Restoring a Vintage Sun Engine Analyzer to Diagnose Old Cars

Gearheads love to complain about how modern computerized cars are impossible to work on. But personally, I like that modern cars can often tell us exactly what is wrong with them. In the past, getting any actual data meant using a big, expensive analysis machine. For months now, YouTuber Wrenches & Whitewalls has been working on restoring a vintage Sun Engine Analyzer like that and he may have finally finished the job.

Sun Electric Corporation was a major player in this industry for several decades. During that time, they sold a multitude of different engine analyzers and other kinds of automotive diagnostic equipment. This particular unit was made in the 1970s and would have been on the high-end of the lineup. It has a built-in oscilloscope for analyzing ignition events, plus gauges for everything from engine RPM to vacuum pressure.

Wrenches & Whitewalls likes working on old cars and machines, so he purchased this unit as both a project and a tool to use for those jobs.

When he got it, the analyzer wasn’t working at all. While he had high hopes for it, he was aware that it could just be scrap. It came from a Ford dealership, where it was in service for decades. But it was also in storage for decades after that.

Most of the restoration work went into simply getting it powered up and doing something. Some functions — particularly the mechanical ones, like the vacuum gauge — were working. Others either weren’t working at all or were acting unpredictably. Those were the electronically controlled gauges, which led Wrenches & Whitewalls to months of circuit board repair. He spent a great deal of time replacing components like resistors and transistors, which were well past their service life and had failed.

But the oscilloscope proved to be the biggest headache. Several videos focus on that alone, as it was very troublesome.

About a month ago, Wrenches & Whitewalls reached a point where he was seeing a signal on the oscilloscope. However, the display was flickering and he was becoming frustrated trying to hunt down the cause. In his most recent video, he revealed his revelation: the flickering stops at higher engine RPMs. After finding some diagnostic literature, he concluded that the flickering is just a quirk of the system at idle speeds.

Closed and shut case, right? The Sun Engine Analyzer is working and is ready for service.

Well, not so fast. Commenters who have experience with this analyzer have pointed out that it should not flicker, even at low engine speed. So, it sounds like there may still be a gremlin in there somewhere and I have a feeling Wrenches & Whitewalls will have at least one more video on the subject.

Be sure to subscribe to the Wrenches & Whitewalls YouTube channel to see what happens next in the saga.