Atkinsfan

Hi everybody,

I have liked rotaries since 1967 when I toured the Mazda plant. Contrary to instructions, I took pictures of the original Mazda Cosmo (ugly) The engineers still hadn't sorted the apex seal thing out and they were testing literally everything just like Edison and the electric lightbulb filament. The translator said they were working on carburized ox bones at that particular time. I sort of inherited a na 1986 RX7. It got hard to start and a couple of times I had to tow it to get it started and when it did start, it laid down a smoke screen like in a WWI movie clip. A talk with an acquaintence who raced RX7s led to the purchase of a new Atkins engine and I installed it with only one problem that the racer fixed. It was timing related and the engine made a quacking sound on rapid acceleration, not under load. The car ran fine for about two years then the horn died and a new relay fixed it. Brakes, windshield wipers, other consummables were all that it needed over the next 2 years. I was happy. Now I have a vexing problem but first an observation or two:

Observations on oil 1: I worked alongside a petroleum engineer for several years and we had wide ranging discussions on oil - I asked him about 2 strokes and mixing ratios: If an engine manufacturer specified 40:1 would the engine last longer if fueled at 30:1? My thinking was that it would run richer and cooler and maybe require more frequent plug changes but on balance would be rewarded with longer engine life because of lower thermal stress and better lubrication.

His answer - No, such an engine would run leaner, hotter but since the change was marginal, probably not be noticed. Reasoning: The oil in a 2 stroke is a lubricant, not fuel. That's why there's a blue cloud following outboard power boat racers. 99.99% of the lubricating oil will not burn at the low compression ratios in a gasoline engine and if you displace a volume of fuel with something that isn't fuel, the combustion mixture is leaner. Leaner mixtures run hotter. He said the metering devices that increased the volume of oil based on throttle position were the cat's a-- because they took dynamic conditions into account - higher throttle positions = more fuel, more air permitting the engine to use more oil without leaning the mixture in the combustion chamber.

I think there are operating similarities between 2 stroke enginnes and rotaries. I read the archives and got the impression that some people were thinking like I used to -intuitively - that more oil was better.

Observation 2: Japan imports all its oil. In 1967, if I remember correctly, they had only 2 producing oil wells on the Northern islands. That pretty much means that a refiner in some other country produced whatever oil is in the Japanese bottle. Find out which refiner produced it and buy their product without the rebottling markup.

Observation 3: Sequence tests - that's what the letters SD, SJ and so forth are all about. The tests are about sliding a disk down an incline at different temperatures. sliding two pieces of metal against each other at different pressures and lots of other esoteric stuff I no longer remember. The petroleum engineer said that to earn a designation, the oil being tested had to pass all the tests but didn't get extra credit for exceeding them so some oils exceeded the requirements and some only just met them. Not all oils are created equal and right now I'm using Shell Rotella T, a diesel oil. For why, go to an oil discussion board.

Vexing problem: The heater blower motor quit working. I know the motor itself is good. The relay just above the motor clicksbut when I test the voltage, it vaties from 0 when the fan's slidecontrol is off then, when the relay clicks, it varies from 3V to about 7V. There's a power transistor but I think (I COULD BE WRONG) that when the fan motor is on high, the power transistor is bypassed. Anybody out there able to provide any sage advice? Have any experience with this? Any hints/guesses? I'm getting desperate - Oh and by the way, the heater control panel and its attached amp would have been a $600 part but its no longer available.

Icemark

sounds like the blower resistor is bad. But your description is a little vague.

and both the Logicon and blower amp are still available through Mazda and Mazdatrix. I also offer rebuilt ones when I have them in stock.

and if you have problems you probably want to post questions seperate of observations or comments.

Atkinsfan

Thanks Mark for the quick response. The local dealer's parts department told me that the parts I mentioned were no longer available. In future I will separate observations from questions.

The Haynes manual's schematics are not representative of the wiring in the car - they seem more like over-generalizations. They do not show a blower resistor. I have disassembled the air duct/blower system and found the power transistor that was in the schematic - it's a Toshiba 2SD1460, but I can't check it until I desolder a tiny capacitor connecting two terminals. I didn't know there was a resistor for the blower motor. I uncovered a capacitor that was covered with disintegrating foam and checked, it was OK. I also found a chunk of wire that I assuumed was a fusible link. It was enclosed in a white, opaque, plastic tube. It was OK as well. When I mentioned the voltages I should have stated that I measured them at the plug that powers the blower motor with the slide at the far left, the solenoid "off" for the 0 reading then "on" for the other readings, the slide moving left to right farther left for the low then full right at max for the highest reading, still well below 12 volts.

Where will I find the blower resistor?

snowball

if you look in the FAQ's theirs the full factory service manual. give that a try.

Atkinsfan

Thank you Snowball. Back now for a more careful look at the FAQs.

Dmonhunter

http://www.wankel.net/~krwright/cars/rx7/85_manual.html
I think this will hyperlink for you to get to the FSM-- if not, let me know- in email, and will send it to you, maybe save you some time searching faqs
G.L.

Dmonhunter

oops-gave you the 1st gen FSM, sorry, forgot you have an '86
here:
http://www.wankel.net/~krwright/cars/rx7/88_manual.htm
Try that one, i think 88 will be the same

Atkinsfan

Thanks Dmonhunter, You guys are not only helpful but fast. I found the section in the FAQs, located the position of the blower motor resistor but really appreciate the testing algorithm. I'll follow it tomorrow to find out how much it will cost to fix the blower.

Atkinsfan

Thank you everybody,

I have hard copies or the relevant sections of the shop manual, testing algorithm and will now use the information along with my trusty VOM and do the fix. If it turns out to be the logicon, I will install a simple on-off switch to control the blower. Multi speed fans are overrated anyhow. Again, thank you for your help.