Snake oil and high rates of rotation?
10-20-02, 12:06 PM
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Snake oil and high rates of rotation?
Since the rotary is such an obscure engine design there seems to be alot of misinformation and rumours spread regarding how to maintain it and treat it right. Of all of these, the two that seem to be the most perpetuated and misinterpreted is the ATF treatment and the constant redlining that a rotary "supposedly" needs.
ATF is a thick liquid designed to smooth shifts and transfer torque in an automatic transmission. This fluid lacks any carbon-dissolving properties (how does carbon dissolve anyways?) and seems to be screwing more engines up than it fixes them. While I did use ATF as a last-ditch effort on my TII with a blown engine, with a bit of common sense you realize that the engine takes "oil" and the transmission runs best with "transmission fluid". Nowhere in the Racing Beat or Mazdatrix catalogs do they endorse the use of ATF as an engine conditioner NOR as a remedy for a stuck/broken apex seal. I remember reading about people using the ATF "trick" back in the 70's and I suppose it's virtues are still being spread at the backyard BBQ and rotary gatherings, because everytime someone has an engine compression problem, someone suggests ATF. Now, some people even argue that the ATF treatment should be done on a semi-regular basis. I don't have any specific numbers, but I'm willing to bet that the people who use ATF regularly are the ones who complain about losing a coolant seal without overheating or start burning tons of oil at high RPM. If you're going to stuff some liquid in your engine other than the standard coolant or motor oil, then use something that's going to burn easily and not smell like a bunch of pine trees.
Another statement that gets tossed around quite a bit is the whole bit about how the rotary engine runs best if you red-line it often and with enthusiasm. Now, I know that a rotary LOVES to rev, but is it good for it? Spinning pieces of metal at high speeds creates quite a bit of stress. Not only is it stressful on the apex seals, side seals, springs and E-Shaft (not that I've ever heard of an E-shaft failing), but it's hell on your synchros and transmission, especially if you release the clutch with much enthusiasm. How can all of this be good for an engine? I get the idea that it's not, but since people are so interested in a free fix for their car's problems, then they latch onto this idea as another gimmicky solution that really doesn't fix anything.
If anyone has any first hand experience with these two topics, say you ATF"d your TII engine that chowed its apex seals and after you started it up, it had perfect compression, then go ahead and give the jury a testimonial. However, if you were redlining every day on a non-turbo engine and it threw up at 50,000 miles, then give us a rant as well.
I'd also like the rotary gurus on here (RETed, Scathcart, etc.) to chime in. I never hear these guys offer their opinion on these topics and I certainly would like to.
ATF is a thick liquid designed to smooth shifts and transfer torque in an automatic transmission. This fluid lacks any carbon-dissolving properties (how does carbon dissolve anyways?) and seems to be screwing more engines up than it fixes them. While I did use ATF as a last-ditch effort on my TII with a blown engine, with a bit of common sense you realize that the engine takes "oil" and the transmission runs best with "transmission fluid". Nowhere in the Racing Beat or Mazdatrix catalogs do they endorse the use of ATF as an engine conditioner NOR as a remedy for a stuck/broken apex seal. I remember reading about people using the ATF "trick" back in the 70's and I suppose it's virtues are still being spread at the backyard BBQ and rotary gatherings, because everytime someone has an engine compression problem, someone suggests ATF. Now, some people even argue that the ATF treatment should be done on a semi-regular basis. I don't have any specific numbers, but I'm willing to bet that the people who use ATF regularly are the ones who complain about losing a coolant seal without overheating or start burning tons of oil at high RPM. If you're going to stuff some liquid in your engine other than the standard coolant or motor oil, then use something that's going to burn easily and not smell like a bunch of pine trees.
Another statement that gets tossed around quite a bit is the whole bit about how the rotary engine runs best if you red-line it often and with enthusiasm. Now, I know that a rotary LOVES to rev, but is it good for it? Spinning pieces of metal at high speeds creates quite a bit of stress. Not only is it stressful on the apex seals, side seals, springs and E-Shaft (not that I've ever heard of an E-shaft failing), but it's hell on your synchros and transmission, especially if you release the clutch with much enthusiasm. How can all of this be good for an engine? I get the idea that it's not, but since people are so interested in a free fix for their car's problems, then they latch onto this idea as another gimmicky solution that really doesn't fix anything.
If anyone has any first hand experience with these two topics, say you ATF"d your TII engine that chowed its apex seals and after you started it up, it had perfect compression, then go ahead and give the jury a testimonial. However, if you were redlining every day on a non-turbo engine and it threw up at 50,000 miles, then give us a rant as well.
I'd also like the rotary gurus on here (RETed, Scathcart, etc.) to chime in. I never hear these guys offer their opinion on these topics and I certainly would like to.
10-20-02, 01:14 PM
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On the other hand, ATF isn't rattlesnake venom nor any other particularly toxic substance. It's only a kind of hydraulic fluid designed to transfer forces around in the maze of orifices in an automatic trant. It's a simple, light (not thick) pertochemical derivative, thats somewhere between the gasoline and the motor-oil that the RX7 injests by design. Certainly there is a different additive package that's designed for the tranny application, but inside the auto trannys are a large number of rubber "O-ring" seals, firbous shaft seals, hydraulic valve seals. I doubt that the RX7 contains "O-rings" or rotor seals made of a material much different, or particularly more delicate, than what is seen in the basic automatic tranny.
The upshot of this is that, while the benefit of ATF'ing a RX7 engine is arguable, the probability of untoward consequences are even less likely
......... unless the rotary can hydrolock, like a recip. engine can; and then, I'd accept some argument that post-ATF'ing damage to the stressed elements was a possibility.
The upshot of this is that, while the benefit of ATF'ing a RX7 engine is arguable, the probability of untoward consequences are even less likely
......... unless the rotary can hydrolock, like a recip. engine can; and then, I'd accept some argument that post-ATF'ing damage to the stressed elements was a possibility.
10-20-02, 01:18 PM
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The theory behind 'atf', at least in piston engines, is that it has a higher detergent content compared to motor oil. If you ran the motor with 1qt of atf to replace 1qt of oil, got it nice and hot, for 15 minutes or so (no driving), it would loosen up carbon stuck rings and lifters. I don't think it dissolved carbon, just made it softer. The rotational and reciprocating forces would do the work.
The 'instant' tune up liquids and such were usually variations of high detergent oil.
I do know that if you have a high mileage aircooled VW, it is recommended that you use a 'straight' oil (SAE-30) and not to use oil with high detergent content. The danger is that if you have carbon oil muck built up in the motor, the detergent would loosen it and it could travel up to the oil cooler and clog it. Bye-bye motor.
In that respect, if you have a bit of carbon stuck on a seal (preventing chamber sealing) or if the motor has sat for a while and an apex seal is stuck 'compressed, I can see where atf might be of some help.
A 'cure all'? I doubt it. Regularly? Not me.
My question (if I may add one) is, has anyone that had success with the ATF technique, recorded compression readings before and after?
In other words, does a car with 0 or low compression an all faces of a rotor respond to the treatment or does a car with low compression on two adjacent faces(sharing an apex seal) respond to it?
Which cars have responded? The one that died while driving or the one that just didn't start one day?
As for 'redlining', it may be a similiar thing, high rpm loosens and blows carbon out. (My car will start to run rough after awhile and if I get it hot and wind it out a few times (6500-7000 rpm) it will smooth out and idle better) Just make sure your oil metering pump is working correcly. My motor was replaced 20k ago by the previous owner (a shop did the work) and the omp rod was not adjusted right. It didn't engage until 1500+rpm and at 2000rpm it put out less than half the specified oil. Now I wonder about the llife of my motor. Maybe that is why rebuilt motors have a supposed reduced lifespan? Also, if the oil injectors are clogged (oil sitting in them on top of a hot motor can/will leave deposits) it doesn't matter what the pump does.
The 'instant' tune up liquids and such were usually variations of high detergent oil.
I do know that if you have a high mileage aircooled VW, it is recommended that you use a 'straight' oil (SAE-30) and not to use oil with high detergent content. The danger is that if you have carbon oil muck built up in the motor, the detergent would loosen it and it could travel up to the oil cooler and clog it. Bye-bye motor.
In that respect, if you have a bit of carbon stuck on a seal (preventing chamber sealing) or if the motor has sat for a while and an apex seal is stuck 'compressed, I can see where atf might be of some help.
A 'cure all'? I doubt it. Regularly? Not me.
My question (if I may add one) is, has anyone that had success with the ATF technique, recorded compression readings before and after?
In other words, does a car with 0 or low compression an all faces of a rotor respond to the treatment or does a car with low compression on two adjacent faces(sharing an apex seal) respond to it?
Which cars have responded? The one that died while driving or the one that just didn't start one day?
As for 'redlining', it may be a similiar thing, high rpm loosens and blows carbon out. (My car will start to run rough after awhile and if I get it hot and wind it out a few times (6500-7000 rpm) it will smooth out and idle better) Just make sure your oil metering pump is working correcly. My motor was replaced 20k ago by the previous owner (a shop did the work) and the omp rod was not adjusted right. It didn't engage until 1500+rpm and at 2000rpm it put out less than half the specified oil. Now I wonder about the llife of my motor. Maybe that is why rebuilt motors have a supposed reduced lifespan? Also, if the oil injectors are clogged (oil sitting in them on top of a hot motor can/will leave deposits) it doesn't matter what the pump does.
Last edited by opelbits; 10-20-02 at 01:20 PM.
10-20-02, 06:04 PM
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Opinions are like........
There is no fix for a broken apex seal.
A stuck apex seal is caused by what???
I think that everyone should prevent stuck apex seals. Changing the oil frequently and performing regular tuneups should prevent stuck apex seals.
I don't constantly bounce off the rev limiter. But, it happens occasionally. At 100k miles, I am happy with the power/performance of the original engine. Plus the rotary doesn't have the stroke/rod/piston side to side loads that boingers have. The rotors spin at 1/3 engine rpm and everything was designed to operate at higher rpms. Oil pressure is important at higher rpms. So is engine balance. As long as you have consistent oil pressure, high rpm shouldn't be an issue.
ATF has strong detergents to prevent tranny varnish buildup. Anyone who every rebuilt a tranny knows that varnish is a PITA to remove. In my personal tests, MMO loosened up carbon quicker than ATF and burns quicker/easier. Anything that could help remove carbon on a poorly maintained/tuned engine could help. This doesn't mean that it will help. It depends on what the original engine problem is. Also, ATF could soak into certain seals. It conditions seals well and this could help oil control and compression in certain engines.
The problem with ATF is that people want to believe(wish) that it is a substitute for a rebuild. In low/no compression instances, rebuild is the only solution.
A stuck apex seal is caused by what???
I think that everyone should prevent stuck apex seals. Changing the oil frequently and performing regular tuneups should prevent stuck apex seals.
I don't constantly bounce off the rev limiter. But, it happens occasionally. At 100k miles, I am happy with the power/performance of the original engine. Plus the rotary doesn't have the stroke/rod/piston side to side loads that boingers have. The rotors spin at 1/3 engine rpm and everything was designed to operate at higher rpms. Oil pressure is important at higher rpms. So is engine balance. As long as you have consistent oil pressure, high rpm shouldn't be an issue.
ATF has strong detergents to prevent tranny varnish buildup. Anyone who every rebuilt a tranny knows that varnish is a PITA to remove. In my personal tests, MMO loosened up carbon quicker than ATF and burns quicker/easier. Anything that could help remove carbon on a poorly maintained/tuned engine could help. This doesn't mean that it will help. It depends on what the original engine problem is. Also, ATF could soak into certain seals. It conditions seals well and this could help oil control and compression in certain engines.
The problem with ATF is that people want to believe(wish) that it is a substitute for a rebuild. In low/no compression instances, rebuild is the only solution.
10-20-02, 07:59 PM
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There is a spring behind the seal. If the seal is compressed for an extended period of time it can stick (if there is sufficient carbon buildup from too much oil or gas, stop and go driving, lots of idling). Think of a hydraulic lifter that sticks when it is compressed. Very similiar thing.
The only two things I can see that would cause this stuff (aside from detonation damage or some other similiar thing) would be running rich (carbon/fuel additive buildup) or faulty omp/lines/injectors (not enough lubricating/sealing oil getting into chambers or too much).
Is there anyone with more rotary experience to confirm/deny any of this?
The only two things I can see that would cause this stuff (aside from detonation damage or some other similiar thing) would be running rich (carbon/fuel additive buildup) or faulty omp/lines/injectors (not enough lubricating/sealing oil getting into chambers or too much).
Is there anyone with more rotary experience to confirm/deny any of this?
10-22-02, 03:47 PM
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Originally posted by deadRX7Conv
The problem with ATF is that people want to believe(wish) that it is a substitute for a rebuild. In low/no compression instances, rebuild is the only solution.
The problem with ATF is that people want to believe(wish) that it is a substitute for a rebuild. In low/no compression instances, rebuild is the only solution.
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10-25-02, 04:57 PM
#8
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I'm with opelbits and deadRX7Conv with the high "detergent" additives in ATF...
As for spinning it higher, keep in mind that the ratio of eccentric shaft rotation (i.e. RPMs) is 3:1 versus the rotor, so the rotor (and parts) are spinning at 1/3rd the speed.  Now, I think the advice of running up to redline is more to keep carbon build-up minimized, not so much as overstressing the engine parts.  The rotational path of the rotary engine is a lot easier on parts versus a piston engine which has to stop and change direction!
-Ted
As for spinning it higher, keep in mind that the ratio of eccentric shaft rotation (i.e. RPMs) is 3:1 versus the rotor, so the rotor (and parts) are spinning at 1/3rd the speed.  Now, I think the advice of running up to redline is more to keep carbon build-up minimized, not so much as overstressing the engine parts.  The rotational path of the rotary engine is a lot easier on parts versus a piston engine which has to stop and change direction!
-Ted
10-25-02, 05:39 PM
#9
The Test: my 1988 AE.
The Background: Car had died at a stoplight. P.O. restarted and drove home (about one mile.) car was running poorly and refused to start the next day. Car sat for 1 year. I buy the car in june or whatever 2002. Car had sat since mar. 2001 Car refuses to start, no matter how long its cranked for. Compression: Front: 80/80/85 Rear: 0/0/0
The test:
I pour some ATF in, wait 10 hours (I put it in at night and just couldn't wait any longer in the morning), try to start. Car fires right away, runs fair. I take it for a test drive. Drives ok. Not alot of power. Makes boost in 4th, good for a top speed of about 120km/h.
I take it home, and check the compression later the next day.
Front: 100/100/110 Rear: 0/0/~60
etc: I drove the car about 40km, and went through 1/3 tank of gas. Ouch.
The Background: Car had died at a stoplight. P.O. restarted and drove home (about one mile.) car was running poorly and refused to start the next day. Car sat for 1 year. I buy the car in june or whatever 2002. Car had sat since mar. 2001 Car refuses to start, no matter how long its cranked for. Compression: Front: 80/80/85 Rear: 0/0/0
The test:
I pour some ATF in, wait 10 hours (I put it in at night and just couldn't wait any longer in the morning
), try to start. Car fires right away, runs fair. I take it for a test drive. Drives ok. Not alot of power. Makes boost in 4th, good for a top speed of about 120km/h. I take it home, and check the compression later the next day.
Front: 100/100/110 Rear: 0/0/~60
etc: I drove the car about 40km, and went through 1/3 tank of gas. Ouch.
10-26-02, 02:26 AM
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Yeah, running it up to high rpm burns carbon off, i can smell it every time i go above 4k, ever driven an rx7 that someone babyed and never shifted above 3k? bad. And the atf thing is just a fix for motors that have an apex seal stuck from carbon either from sitting, or dirty oil or what not. Kerosene works well for cleaning carbon when the motor still runs, somethign that is thicker and doesnt evaporate as fast is better for motors that wont start, like atf or mmo. there is no solution for a broken apex seal, but atf can help a stuck seal
10-27-02, 08:56 PM
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Originally posted by drago86
Yeah, running it up to high rpm burns carbon off, i can smell it every time i go above 4k
Yeah, running it up to high rpm burns carbon off, i can smell it every time i go above 4k
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