TRZ750

Just wrote this for another thread and thought it would make a good post for others:

I started with Mazda Rotaries in 1973. There was a big problem then as the "O" ring between the housings, like a head gasket, would burn through in ~ 30K miles and 3 years for the commuters. It was not a problem for the high mileage guys as the "O" ring was only burned during the warm up period when the aluminun housings were not up to temp. Also any cooling system problem caused overheating and "O" ring damage. In 1974 Mazda started using a special coated ring, larger better designed radiator, water pump, and hoses that eliminated this problem. JD Powers made a big deal about the Rxs failing in 30K back in 1973. Mazda fought this report saying the numbers were wrong, but it was accurate. Then in 1974 Mazda replaced MANY engines for free to satisfy the customers.

Then in 1974 the energy crises hit as Mazda introduced the RX4, Cosmo, and REPU, so expected high sales. Instead the poor mileage (EPA 10~12 guys) caused poor sales and many cars sat at port storage yards near ocean salt water. This caused corrosion to the steel housings and resulting early wear of the internal oil seals. This was amplified by a oil dip stick that was too long and caused many owners to run the oil too low with resulting rotor overheat - rotor expansion and sever rubbing on the steel housings further increasing oil usage until the engine locked up from lack of oil. The funny thing is that the rotors need little cooling around town, but did need it on the highway. So it was common to see a Mazda on the side of a highway with a locked up engine.

I did have a unusual problem with my REPU once. I had been at Lake Havasu with my boat (20' ski boat). Had been camping out so had a lot of stuff loaded in both the truck and boat, so real heavy. I had done this a number of times so had no worries. But on the way back I got stuck in a strong head wind. So strong that I had to run at full throttle on the down hills let along the up hills. Did over 100 miles at full throttle in mostly 3rd gear and 6000 to 7000 rpm. Well no problem on the trip, but after that the engine became hard starting. Since it ran OK once started I ignored it for a while. Three months later I decided to overhaul the engine and found the only thing wrong was the apex seal springs had lost their tension! All else looked good, so just put in new springs and put it back together. The long hard pull must have overheated the springs - softening them.

Another issue you new RX8 people should know about is that the coolant in the rotary needs to be anti-freeze even in Florida! The reason is the steel and aluminum housings are different material and there can be sever corrosion if plan water is used. Any old time Mazda guy can tell you about housings with coolant leaks through holes into a spark plug hole or exhaust port!

All these problems were cured by the time the RX7 was released with improved parts, low oil sensors, low water sensors, etc. As long as the owner keep the engine full of oil and water the engine will easily last a long time. There is no timing belt to replace. The Carb on older engines and EFI on newer engines are not that much different from other cars, so should have the same reliability. Any abuse or exotic systems like nitros or high boost turbos can also hurt the engine, but normal stuff will not be a problem.

Overport

thanks dude.

that serves helpful.

truemagellen

nice you want to make a documentary for us?

RenoIV

Good info

No More Oldsmobiles

Thanks, TRZ750. Very interesting and informative post.

NomisR

Nice writeup, some of the stuff you don't get to see on the Rotary history sites.

Labop

good stuff. thanks.

r2s2

I'm old enough that I'd forgotten much of the history. Well done, thanks.

Battousai

I love these little historical gems, thanks a lot for the write up.

EDIT: On the historical note; maybe many of you know this already, but I found many old Mazda TV commercials on the mazda.ca site's multimedia/ video section.

Pretty cool watching those olds adds, despite how cheesy most were :D

Rotario

Thanks for that, TRZ750. Brings back memories:

My first car was a '72 RX2 that I bought from my Dad in 1974. It was way too much fun with the high revs and the power it had, compared to other cars back then. Its first motor blew at 25k miles, before I was even driving (so Dad couldn't blame it on me, thank goodness). Back then, the warranty was 12 months or 12k miles, so Dad had to pay for the rebuild, and it was expensive. I bought it with 35k miles on it, and the second motor went at 60k miles. Sold it to a guy that rebuilt rotaries on the side (at a substantial loss). In '78 or '79 (can't remember) there was a class-action lawsuit on Mazda for the engine problems, and we (me and my Dad) were sent a check for the initial cost of the car, less what we sold it for, plus any money that had been spent out-of-pocket to repair it. Didn't make up for the hassle and inconvenience, but at least it put things right financially. So why am I driving one now? 2 things: one, the problems have been resolved, and two (and more importaantly), I *love* the rotary engine!

Bill

Swagman

This is bringing back a lot of memories. My first drive in a rotary was an NSU Prinz. The car was a real POS, but the engine was fascinating. My first Mazda rotary was an RX-3 which I "nursed" for three years, even took a really memorable 6 week road trip to Costa Rica and back in this car. It never missed a beat, had over 50k on the odometer, and then my girlfriend at the time drove it home one night with a leaking radiator hose - you know the rest. I've owned 6 rotaries before my 8 and am still fascinated with this little engine. I used to plan my life around IMSA's endurance races just to watch the 7's kick ***.

m477

Well, I guess they really got it right in 1979 then, judging by all the 1st gen people on the rx7 forum with 200k+ on their motors.

msrecant

I had a 1972 RX-2 that I bought new. Ran it until I sold it at 90,000+ miles. At about 70,000 I did have an "O" ring fail. With one part of the housing being steel and the adjacent part being aluminum, when the engine heated up the two parts expanded at different rates which tore the "O" ring apart over time (duh?). In my case, the failure resulted in coolent getting into one rotor chamber. Talk about "smoking" when you started the car, it was like a diesel until all the water was blown out. The dealer installed a factory rebuilt short-block for about $400 including parts and labor , which was a sweetheart deal, even then.

One thing not mentioned in the history was the backfire you could get from the early Mazda rotary engines. It used a thermal reactor for polution control and, if anything was out of whack, fuel vapor would momentarily build up and detonate in the most amazing noise you ever heard.

Also, even though Mazda advertised the 1972 RX-2 as going "hummmmm", they came standard with piston A/C compressors (double duh?) that produced substantial vibration when you had the A/C running. Living in Florida at the time, I could hardly avoid using it.