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Anyone have an idea when/ if we need to change the timing belt? I assume we have a belt and not a chain.
Timing belt
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I have an 87 Citroen 2CV that does not have a chain or a belt but a gear on the crank meshing with a larger gear on the cam.
the larger gear is split in two with the two halves spring loaded in opposite directions to compensate for gear teeth wear.No breaking and no maintenance now thats what I call engineering and on a 70 year old design.
DGate
the larger gear is split in two with the two halves spring loaded in opposite directions to compensate for gear teeth wear.No breaking and no maintenance now thats what I call engineering and on a 70 year old design.
DGate
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366 Posts
Good to hear that it is a chain. I wondered why I couldn't find any place in the manual where it mentioned when to replace the belt. On our Prelude, it was at 90,000 and since we are coming to the big 105,000 mile check on the Insight, I thought it would be at that time.
Thanks for the help guys.
Thanks for the help guys.
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1,291 Posts
Properly engineered engines don't have a timing belt or a chain, because they don't have cams.
(Sorry, couldn't resist).
(Sorry, couldn't resist).
[quote Used to have an RX-3 years ago. It was a wonderful car for long-distance trips on interstate highways, but miserable to drive in traffic or on mountain roads.[/quote] I drove a 1981 RX-7 with a 1982 rear end (rear disc brakes, limited slip differential), with an aftermarket, adjustable hiem joint, rear anti-swaybar, from 1988 until 1995, it was anything! but miserable on mountain roads. :evil:
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The problem was not the engine, but the horrid carburetor supplying the A/F mixture.
The problem with the RX-3 and mountain roads, as with city traffic, had nothing to do with the suspension & handling - which if not in the Austin-Healey class, was far superior to the average car of the time. It was the performance of the engine under varying acceleration, particularly at low rpm. Below 3K or so (IIRC) you'd get clouds of smoke coming out the exhaust.
Oil lubrication on the "apex" wipers/seals. They were also a heavy poluteing engine, similar to a two stroke.
They ran extemely hot and the first time they overheated it would warp the rortor.
The HP curve was unlimited, and just kept riseing as the rpm increased.
No torque, but unlimited red line.
Terrible gas mileage comparded to the latest model.
I drove my (1970?) rx3 wagon like a f1 car and it was great. 8)
Willie
They ran extemely hot and the first time they overheated it would warp the rortor.
The HP curve was unlimited, and just kept riseing as the rpm increased.
No torque, but unlimited red line.
Terrible gas mileage comparded to the latest model.
I drove my (1970?) rx3 wagon like a f1 car and it was great. 8)
Willie
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1,291 Posts
A lot of misinformation here...
If there was clouds of smoke coming from the exhaust under 3K, then there was a problem with the engine or carburetor somewhere. A worn engine generally will smoke at high RPMs but be fine at low. If a rotary is smoking at low RPM, it is really worn. An engine that worn would be unbearable at high RPM as the massive white/blue clouds of oil smoke would blind anyone behind. More then likely it was a carburetor problem. The old Nikki carb had a tendency to stick the secondaries a little open, dousing fuel into the engine at low RPM. This not only makes it drink fuel like no tomorrow, but also washes the lubrication film off the chambers and allows oil to bypass the oil control rings. Thus high oil consumption and smoke.
The lack of torque under 3K is relative as well. While the rotary is a high RPM engine, comparing the dyno charts of a modern engine (but NOT the Renesis) shows a very linear torque curve. The older carbureted engines had a seeming lack of torque, until you consider that they are in fact 1.1 or 1.3 litre engines. The simple fact is that if you expect to be able to floor it at low RPMs and get moving it ain't going to happen. Go down a gear like you should.
Mazda's rotary engines use a metering oil pump to supply a small amount of oil to the apex seals for lubrication. This oil is burned as part of the combustion cycle. From the factory, these pumps are adjusted to supply the minimum amount of oil necessary and therefore should not smoke. Sometimes people crank them up, or start premixing 2 stroke oil into their fuel. If the pump is cranked too far or there is too much premix (especially combined with a rich mixture) then there will be smoke.
There certainly is a redline. It's clearly defined on the tach. And there's a loud joybuzzer to let you know you're there. Over revving can and does completely trash engines. Without balancing, clearancing, windowed bearings and oil mods then 8K (9K on later engines, 10K on the Renesis if I remember correctly) is the redline. If you want to go higher, then the engine should be built for it. Otherwise at high RPMs you will start to get eccentric shaft flex which can cause the tips of the rotors to come into contact with the housing, or the rotors can lean over and contact the irons. Both being very bad things.
Does the rotary run hotter then an equivalent sized piston engine? That's a good question and in my opinion the answer is no. The factory thermostat is 84 degrees. Do they produce more heat? Absolutely. It's a high revving engine that fires 3 times per rotor revolution and does not have the benefit of the incoming fuel charge cooling the exhaust area like a piston engine does. Also keep in mind that the only way to cool the rotors is with a set of oil jets that spray the insides of the rotors from the eccentric shaft. Thus the need for an oil cooler which accounts for about 30% of engine cooling. For some idiotic reason Mazda tried a oil to water cooler in the early '80s on the RX-7 which was a disaster. Soon after Mazda went back to a proper oil to air unit. Overheating can be instant death, but unless it is severe, the engine will survive. If the overheating is bad enough then you can warp rotor housings or irons. The result can be coolant leaking into the engine and the need to rebuild (and it's rare to get usable parts from a water pumper if they are left to sit any length of time...).
As for pollution, Mazda was able to pass emissions in the '70s with out cats due to the low NOX emissions of the rotary. They used a bizarre thermal reactor system to deal with the hydrocarbons. Later on they went to cats, and fuel injection cleaned things up a lot. But still, it's a high overlap engine and it does pollute more then it's piston counterpart. The Renesis made major improvements in pollution by virtually eliminating port overlap through moving the exhaust ports to the irons. The Renesis is much cleaner but unfortunately the side ports really limit the amount of power available from the engine.
Yes, gas mileage is terrible.
If there was clouds of smoke coming from the exhaust under 3K, then there was a problem with the engine or carburetor somewhere. A worn engine generally will smoke at high RPMs but be fine at low. If a rotary is smoking at low RPM, it is really worn. An engine that worn would be unbearable at high RPM as the massive white/blue clouds of oil smoke would blind anyone behind. More then likely it was a carburetor problem. The old Nikki carb had a tendency to stick the secondaries a little open, dousing fuel into the engine at low RPM. This not only makes it drink fuel like no tomorrow, but also washes the lubrication film off the chambers and allows oil to bypass the oil control rings. Thus high oil consumption and smoke.
The lack of torque under 3K is relative as well. While the rotary is a high RPM engine, comparing the dyno charts of a modern engine (but NOT the Renesis) shows a very linear torque curve. The older carbureted engines had a seeming lack of torque, until you consider that they are in fact 1.1 or 1.3 litre engines. The simple fact is that if you expect to be able to floor it at low RPMs and get moving it ain't going to happen. Go down a gear like you should.
Mazda's rotary engines use a metering oil pump to supply a small amount of oil to the apex seals for lubrication. This oil is burned as part of the combustion cycle. From the factory, these pumps are adjusted to supply the minimum amount of oil necessary and therefore should not smoke. Sometimes people crank them up, or start premixing 2 stroke oil into their fuel. If the pump is cranked too far or there is too much premix (especially combined with a rich mixture) then there will be smoke.
There certainly is a redline. It's clearly defined on the tach. And there's a loud joybuzzer to let you know you're there.
Over revving can and does completely trash engines. Without balancing, clearancing, windowed bearings and oil mods then 8K (9K on later engines, 10K on the Renesis if I remember correctly) is the redline. If you want to go higher, then the engine should be built for it. Otherwise at high RPMs you will start to get eccentric shaft flex which can cause the tips of the rotors to come into contact with the housing, or the rotors can lean over and contact the irons. Both being very bad things.Does the rotary run hotter then an equivalent sized piston engine? That's a good question and in my opinion the answer is no. The factory thermostat is 84 degrees. Do they produce more heat? Absolutely. It's a high revving engine that fires 3 times per rotor revolution and does not have the benefit of the incoming fuel charge cooling the exhaust area like a piston engine does. Also keep in mind that the only way to cool the rotors is with a set of oil jets that spray the insides of the rotors from the eccentric shaft. Thus the need for an oil cooler which accounts for about 30% of engine cooling. For some idiotic reason Mazda tried a oil to water cooler in the early '80s on the RX-7 which was a disaster. Soon after Mazda went back to a proper oil to air unit. Overheating can be instant death, but unless it is severe, the engine will survive. If the overheating is bad enough then you can warp rotor housings or irons. The result can be coolant leaking into the engine and the need to rebuild (and it's rare to get usable parts from a water pumper if they are left to sit any length of time...).
As for pollution, Mazda was able to pass emissions in the '70s with out cats due to the low NOX emissions of the rotary. They used a bizarre thermal reactor system to deal with the hydrocarbons. Later on they went to cats, and fuel injection cleaned things up a lot. But still, it's a high overlap engine and it does pollute more then it's piston counterpart. The Renesis made major improvements in pollution by virtually eliminating port overlap through moving the exhaust ports to the irons. The Renesis is much cleaner but unfortunately the side ports really limit the amount of power available from the engine.
Yes, gas mileage is terrible.
Won't disagree with any of that - and keep in mind that I'm remembering back to my experience in the late '70s, so it's not like I've got the car handy to check, or practice improved driving techniques But IIRC what I read at the time said a lot of the smoke & low-end performance was due to inadequate seals on the rotor.
I don't remember cruising fuel economy as being all that bad, certainly not in comparison to American cars of the time. (A low standard, I admit.) It was a great car for the job I had, which put me at a job site for a few weeks, then on to the next which might be hundreds of miles away.
But IIRC what I read at the time said a lot of the smoke & low-end performance was due to inadequate seals on the rotor.I don't remember cruising fuel economy as being all that bad, certainly not in comparison to American cars of the time. (A low standard, I admit.) It was a great car for the job I had, which put me at a job site for a few weeks, then on to the next which might be hundreds of miles away.
James the smoke from a rotary has nothing to do with the seals.
The smoke comes from injecting oil into the combustion chamber with fuel to lubricate the rotor as in a two stroke reciprocating engine.
Its burnt and exhausted out the tail pipe as smoke.This is why in my other comment I said they were inherently dirty.
Deteriorating seals cause difficult starting and loss of performance but unlike a conventional recip piston engine with bad rings does not let oil pass from the sump since this is physically impossible.
The sump in a rotary is closed off from the engine workings and is never contaminated with blow by or contact with the combustion process.
Thats why they never need an oil change only topping up as the oil is metered into the intake with the fuel and is consumed.
Speaking of performance remember these were very small engines and like turbines have their own unique characteristics with not much torque low down.
DGate
The smoke comes from injecting oil into the combustion chamber with fuel to lubricate the rotor as in a two stroke reciprocating engine.
Its burnt and exhausted out the tail pipe as smoke.This is why in my other comment I said they were inherently dirty.
Deteriorating seals cause difficult starting and loss of performance but unlike a conventional recip piston engine with bad rings does not let oil pass from the sump since this is physically impossible.
The sump in a rotary is closed off from the engine workings and is never contaminated with blow by or contact with the combustion process.
Thats why they never need an oil change only topping up as the oil is metered into the intake with the fuel and is consumed.
Speaking of performance remember these were very small engines and like turbines have their own unique characteristics with not much torque low down.
DGate
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That's not quite true. You'll get blowby through the side seals which ends up bypassing the oil seals and into the "crankcase" via the center hole in the irons through which the eccentric shaft passes. Just like a piston engine the rotary has a PCV system to vent the vapours. Though Mazda's system is a bit more well designed in that it sucks fresh air deep into the center of the engine and then draws it off from the oil filler neck to really purge the engine. High power turbo engines tend to have a problem with blowby as the stock system cannot keep up when there is no vacuum present in the intake tract.Dgate said:
They most certainly do need an oil change and the schedule very clear in the owners manual like any other vehicle. Especially if the car is turbocharged.
Normal consumption levels on the older mechanical metering oil pump is about 1 quart per 1000 miles. The newer electronic pumps cut that in half but there is a quite a bit of debate as to whether this is a good thing.
Aaron we are both probably correct since I cannot speak for the Mazda but am referring to a different rotary.
The NSU Ro80 I am referring too was the first car to be designed around this new engine developed by the inventor Felix Wankel.I have owned and run for several years two of these and they do not require oil changes due to non contamination from blowby.They do have to be topped up due to the metering system.
NSU tried to make the engine as maintenance free as possible and tested this one feature over 4 years and 3 million miles preceded and accompanied by bench testing to evaluate the road test results before deciding to abandon oil changes.
This was at a time in its history when every other manufacturer was applying for a license from NSU to make this engine.The Ro80 was the flagship definitive rotary car,aerodynamic,front wheel drive,lite wt and German quality.
The killer was this was a small company that was unable to sustain the cost of further development.The fuel crisis hit in the seventies finally killing the rotary off but not before being absorbed by Audi.
Mazda has probably made changes to the design beyond the original concept.
DGate
The NSU Ro80 I am referring too was the first car to be designed around this new engine developed by the inventor Felix Wankel.I have owned and run for several years two of these and they do not require oil changes due to non contamination from blowby.They do have to be topped up due to the metering system.
NSU tried to make the engine as maintenance free as possible and tested this one feature over 4 years and 3 million miles preceded and accompanied by bench testing to evaluate the road test results before deciding to abandon oil changes.
This was at a time in its history when every other manufacturer was applying for a license from NSU to make this engine.The Ro80 was the flagship definitive rotary car,aerodynamic,front wheel drive,lite wt and German quality.
The killer was this was a small company that was unable to sustain the cost of further development.The fuel crisis hit in the seventies finally killing the rotary off but not before being absorbed by Audi.
Mazda has probably made changes to the design beyond the original concept.
DGate
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As much as I would love an Ro80 (almost bought one a few years ago) the early NSU rotary is legendary for its unreliability. From what I've heard, owners of the car would often wave to other owners by holding up a number of fingers representing the amount of engines replaced under warranty.
Not at all saying it's a bad car, but specifically saying oil changes are unnecessary is just plain crazy. The NSU KKM has a side seal and oil seal arrangement almost exactly like Mazda . Blowby may have been minimized since it was a peripheral port design but I'm still shocked by not requiring oil changes.
With any luck in a few years I'll have some time to do a complete restoration on a vehicle (after the DeLorean is done) and an Ro80 is top on the list.
Not at all saying it's a bad car, but specifically saying oil changes are unnecessary is just plain crazy. The NSU KKM has a side seal and oil seal arrangement almost exactly like Mazda . Blowby may have been minimized since it was a peripheral port design but I'm still shocked by not requiring oil changes.
With any luck in a few years I'll have some time to do a complete restoration on a vehicle (after the DeLorean is done) and an Ro80 is top on the list.
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