2nd Generation Specific 1986-1992 Discussion

Experts: Pre-purchase inspection questions

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Old 03-01-2015, 06:23 PM
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Default Experts: Pre-purchase inspection questions

I'm going to purchase a car as soon as I can find one I like, and I've always been interested in rotary engines. Knowing that they're a special breed and require special car and feeding that is essentially just a mystery to me, I've always been shy about it. Today I was checking out an E30 BMW, and the guy mentioned that he used to be really into rotaries. What luck! The next car on my list was an RX7. He agreed to come check it out with me and lend me his expertise (which gave me much more confidence in what I was doing). After checking out the car, he raised some concerns that I certainly wouldn't have known were concerning otherwise.

The car is an 86 RX7 NA, and given the manual window winders and such, I assume it's a base model.

Unfortunately, the seller had driven it a short distance before we got to it, and it was slightly warm. This didn't allow me to see it start cold. When it did start (which took a few turns, but nothing excessive), he had to feather the throttle to keep it going. I searched for this symptom here and on the greater internet, but I must lack the proper vocabulary to find someone who has had a similar issue. It eventually got warm enough to not require feathering of the throttle, and began occasionally backfiring (I think) through the exhaust. The rotary guy I brought with me said this is the nature of the beast, but I seriously met the guy just an hour before. No overt reason to doubt him, it just seems like the sort of thing that would have been engineered out before an engine reaches consumers.

The guy I brought with me was keen to smell the oil and the coolant. Interesting approach. I didn't see any oil in the coolant, but there was some foam in the oil cap. The seller claims he doesn't drive it too much, and it sounds like the oil may never fully get up to temp. I'm operating under the assumption that it's just condensation in the oil from the water not getting cooked out from so many short trips in the cold weather. I don't want to make any false assumptions, so I'm leaving this here just in case it's a red flag. I assume my friend was smelling for gas or exhaust in the coolant and oil. Should rotaries have a certain smell to the oil/coolant that I'm unaware of?

Next, the oil pressure seemed pretty high. My guide pointed this out. It was about 60psi on the factory gauge (fairly cold by my reckoning) at idle, and it increased to 100psi or so at full tilt. After it got a bit of heat in it, we were messing with the climate control panel, and noticed it dropped to 50psi (though maybe as low as 30psi at one point) or so at idle. The AC doesn't work but the compressor is still there and belted, so it could have had something to do with load. My guide suggested that I believe is the oil purge valve could be bad and it's not getting vacuum to the crank case. He believes this is the cause of the slightly higher than expected oil pressure.

My guide suggested I get it into second shortly after leaving a light and just flooring it while paying special attention to any dips or hesitations around 3-4K rpm. It was smooth all the way up. I was focusing on control and not getting too illegally fast, so I don't recall what was said or if I pressed on the subject. Something about a numbered throttle valve. Looking into it online, I'm pretty sure I was testing the high rpm throttle bodies (or whatever they are) that open up to let it breathe better at higher RPM. I'm not sure if I should or should not have felt a completely smooth increase in power.

One last major thing was a small rocker switch installed by a previous owner that I'm told operates the fuel pump. He assures me this is a common modification on RX7s, and that he was told they did it on all sorts of cars (though I've never seen or heard of someone doing that). Does that ring any bells? Is this common? Why would someone do that?

There were electrical issues with the wiper switch (looked into, feeling fine with getting that sorted), AC not working (I don't own any other cars with AC, and might just remove it from this one), and the diagnostic stuff doesn't work. Maybe some other things, but nothing I'm super worked up over. There were paint chips here and there that had resulted in light rust, and the passenger side front fender had a good amount of full blown rust behind the wheel, though it seemed isolated to the fender itself.

The transmission felt great, there was a good amount of power, it has a recent emissions test report that shows it passing with flying colors... I think it's a pretty good car. Asking price might be a touch on the high side, but hopefully he's a little flexible there should I not have uncovered anything too dramatic.
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