months ago but as usual summer gets busy and other priorities take over. My plan is to have the gage be hands-free, yet display multiple metrics. Information displayed would be based on driving conditions. Probably a pipe dream, but in my head I can make it work.


This spring was great, took the Z everywhere when it wasn't snowing. Our 4th annual 24h of LeMans pool party was a partial success. The forecast here was pretty grim, forecasting low 70s and rain. I woke up a little after 5am and saw beautiful sunshine! We managed to enjoy a good 5 hours of the race by the pool before the wind picked up and the clouds rolled in. LMP1 was a bore again this year, but we had a great time watching the battle for GTE Pro.

But as soon as summer started work and life got in the way. I think I might have driven it twice in the month of July. June ended with constant chaos at work which led into a much needed vacation during the week of 4th of July.

Her parents have a great view of the mountains and Mother Nature put on a great show for the 4th.

It wasn't quite as hot or humid as I expected, but it was still pretty brutal. The dogs agreed.


I was super disappointed that I didn't get to bring the Mini. It was really tough being stuck in driving paradise with a Nissan Murano. Uuuuuugh. Upon our return I got the Z up on stands again to begin prepping for AC re-activation. I finally found an idler pulley that was serviceable so I pulled the compressor, drained the old oil, and added new stuff. The clutch appears to function and everything seems OK here.

I've been able to avoid this position most of the year so far...

Out with the old, in with the new.


I installed a new dryer that I purchased at least 5 years ago with hopes of getting this done eventually. No drama here.

OEM Parts!


I pulled vacuum on the system for a few hours, and went to add the first can of refrigerant when I ran into a massive roadblock. I couldn't get the system to ingest it. After a bunch of troubleshooting I came to the terrible realization that the R134a adapter fitting I installed did not work. It has a schrader valve inside that is apparently supposed to push on the R12 schrader valve. Or I was supposed to remove the R12 valve....I'm not sure. Either way, the R134a schrader valve would not open regardless of the status of the valve inside the R12 adapter. I disassembled the R134a valve, removed the portion that seemed to be malfunctioning and put it back together and it was immediately clear it had worked. This means that all the vacuum tests I had done previously....were only testing the vacuum of the manifold gages. What a huge disappointment.

Now that I finally had the ability to access the system I pulled vacuum again and couldn't get the system to go below -20mmhg which indicated a massive leak. I rigged up a quick way to apply shop air to the system and heard whistling coming from the condesner. At least I was finally getting somewhere, but quickly lost hope again when I saw that condensers are NLA and what little stock remains goes for $350. I worked on this on and off over the course of two weeks, as I was still traveling for work and Ultimate (7th place @ Men's Masters Nationals!). I removed the condenser with the expectation that I could either A) take it to a radiator repair shop or B) Attempt to repair it myself with some aluminum rod and MAP gas. Sadly neither of these were an option. This project just isn't going well. The only positive so far is that I was able to get the condenser out in about 30 minutes, despite having to remove the mechanical fan and radiator first.

The condenser was pretty well corroded and had a massive hole in it.

A few nights ago I got discouraged and put the car back together minus one condesner so I could at least enjoy the cool summer weather. I removed the dryer also in the hopes that it will still be usable. I've searched ebay, every parts vendor I can think of, and the forums with no luck finding a part-out condenser. Yesterday I finally got a hit while searching all major southern metropolitan areas for either salvage yards or 300ZX part-outs on craigslist. I found a salvage yard that is willing to ship one to me; hopefully I'll have an update next week that doesn't involve cursing as a result of another massive vacuum leak somewhere.

By the time I get this done it will probably be too chilly for AC. At this point I just want it working, as next year I'll have much less time to tinker as we recently found out our first kid is on the way.......